Tbi Fuel Pressure Regulator Adjustment

Flooding the engine. a flooded carburetor can cause a fire and/or explosion resulting in property damage, serious injury, and/or death. When the injectors and fuel pump are upgraded the stock fuel pressure regulator may not be enough to suit the required pressures for the new setup. in TBI (throttle body injection) systems. Downstream from the fuel injector is a back-pressure regulator which maintains pressure (usually 30-45 psi) all the way back through the fuel rail to the fuel pump. its about power. We found a set of 80 lb/hr injectors on ebay for $60 and used a 15 psi pressure regulator from a junk 350 tbi. Name 56503 High Flow Fuel Pressure Regulator. To avoid interruption from contaminated fuel, a series of fue pump. I have a 95 silverado tbi 5. Swap out the jeep pump and use a stock chevy pump. This is partially due to PCV flow, but can also be an indication of a leaking fuel pressure regulator (arrow). You can replace a fuel pressure regulator with a few common tools at home in most vehicle models, those with systems with Throttle Body Injection (TBI) or newer ones with Electronic Fuel Injection (EFI) systems. The reason I say across the injectors is because it uses a pressure regulator to maintain 40psi pressure difference between the fuel pressure in the fuel rail and the air pressure at the injector tip. Holley Fuel Pressure Regulator Won't Adjust The GENSSI Fuel Pressure Regulator will ensure stable pressures are supplied with the Holley 12-803 Fuel Pump Fuel Pressure Regulator by Genssi for your more common platforms, which won't require you to do any cutting and fitting. For example if your pump flows at 50 gph it should be able to support a 500 hp engine (50 x 10 = 500). The throttle body fuel injection system, or TBI as referred to by GM or CFI by Ford, works using a single or pair of injectors. Got a chevy k2500 with a 5. The Sniper uses four 100-lb/hr injectors and will feed up to a 650hp naturally aspirated engine. I did rebuild the throttle bodies at the time of the install and modified the fuel pressure regulator so it was adjustable while the car was running as per the tech article on the DCS website. 5 are multi port 90 is tbi. I sorta think you should give strong consideration to MPFI, but the TBI will work for you I think, as long as the combo is pretty mild. 85-92 Camaro/Firebird 305/350 TPI BBK Adjustable Fuel Pressure Regulator Kit, includes manifold runner gaskets. Excess fuel is returned to the fuel tank through the fuel return line. I'm using the stock internal regulator in the TBI unit. Skip to content. Fuel Injection Systems Speedmaster™ line of EFI systems is all you need when deciding to upgrade your engine to modern electronic fuel injection. Hook it up to fuel lines and turn on key and watch pressure, you get 2 seconds. Attach the fuel pressure gauge to the Schrader valve on the fuel rail. When I turn the ign on with the fuel pump running, the pressure goes way too high. Connect the fuel line to TBI as per typical carburettor. If you calculate your fuel pressure needs per injector size for estimated HP of engine you should know pressure needed. Neutral switch adjustment. Any unused fuel is bled off by the regulator and returns to the fuel tank via a return line. All we have to do is install the fuel pressure gauge in between the pressure regulator outlet and the nitrous jet. If not, they can be purchased under GM P/N 17111462. if the tbi ecu could sense boost, it would automatically adjust the air/fuel ratio, but thats out of the ecu's ability the good thing about a tbi is that they are ther most upgradeable fuel system offered on a stock 4. It is machined out of billet aluminum which ensures extreme durability. Caution: Fuel will. At full power the engine would quickly starve of fuel. There is an adjustment screw inside which is held in place with a large spot of solder. That leaves one fitting to run through a fuel filter, adjustable fuel pressure regulator (available at any major parts store) and then into the carb. Put a new fuel pump in it & brought it up to 16psi. The reason is there are 2 types of torx screws. What is the fuel pressure? Should be 9 to 13 lbs for the injectors. JET TBI/TPI Adjustable Fuel Pressure Regulators. The same principle of operation applies. You can measure your fuel pressure off the outlet tee from the regulator at the fitting supplied. on how well the fuel tables are feeding the engine. They are built to OEM specifications and offer a precise flow and factory fit. What you are attempting to do is set the maximum fuel pressure. ADJUSTMENT To increase the fuel pressure, turn the adjustment screw counter-clockwise. Min voltage is 10v. This fuel pressure regulator can adjust the fuel pressure into the injector based on the change in intake manifold vacuum and make the difference between fuel pressure and intake manifold pressure remain constant. The TBI Fuel Pressure regulator is a common problem. It's a very common problem on many Chevy, Buick, Pontiac, and Oldsmobile 3. 2 liter TBI engines also did not produce any useful information that we could find. So after having a fuel pump fail due to paint chips in the pump, on my 2005 volvo 5. Fuel Pump, Filter, Regulator and Line A higher output pressure fuel pump is necessary to provide the injection pressure necessary for proper operation. Plus, you shouldn't be playing with any screw in TBI. With the 80lb BBC injectors and a walbro 255 fuel pump. I am trying to adjust my holley red pump down to 5 lbs using a Holley adjustable fuel pressure regulator. If the fuel pressure is below that spec, I just don't know how to determine what it causing the low pressure. In this video I show you the simple steps to adjusting your (FPR) fuel pressure using an adjustable one. Normal failure for a pressure regulator is loss of pressure, not high pressure. Adjustable Fuel Pressure Regulator for TBI equipped F-bodies So far if you've been reading the ultimate TBI series you will have noticed that the TBI unit you have been dealing with is really quite simple and user freindly. If it is reading over about 12 psi then the regulator has at some point been changed from the factory setting. GM TBI 220 & TBI 300 ADJUSTABLE FUEL PRESSURE REGULATOR GM TBI 220 & TBI 300 ADJUSTABLE FUEL PRESSURE REGULATOR adjustment does give the opportunity to change open-loop fuel flow and trim the part-throttle mixture somewhat if necessary. Things I have done: Checked for injector operation. Remove spring and diaphragm assembly (22,23,24) NOTE: Whenever pressure regulator cover is removed, the diaphragm must be replaced to prevent. I'm running an inline TBI fuel pump made for this motor. Earlier you had mentioned cavitation, is it possible to have cavitation in the command center?. A variable fuel pressure regulator for use with an internal combustion engine combines with a fuel pump that discharges fuel at a constant pressure and a carburetor with a fuel controlling needle valve to assure that excessive fuel is not delivered to the carburetor and burned by the engine. Turn regulator on top of Fuel Injector Cleaner to full OPEN position (counterclockwise). The fuel pressure for the 502-6 should be 11 psi. Fuel Pump, Filter, Regulator and Line A higher output pressure fuel pump is necessary to provide the injection pressure necessary for proper operation. ACDelco 217-389 17112907 TBI Fuel Pressure Regulator Cover GM 220 Throttle Body. regulator vacuum line disconnected. For those who have early TBI, here's something. A cell value of 128 is neutral , no fuel is added or subtracted. 7L, 1982-1984 Corvette Crossfire Front and Rear. Open shut-off valve to full OPEN position (counterclockwise). The fuel injection system does not digitally control fuel pressure. This pump is located within the fuel tank itself (which can be a bugger if you have to replace it). The PWM fuel pump is engineered to operate without an external fuel pressure regulator. Preset from Howell at Approx. I don't want to push the pressure past maximum, just want to be sure it is at at least the minimum to try and find if there is a pressure problem. To regulate the fuel pressure, the ECU simply adjusts the pump speed or fuel injector rate. Pressure regulator has a spring chamber that is vented to same pressure as tip of injector. from it tells the computer how to adjust the air/fuel. Connect the Fuel Injector Cleaner to the inlet of the fuel rail. Replacement brand parts are the most affordable solution for all of your replacement needs! All Replacement brand items are backed by a 1-year, unlimited-mileage warranty. A fuel pressure regulator is a device that is used to control the upper limit of the fuel pressure. Need Howell TBI help: Running fuel rich. 3L V6 > Fuel & Air > Fuel Injection Pressure Regulator. Adjust your fuel pressure for maximum power. Remove the fuel lines from the TBI. Attach the fuel pressure gauge to the Schrader valve on the fuel rail. A pressure regulator in the TBI keeps fuel available to the injectors at a constant pressure between 62 and 90 kPa (9 and 13 psi). This will keep chunks of charcoal from the canister out of your float bowl. Engine stalls when you come to a stop, after the engine warms up. There are some aftermarket TBI fuel pressure regulators available where you can tweak the fuel pressure to the injectors and thus the flow via an adjustment mechanism in the regulator spring. Also essentila is a good fuel filter. This Tbi Adjustable Regulator is needed for stock and modified GM tbi engines. Use a fuel pressure gauge to verify that the fuel pressure is 12 psi for 502-4, 502-5, & 502-7. Taking a page from GM when they increased the fuel pressure on the late model 454 TBI from 12psi to 28psi and used a smaller (more common/cheaper) injector that provided better atomization of fuel, we can do the same with ours. One of the mods was putting in a new jet fuel pressure regulator, so I can adjust the pressure if I need to. The built in regulator will fight to maintain this. If the pressure is low it could be the pump, the hose between the pump and the sending unit, or the regulator. Searching trouble shooting guides, we did not find anything indicating spark plug-fouling problems could be related to the fuel pressure regulator. Full Answer. Because differential pressure between injector nozzle and spring chamber is same, only the length of time that injector is energized controls volume of fuel injected. When the fuel line is hooked to the carbs I can turn the adjuster all the way out and it only get down to 6 lbs. Normal failure for a pressure regulator is loss of pressure, not high pressure. After the second visit, they found that the Holley regulator is inconsistent at holding fuel pressure. 0L MPI, 350 Mag MPI & MX 6. Air Fuel Control The Stoichiometric mixture of 14. Fuel Pressure does reach the TBI But the injectors won't release any fuel. If those base settings are correct and it still has the issue then I would be thinking MAP sensor or fuel pressure regulator. When you installed the new 85+ fuel pump it had the power to suppy all the pressure the regulator requested. Re: Little nitrous fuel pressure question WOW do I see it different than you guys, you want to use a flow jet on the fuel side and bypassing fuel not dead heading it and keep the N20 PSI the same thru the run using a N20 regulator keeping the bottle pressure high then taking it down to 900 then NEVER run it rich it kills motors lifting ring lands from the fuel getting under the rings. I am also going to swap out the fuel pressure regulator with a Mallory or aero one next week. If you calculate your fuel pressure needs per injector size for estimated HP of engine you should know pressure needed. A faulty regulator can not only leak gasoline, which is a potential safety hazard, but can also cause performance issues as well. I imagine just strictly looking at the fuel system, there are really only four main components: Fuel pump, fuel filter, pressure regulator and TB injector. installations it is possible to mount the regulator directly to the TBI fuel fitting using an elbow fitting. The Holley TPI adjustable fuel pressure regulator kit will reuse the torx screws and base. The shiny little thing right before the distributor is the fuel pressure regulator, that was the old TPIS AFPR I had. The GM TBI is internally regulated and has a return line already virtually making the external regulator useless. Oh well At least I got to clean. They are not as sensitive as a 40 - 60 psi MPI system, and the regulator is less complex. With the 80lb BBC injectors and a walbro 255 fuel pump. As long as the fuel pump is not operating, the TBI fuel system components can be removed without the need to release the fuel system pressure. Loosening the screw. You can either check the adjustment during the five second "Fuel Pump Prime" time (in Engine Parameters), or temporarily jumper wire the system relay (terminals #30 & #87), so the pump runs continuously (so you have time to adjust it). A bypass regulator restricts the flow, forcing pressure up before allowing fuel to return to the tank, creating fuel pressure and then maintaining it. if the tbi ecu could sense boost, it would automatically adjust the air/fuel ratio, but thats out of the ecu's ability the good thing about a tbi is that they are ther most upgradeable fuel system offered on a stock 4. This one was spawned by Azscoobie in a thread a few weeks back about increasing fuel pressure and gaining headroom in your fuel system. ), which can be hard to find for larger engines - Holley has made a 4bbl TBI for years (in 650, 700 and 900 cfm sizes),. The 58502 operates within a 2-4 psi pressure range, and an adjustment mechanism with fine thread pitch allows for precise fuel pressure adjustment. As long as the fuel pump is not operating, the TBI fuel system components can be removed without the need to release the fuel system pressure. External high pressure in line fuel pump; Mustang/Capri T/C- 100L or 26. A fuel pressure regulator is a device that is used to control the upper limit of the fuel pressure. Where is the TBI fuel pressure regulator located at in a 1995 Chevy s-10 4. Name 56503 High Flow Fuel Pressure Regulator. The JET TBI Billet Aluminum Adjustable Fuel Pressure Regulator provides you with the ability to adjust fuel pressure for maximum efficiency and horsepower gains. Classic symptom that the regulator needs replaced. The Atomic Adjustable Regulator is configured for a single -6AN inlet, and dual -6AN outlets (for regulator-to-tank line routing. In addition, pull the hose off the back of the regulator and see if there is fuel in the line which would indicate the regulator has failed (Note: this is not a vacuum line it is simply a "drain" in case the regulator fails). The regular ones and the “Security” ones. shipping world wide, 24H deli. There is an adjustment screw inside which is held in place with a large spot of solder. Connect fuel pressure gauge to fuel body pressure test fitting. We were unable to adjust the fuel pressure below 18 psi at WOT (Wide-Open Throttle). Ghetto Wagon 50,771 views. ECU has no control over fuel pressure relief valve. Start the engine and let it reach operating temperature. The higher pressure pump (e2000) can put out 60+ psi and a worn out regulator (even TBI) will have a hard time holding it back all the time. The TPS sensor will be part of the TBI (as will the fuel pressure regulator). 64 hp per liter. If you check fuel pressure, be sure to use a low. Item-details FUELAB® 565 Series Fuel Pressure Regulators have all of the same great features as our 515/525 Series except for extreme capacity. A fuel pressure regulator is an integral part of a vehicle's fuel system. ACDelco 217-389 17112907 TBI Fuel Pressure Regulator Cover GM 220 Throttle Body. MPI Fuel System Pressure Test. These things are very sensitive to fuel pressure issues. For those who have early TBI, here's something. I found out mercruiser had a recall on the fuel regulator on the cool fuel. Remove the aluminum plug with a small punch and hammer. 5 tbi pump may not have enough volume to run the 5. I am guessing once I get some logs hopefully can narrow down the possibility. They are not as sensitive as a 40 - 60 psi MPI system, and the regulator is less complex. 0L MPI, 350 Mag MPI & MX 6. Name 56503 High Flow Fuel Pressure Regulator. if i get an inline. Also essentila is a good fuel filter. TBI fuel injection is a type of fuel injection system where the fuel is injected into the throttle body. 5 - 6 psi of fuel pressure will work sufficiently. Min voltage is 10v. 0 GXi, I was doing a lot of reading and came across the service bulletin P-23-7 no. I'm seeing 14psi+ from both regulators. com FREE DELIVERY possible on eligible purchases. The fuel pressure gauge should jump up to your system pressure, in most cases 45 p. The tbi is rated at 9-13 psi from the factory, but with some modifications, they run better at around 14. The GM TBI is internally regulated and has a return line already virtually making the external regulator useless. There is a "plug" in the bottom of the regulator that blocks the adjustment of the fuel pressure. Fuel pressure specs for any GM TBI Ive ever dealt with is 9-13 PSI. 7 injector to 28psi and you will run out of air long before you run out of fuel even with the 454 TBI. These JET adjustable TBI billet fuel pressure regulators ensure that your vehicle's fuel supply is precisely metered for optimum mileage and performance. The built in regulator will fight to maintain this. Ensure the fuel pressure been properly adjusted and "Actual System Pressure" (Terminator - "Fuel Pres") accurately entered in Engine Parameters. Adjust your fuel pressure for maximum power. 7L, 1982-1984 Corvette Crossfire Front and Rear. They are not as sensitive as a 40 - 60 psi MPI system, and the regulator is less complex. Fuel Pressure Regulator Replaces: Mercruiser 885174 Fits: MCM/MIE 4. I cannot find replacement lines anywhere since it is the only year of TBI and I do not know what to do. Again, if you notice even a slight issue, it’s important to have it checked to correct any problems fast before further damage can be inflicted. A fuel return line is essential, and must be included in your fuel tank/delivery setup. 3 thats not a sy/ty. A running TBI engine will have 14-15 psi. It will mention the exact kind and variety of fuel pressure injection system that is used. Watch which way the tab goes, up is more pressure. If Rest Pressure drops too quickly, check for leaks at o-rings and fuel line. The throttle looks like a carburetor without the fuel bowl, the metering jets or the float. Re: TBI Adjustable Pressure Mod I don't think you understand what I'm attempting to ask and I don't know the correct termmanology to ask another way. Find JET Adjustable TBI Billet Fuel Pressure Regulators 61500 and get Free Shipping on Orders Over $99 at Summit Racing! These JET adjustable TBI billet fuel pressure regulators ensure that your vehicle's fuel supply is precisely metered for optimum mileage and performance. Fuel Pressure Regulators. Downstream from the fuel injector is a back-pressure regulator which maintains pressure (usually 30-45 psi) all the way back through the fuel rail to the fuel pump. CAUTION: When removing-screws from pressure regulator cover hold pressure against the compressed spring. At idle, turn regulator adjusting nut clockwise to increase fuel pressure. Jet Chips Fuel Pressure Regulator - TBI Fuel Pressure Regulator Kit - Incl. I assume it would work. It is designed to keep the fuel line pressure at a consistent value, allowing for smooth operation of the engine. The pressure regulator has one of the most important jobs in the system: Control the. But the engine is still stalling out and running rough at low rpm and will barely idle. 52; Buy It Now +C $25. Another symptom of an issue with the vehicle's fuel pressure regulator is fuel leaks. I recently did the heads on it and while putting everything back together replaced the stock fuel pressure regulator with an adjustable unit from Jet. (More than any other single thing about them, the advantage of any FI system is the fine super combustible air/fuel mixture it creates. 1994 and 95 years use a roller vain type pump rated at 210kpa (30psi). Generally to set your fuel pressure on the W. With the vacuum line OFF the fuel pressure regulator, screw the adjustment screw in until the gauge reads 44 psi. 1994 and 95 years use a roller vain type pump rated at 210kpa (30psi). Vacuum compensation port WARNING!. If the test is done with a method that allows the fuel filter to be in place, a dirty filter can also cause low pressure. A running TBI engine will have 14-15 psi. I now get 40+psi fuel pressure when turning on the key. The tbi is rated at 9-13 psi from the factory, but with some modifications, they run better at around 14. The built in regulator will fight to maintain this. fuel pressure regulator is on top of. You can mod your regulator to make it adjustable and set it where the computer expects it. They sell adjustable fuel pressure regulators to adjust it up or down a few psi and since the stock regulator is set at the factory and non adjustable, I thought that if the regulator was starting to. If you experience hard starts especially restarting a short period after shutting off the engine, then one possibility is a leaking fuel system. Fuel Pressure Regulators. At 3/4 to WOT the computer uses a fixed program for max power. I recently did the heads on it and while putting everything back together replaced the stock fuel pressure regulator with an adjustable unit from Jet. At idle, turn regulator adjusting nut clockwise to increase fuel pressure. TBI fuel injection is a type of fuel injection system where the fuel is injected into the throttle body. But the engine is still stalling out and running rough at low rpm and will barely idle. There is an adjustment screw inside which is held in place with a large spot of solder. 1988 Chevy S-10 Need help with 4. Made from tough, rigid material. Remove spring and diaphragm assembly (22,23,24) NOTE: Whenever pressure regulator cover is removed, the diaphragm must be replaced to prevent. ), which can be hard to find for larger engines - Holley has made a 4bbl TBI for years (in 650, 700 and 900 cfm sizes),. REPLACEMENT FUEL PRESSURE REGULATOR. About 40% of these are Injector Nozzles, 0% are Fuel Pump & Parts, and 11% are Other Auto Engine Parts. Squirrelly problem. The built in regulator will fight to maintain this. Notes Will support engines up to 525 horsepower. Note cell number RPM 2000 MAP 70. When testing fuel pressure may vary slightly but should be pretty close to spec. Air Fuel Control The Stoichiometric mixture of 14. Holley 12-804 Adjustable Fuel Pressure Regulator, 1-4 PSI. A pressure regulator maintains the correct injector pressure. So another option to consider would be to run EBL and a VRFPR (vacuum referenced fuel pressure regulator) with a fuel pressure setting of 22 PSI. Note: To keep cleaner fluid from going back to tank, block the fuel return line or adjust the regulator to run vehicle at 5 PSI under fuel pressure specifications. Remove air filter elbow and hose. ACDelco 217-389 17112907 TBI Fuel Pressure Regulator Cover GM 220 Throttle Body. 7 TBI fuel injected? It is bolted in the very top of the TBI housing behind the 2 injectors. I used some double-jacketed fuel line from Jegs (push lock type) hose at the back of the TBI on both the feed and return lines and run a cheap Summit 0-30 fuel pressure gauge. EFI=Electronic Fuel Injection The problem was that the TBI was getting way too much fuel (fuel pressure) and was flooding the engine. I really believe you have a bad fuel pressure regulator or the wrong fuel pump. and fuel system pressure. I now get 40+psi fuel pressure when turning on the key. TBI fuel injection is a type of fuel injection system where the fuel is injected into the throttle body. Misfires and a decrease in power, acceleration, and fuel efficiency. If there is a pressure regulator problem, the pressure regulator fits within the bowl beneath the fuel inlet. When I turn the ign on with the fuel pump running, the pressure goes way too high. If your fuel pressure regulator is set for 13 psi it will let the pump build 13 psi and let any excess fuel flow go back to the tank via the return line. Again, if you notice even a slight issue, it’s important to have it checked to correct any problems fast before further damage can be inflicted. CHEVROLET > 1993 > S10 BLAZER > 4. Sniper fuel pressure regulators are designed to adjust for fuel pressure requirements of various carburetors. The idle its a process of key cycling and a jumper wire in the ADL connector before actually setting the mechanical set screw on the throttle. JET Fuel Pressure Regulator Kit 38-1937 JET Performance Adjustable Fuel Pressure Regulator Kit is a direct replacement for factory unit and contains a billet adjustable fuel pressure regulator with a steel insert on adjuster to prevent stripped threads. The fuel pressure regulator fits a lot of your problems. This feature allows you to match a particular engine's breathing capability with an optimum fuel pressure setting. 0 kPa or 39 psi (system pressure controlled by pressure regulator on engine) Internal relief valve overpressure limit- 950 kPa or 138 psi Low pressure pump is to provide pressurized fuel to the high pressure pump. If the test is done with a method that allows the fuel filter to be in place, a dirty filter can also cause low pressure. Remove the installation bolts (E), and then remove the high pressure fuel pump from the cylinder head assembly. Adjust your fuel pressure for maximum power. Also, there may be a blockage in the supply line or leakage in the return line. 7L TBI equipped pickup or SUV since they don't come equipped with a Schrader valve. If this is your first visit, be sure to check out the FAQ by clicking the link above. This will also allow for a much shorter return line and simplify the installation. Under these conditions you would have zero or negative fuel pressure. Someone put the wrong ones on my motor and I wound up with 50 lbs pressure at the tbi. Engine stalls when you come to a stop, after the engine warms up. Putting in a regulator in before the TBI is not accomplishing anything. 7L, 1982-1984 Corvette Crossfire Front and Rear. However, if you are planning on a throttle body injection set-up, you need a dedicated TBI unit (in order to supply the fuel to the injectors, etc. from it tells the computer how to adjust the air/fuel. Misfires and a decrease in power, acceleration, and fuel efficiency. Unlike the fuel pressure regulator on the O. tester and reconnect all 10. The PWM fuel pump is engineered to operate without an external fuel pressure regulator. Notice how the volume of fuel delivered drops to 42 ml. Adjusting A Fuel Pressure Regulator "How To" ⛽️. Ultimate (TBI) Mod, making stock fuel pressure regulator in GM #220 throttle body adjustible While installing a new fuel pressure regulator diaphragm in the Rochester #220 throttle body of my 93' GMC Sierra (SLE) Z-71 with a 5. It is quite easy to calculate the new flow rate of an injector when adjusting the fuel pressure. Fuel System Checks Fuel Pressure is critical to the operation of a fuel injection system. The lower that pressure can be, the less it affects the pressure in the fuel rail(s). There will be a diaphragm and a spring under the housing. The fuel pressure regulator kit. To remove Fuel Pressure Test Gauge, reverse steps 6 through 1. A faulty regulator can not only leak gasoline, which is a potential safety hazard, but can also cause performance issues as well. If not held firmly it may cause personal. Typically, this starts and ends in the fuel tank, and utilizes one or more pumps to supply a high volume of fuel at high pressure to the injector rail. A returnless fuel system uses an in-tank pump and regulator. The fuel pumped by the fuel pump must be at enough volume and pressure to overcome the spring pressure; the excess is sent to the return line back to the fuel tank. Fuel System Checks Fuel Pressure is critical to the operation of a fuel injection system. Therefore,since it i. Fuel pressure specs for any GM TBI Ive ever dealt with is 9-13 PSI. Your pressure should be right on the money though BigRay. At idle remove the vaccum hose and the fuel regulator will rise to its highest setting. TBI pressure regulator spring question Im in search of a regulator spring for the stock tbi regulator that has been made adjustable. If you end up replacing your fuel pressure. A running TBI engine will have 14-15 psi. A sooty spark plug could just mean the engine is burning oil at that cylinder. Try pulling the fuse for the fuel pump to see if it will run for a short period of time. I would bet that if you can hear the fuel pump running, it is the regulator, and here is why: TBI systems run a similar pressure to a Carb - about 7psi. The same principle of operation applies. Crank the engine for several seconds. The Sniper uses four 100-lb/hr injectors and will feed up to a 650hp naturally aspirated engine. While testing will need to be performed to verify the failure,. to your engine backfiring or the smell of fuel when you decelerate your vehicle. You could try this setup before buying a new TBI unit. I use a fuel/air ratio monitor permanently installed. Fuel Injection Systems Speedmaster™ line of EFI systems is all you need when deciding to upgrade your engine to modern electronic fuel injection. One of the mods was putting in a new jet fuel pressure regulator, so I can adjust the pressure if I need to. If the test is done with a method that allows the fuel filter to be in place, a dirty filter can also cause low pressure. The adjustment knob is accessed under neath the rear flange behind the throttle body. I am still trying to survive with mine mounted on the frame. The typical EFI fuel system uses 40psi fuel pressure across the injectors. 7L, 1982-1984 Corvette Crossfire Front and Rear. After the second visit, they found that the Holley regulator is inconsistent at holding fuel pressure. Loosen the jam nut on the front of the unit. Everything includes the Tanks Inc tank with internal electric fuel pump. The thing is VERY hard to adjust. All we have to do is install the fuel pressure gauge in between the pressure regulator outlet and the nitrous jet. A restricted return line could conceiveably cause noisy injectors due to high fuel pressure I suppose, but I'd think the high pressure would be more likely to cause the thing to run rich rather than just make the injectors noisy.