fuel pressure regulator 1998 Jimmy SLS 4.3

[Tim]

I checked the fuel pressure regulator on the above engine and it read 44 to 45 psig. After shutting off the key it remained at more than 40 psig for about two hours and then slowly (very slowly dissipates. It doesn’t seem reasonable that it would hold 44 psig forever but the problem of not starting after several hours of shut down seems to equate to no fuel pressure until engine has been started at lease once. It used to be that if I didn’t start it every day this situation would occur but now it’s more frequesnt. What’s my next step? Please and thank you. Tim

Topic

[Ty]

This is called a leak down condition.

Just for a test after the truck has set long enough that you know you will have trouble starting it turn the key to the run position three to five times then try to start it.

If it starts more like it should you will know there is a leak somewhere but where is the question.

Are you smelling any raw fuel under the hood or anywhere around the truck?

[Tim]

Definitely tales several attempts to start vthanksersus one long cranking attempt. It really runs great after it finally starts. And Yes! While attempting to get it started there is a heavy gasoline smell.

[Greg]

The fuel pressure regulator is inside the intake manifold. You may want to remove the upper intake and turn the key on and off a few cycles and see if you get fuel pooling in the intake from either a bad regulator or a compromised fuel injector line to one or more injectors that are also inside the intake.

[Andrew Harris]

Your fuel pressure is to low. System calls for 60-66 PSI. Fuel pressure is very important on this system. It must be at least 60 PSI. This system uses poppet type valves inside the intake manifold that rely on this pressure to be opened. The spider injector assembly as some call it is known to leak fuel inside the manifold. There is an updated “spider Injector” kit that eliminates the poppet valves and converts them into regular injectors. Fuel pressure is still low though probably due to aging fuel pump.

[Tim]

This critical diagnosis with not only what but also why – is of great value to me. You’ve saved me the cost of membership many times over. Many thanks.

[Author]

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