I'm chasing a loss of fuel psi, when key is turned off. [130,000 mi vehicle.]
So far, I've found a couple injs leaky, but not serious enuf to cause an immediate drop to near zero...[<2 mins and it's over!].
Thus far:
1. I've cleaned the injectors. Were NASTY!
2. Replaced the fp regulator.
3. Replaced the filter.
I'm thinking it's down to the check valve in the pump, has taken a dump.
The psi at/near 0, key on, engine off, it takes 2-3 cycles to get psi up to op pressure. If I go directly to start, it takes considerable time to raise the psi far enuf to start.
I've scanned it w/ Flashscan.. no codes, and all parameters look good.
I've seen some postings on other boards, about GM truck pumps being a problem....electrical or??
Can someone confirm the exsistence of the check valve, B4 I drop the tank?