Full Answer
How much HP can a stock 75lph TBI fuel pump support?
First I start with a new Fuel pump, STOCK 75lph TBI fuel pump will only support about 230hp before the fuel pressure drops like a rock.
How much fuel pressure should a TBI injector have?
These late-'80s and early-'90s TBI injectors are intended to run at between 11 and 13 psi, although it's typical to see the pressure down around 10 psi. Generally, a 1-psi change in fuel pressure—from 11 to 12 psi, for example—can be worth roughly an additional 4 percent fuel flow.
How much HP can a stock TBI make?
It's possible to make around 275 hp with a stock TBI unit, so rather than go nuts on a heavily modified TBI, I'd suggest you start by making sure the existing TBI unit and injectors are in good shape. The actual throttle plate diameters for the 4.3/5.0/5.7L TBI units are all the same at 111/16 inches (big-block TBIs are 2 inches).
What is the fuel pressure on stock 350 truck injectors?
Stock 210hp 350 V8 up to 250hp the stock 55lb 350 truck injectors at the factory 11-12psi is fine. from 250hp to 260hp the fuel pressure should be bumped up to 13-14psi on stock 350 truck injectors which will change their flow rating to 60lb/hr
How much power can a stock TBI handle?
around 275 hpStock small-block throttle bodies only flow around 500 cfm (compared with a stock Q-jet that flows 750 cfm). It's possible to make around 275 hp with a stock TBI unit, so rather than go nuts on a heavily modified TBI, I'd suggest you start by making sure the existing TBI unit and injectors are in good shape.
How much HP does a fuel pump add?
Making the ChoiceFuel Pump Free FlowCarbureted EngineFuel Injected w/ Power Adder50 gph/190 lph600 hp400 hp67 gph/255 lph750 hp500 hp90 gph/340 lph1000 hp600 hp125 gph/470 lph1300 hp800 hp2 more rows•Nov 26, 2019
What is the fuel pump pressure for TBI?
The fuel pressure regulator is set for approximately 12 psi (30 psi on '94 & '95 BBC trucks). With a service range of 9 to 13 psi being considered good.
How much HP can a TBI make?
Stock TBI unit can make about 330 HP at its best with normal compression and cam design.
Does changing fuel pump increase horsepower?
The technical answer is yes; fuel injectors can add 10 extra horsepower at peak. However, for some car owners, that minimal difference does not offset the increased cost and complexity of switching to fuel injectors or upgrading the existing stock fuel injectors.
Can a fuel pump be too powerful?
Using the wrong fuel pump that delivers excess pressure can cause problems ranging from poor performance and lower gas mileage to flooding and carburetor damage. When the pressure is only a little over the required amount, your vehicle may sputter when you first accelerate from a stopped position.
Is TBI better than a carburetor?
So most TBI systems can tolerate radical cams with durations up to about 250° with much more finesse than a carburetor. The engine will run smoother, idle better, start easier and provide better throttle response and cold driveability with TBI than a carburetor.
How do you check fuel pressure on a 5.7 TBI?
0:566:40Quick and easy fuel pressure test (gm tbi) - YouTubeYouTubeStart of suggested clipEnd of suggested clipAnd it may be the same type thing. But the male end of this adapter goes into the filter and theMoreAnd it may be the same type thing. But the male end of this adapter goes into the filter and the female end goes into the line coming from the tank. And then you hook your gauge right here.
How do you adjust a TBI fuel pressure regulator?
9:2114:14Ultimate TBI Mods: Adjustable Fuel Pressure Regulator - YouTubeYouTubeStart of suggested clipEnd of suggested clipIf it's not very clear you can adjust the fuel pressure by screwing the red knob up or down to clearMoreIf it's not very clear you can adjust the fuel pressure by screwing the red knob up or down to clear the screw we need to bend this vacuum line just a little.
What is it like living with a TBI?
Every individual's experience with traumatic brain injury is unique, but there are many common symptoms and emotions. Anger, fear, sadness, and anxiety may be accompanied by difficulties with memory, pain, and the challenges of maintaining relationships.
Does TBI get worse with age?
The short answer is yes. Some brain injuries do get worse over time. Secondary brain injuries are complications that arise after the initial injury, such as hematomas or infections.
Can you put Vortec heads on a TBI 350?
If you wanted the Vortec heads on your engine then you would have to buy a new intake manifold to be able to get the TBI set-up onto the heads.
What is a TBI?
The GM TBI is a speed-density system, which assumes the engine ingests a given amount of air at wide-open throttle (WOT). Mass airflow systems measure the air entering the engine, but speed density systems like those used on these TBI engines do not.
How fast does a wide open throttle increase fuel pressure?
You should test any fuel pressure change with a WOT acceleration run in Second gear from about 30 to 60 mph.
Can a Vortec head make 300 HP?
These heads flow very well and would be a good choice to make 300 hp with a mild camshaft. However, the Vortec heads use a different intake bolt pattern that does not match up to the TBI intake manifold. There are ways around that by using a GM Performance Parts aluminum intake that bolts to the Vortec heads and features a stock mount for the TBI.
Where is the fuel pump located on a 1995 4.3L?
As you're already aware, the throttle body fuel injection system on your 1987 to 1995 4.3L, 5.0L, or 5.7L pickup (or SUV) uses a low pressure (12 PSI) electric fuel pump located in the gas tank. And although GM did not include a Schrader valve to which you could connect a fuel pressure gauge, it can be tested with one to find out if ...
How to tell if fuel pump is bad?
A bad fuel pump will make your 4.3L, 5.0L, or 5.7L throttle body fuel injected pickup or SUV crank but not start. Here are some more specific symptoms: 1 The ignition system is creating and delivering spark to the spark plugs. So you know that the ignition system is not at fault (in other words: the ignition control module is OK, the ignition coil is OK, etc.). 2 You've sprayed starting fluid (or carburetor spray) into the throttle body and your vehicle started, even if only momentarily. 3 You don't hear the fuel pump making a buzzing sound as you turn the key to the On position or crank the engine. 4 You don't see the fuel injectors spraying gasoline.
What to do if injectors are not spraying fuel?
If the injectors are not spraying fuel, then the next step is to coax the engine into starting using starting fluid. CAUTION: You'll be working around a cranking engine, so take all necessary safety precautions and think safety all of the time. OK, to get this show on the road, this is what you'll need to do: 1.
How to test if a pickup has no fuel?
TEST 1: Using Starting Fluid. The first step is to see if a ‘no fuel’ condition is actually the cause behind your pickup or SUV's no start problem. And the fastest/easiest way to do this is to see if the fuel injectors are spraying fuel while a helper is cranking the engine.
Can you hear the fuel pump buzzing?
You've sprayed starting fluid (or carburetor spray) into the throttle body and your vehicle started, even if only momentarily. You don't hear the fuel pump making a buzzing sound as you turn the key to the On position or crank the engine. You don't see the fuel injectors spraying gasoline.
Can fuel injectors spray gasoline?
You don't see the fuel injectors spraying gaso line. Although the above list is a not a very complete list of symptoms, the theme that runs thru' them, and any other related symptom, is that the engine will crank and crank, but not start.
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Question
I have a 95 GMC K1500 with the 5.7L TBI. 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. I noticed that the only publicated pressure recommendations I can find are that it should be between 9-13 PSI with engine off and pump on, I believe.
What is the worst flowing head GM has ever released?
The Heads. The TBI heads are the worst flowing heads GM ever released. If your rebuilding the motor, don’t waste ANY money on those pitiful poor flowing TBI heads. Valve springs and a good magnaflux and valve job will cost you a couple hundred or more and that money could have been spent on decent new heads.
Why do stock camshafts last so long?
The only reason the stock camshaft lasted as well as it did was the very low duration and lift of the cam as well as the very weak valve springs. Once decent valve springs and decent cam are used the zinc issue becomes and issue. So I really never recommend a flat tappet cam in a new engine build.
Does a camshaft have a vacuum?
A performance camshaft will typically produce a lower vacuum signal than the stock engine/camshaft, and the stock PCV valve may not close enough at idle, which can cause an irregular and/or high idle, or otherwise not function efficiently throughout the operating range of the engine.
Does a 210cc intake runner make good horsepower?
While a 210cc intake runner head will make good horsepower on a 350 engine its not going to make good low end torque. now with a 400ci SBC that 210cc intake runner will work just fine as you have 50 more cubes to pull air down that runner.
How do I know what flow rate I need?
Minimum flow rate needs can be calculated by multiplying peak horsepower by BSFC. This will give you fuel usage in lbs./hr. For example:
Flow Rate vs. Pressure
Fuel pumps are usually advertised by their free flow rate. This is the flow rate with no pressure. As pressure goes up, flow rate goes down. The best way to find the flow rate at a given pressure is to check a fuel pump’s curve chart.
Electrical Considerations
The chart above shows a couple important things about an electric fuel pump. Flow rate increases with voltage and amp draw increases with pressure.
Making the Choice
A fuel system with a Return Style Regulator or a Non-Return Style Regulator can use a bigger fuel pump than you actually need with no problem.