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Discussion Starter · #1 ·
S10 Owners:

I have a 96 S10 with 80k miles that has developed
a "cold start" problem after sitting for serveral hours. Note: I'm in California so minimum temperature is still in the 40's!

I can get it to start normally by turning the ignition to ON a couple of times before actually cranking the starter ...which seems indicative of losing fuel pressure while sitting.

Sure enough, a gauge on the fuel rail reads 60 PSI with the ignition ON ... but this drops to 0 PSI within 2 hours of stopping the engine. I can't find a spec for pressure loss, but this seems like an abnormal rate of pressure loss. Does anyone know how long fuel pressure should hold or what a "normal" rate of pressure loss would be?

Since I can't find any external leakage, it seems that either:
(a) fuel is leaking back into the tank through a faulty check valve in the fuel pump (or through something called the pulsator?)
(b) fuel is leaking "forward" through the regulator and injector poppet valve.

Are there other possible places to look for leaks?

Can I differentiate fuel pump from injector leakage by pressurizing the system with fuel and then clamping the flexible fuel hose near the inline filter to prevent leakage back through the fuel pump?

Are there other things to be checked?

Thanks for your consideration,


I'd Rather be Blown than Injected
251 Posts
It is normal for the pressure to drop back to 0 psi when shut down. When you turn the key it energizes the pump for a few
seconds to pressurize the system and then the pump runs all the time when the engine is running. Do you have full pressure when
the engine is running? If so all well, or do you have some kind of a problem?

Self Portrait
1,634 Posts
Wicked X is correct

You have a schrader valve in your system that relieves the pressure on your system I can't find what your pressure should be, my book stops at '92. But on a 93 is sheould be 35-38PSI.

Hope this helps!

'92 S-10 Tahoe 4.3L Bone Stock
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