Fuel Pressure in 99 Tahoe LQ4 swap help!
08-08-2010, 01:04 PM
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Fuel Pressure in 99 Tahoe LQ4 swap help! I have a '99 2 door tahoe that I just swapped an '02 LQ4 into from a 2500HD Silverado and am having fuel pressure problems. I have hooked a fuel pressure gauge up to the shrader valve and on startup the pressure peaks to around 50psi and then it will run for about 10-15 seconds and slowly sound like it's gonna die until it shuts off it gets down to 18-20psi. So at this point I thought it was a faulty fuel pump so I replaced that yesterday along with a new fuel filter and new fuel pressure regulator and it still does the same thing. The injectors that came with the motor weren't good so I got some used off a guy who had a LQ9 so I know it's not an injector problem either.
I am so stumped it is making me so mad, I've tried damn near everything and still can't seem to get it. Any ideas or help would be greatly appreciated!
I am so stumped it is making me so mad, I've tried damn near everything and still can't seem to get it. Any ideas or help would be greatly appreciated!
08-08-2010, 01:22 PM
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the pressure for that engine needs to be 55-62 psi. since you have replaced all of that stuff with no change i would look at a voltage drop or just a low voltage or bad ground on the fuel pump circuit that could be cutting the voltage down to the pump after start up. the factory 99 pump should be well cappable of supplying that engine.
08-08-2010, 01:59 PM
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the pressure for that engine needs to be 55-62 psi. since you have replaced all of that stuff with no change i would look at a voltage drop or just a low voltage or bad ground on the fuel pump circuit that could be cutting the voltage down to the pump after start up. the factory 99 pump should be well cappable of supplying that engine.
08-08-2010, 02:11 PM
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wouldn't hurt
12-08-2010, 06:10 PM
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does fuel have anything to do with vats?
Vehicle anti theft system.
there is a bypass mod box.
or it can be written out of the pcm by a tuner erasing it.
Q; any pictures of your swap and more info? looking into doing one myself.
Vehicle anti theft system.
there is a bypass mod box.
or it can be written out of the pcm by a tuner erasing it.
Q; any pictures of your swap and more info? looking into doing one myself.
