CorvetteMike2024

I have an 89 L98 motor. I have hard starting in the morning. After its running, it starts fine.

When I turn the key on, it only goes to 30 psi on the fuel rail. During starting, it stays at 30 until it starts ahd holds 42 while running. It runs fine once started. When I turn the key off, the pressure drops quickly.

I installed new fuel injectors about 3 months ago.

I have the FSM. Im looking at the A-7 chart on 6E3-A-21.

2 possibilitys. Regulator and fuel pump. I purchased this car new and have never changed out the regulator. 300k + miles on it.

It says to pinch off return line to tank to check regulator. Where sould I pinch this line off at? Your thoughts on pump or regulator?

Thank you for your replies.

leesvet

Both.

The pump is junk, that's a given,. The bladder in the regulator gets hard after years of blended fuels. The disc in the reg that does the sealing wears also.

30 psi at Key ON is not enough. It should be 40-42psi then drop to 38-40 when idling. The system should also hold pressure for hours....at least hold 30 to 40 psi for the 1st hour then drop a few psi each hour after until it gets to under 20 where that should take all night to fall off.

Red86Z51

If you decide to replace the regulator, be sure to read my thread on new defective regulators here --> New Fuel Regulator Diaphragm DEFECT Alert!

It's info that could save you some grief.

leesvet

YES ! ! ! !

ABSOLUTELY !

look at the new regulator when you buy it. IF it looks like a textured material, or like rubberized fabric, leave it on the counter and go to the next part store.

The diaphragm should be a thin rubber that's got no cloth or fabric in it, anywhere. Some of these are a cheapo clone probably from China or Mexico where their 'copy' of the real part is using some lesser quality material or technique.

The metal surface of the disc and the seat should also me shiny smooth, a machine smooth that's also mirrored. NOT with grooves or texture. They leak. They can leak internally and cause hard starts, low pressure and fast leak down. The bad diaphragm can leak externally and cause car-b-ques

I've seen these defective parts and I can tell you its not a joke. For $75 it better be the real thing !

WW7

TPIS has diaphrams for $41.95 , hard to beat the price.....WW

http://www.tpis.com/parts/view/15
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CorvetteMike2024

I did the leakdown test with the return line pinched at the tank. No change. I installed a new fuel pump and it starts right up now. Thank you for your replies.

PLRX