my 95 jimmy has a bad hesitation under load
it is a eary cmfi truck.
most of the tuneup parts were replaced not long ago
so
i threw a fuel pressure gauge on it and it pumped up to 65
then it dropped like a rock fast.
i yanked off the intake.
it looked washed on the pass side.
so i changed out the injection pressure reg.
recheck the pressure..still drops fast..
now i carefully pulled 3 poppets out off of one side
pressured up system.. no leaks
then i put them back
and did the same thing to the other side -no leaks there either.hmm

so after all of that,would it be safe to assume
my loss of fuel pressure is the fuel pump check valve in the tank?

i was close to getting a spider untill i searched out a few threads here
that have helped me out alot!

 

do you have a leak on the fuel lines into the spider? if not probably check vale. im fighting with my 95 at the moment pressure regulator and fuel lines bad

 

i have no fuel leaks anywhere that i can see.
even when pressuring up the system with the intake off.
at 65 lbs and losing pressure that fast
it has to go somewhere..
i think it has to be blowing right back into the tank??

the tank pump is less then a yr old
learning another lesson on not using oem parts i think! lol
the pump is a bosch.

 

So many questions. I have one of these myself, so trust me I can relate. How long have you had this puppy and when did the problem start. One thing you have going for you is a new AC pump on this model is only $50 bucks. Has the fuel pump ever been changed?


Clean shiny spots under plenum never good but pass side is better. Know your next thing is your FPR, but you changed that, however they only leak under the vacuum of the plenum unless you spray some compressed air on the little hole. No more then 10psi or you will rupture the diagram. Then another 50 to dorman.


OK have you ever checked the pressure at the filter. Key on engine off, should hold at least 70psi, your reg opens at 61.


Wait theres more. You have an old time filter. No quick disconnect. To connect the filter to the gage you will need a dorman fuel filter repair kit, don't stress $4.95.











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the truck has 310k miles owned it for 280k of that
it just started doing this the past few days
the truck usually runs well.

i guess off to the parts store to get that adapter
so i can chase this fuel pressure loss down.