All,
I'm in the last ditch effort to figure this problem out before the truck gets a "for sale" sign.
89 5.7L V8 swap, 5-speed.
Finally had a chance to test the fuel pressure, while hot, while WOT.
It goes down to like 1 PSI. Otherwise, I get a strong, steady 10 or 11 PSI, while the engine is cold.
No codes right now. What should I be looking at?
Sir,
Pressure dropping due to demand is a fuel quantity 'volume delivery' issue.
Assuming (for a moment) a good fuel pump, I'd specifically look for:
* a smashed/kinked fuel line anywhere from tank to TBI inlet.
* a dirty fuel pickup inlet filter (sock) in the tank inhibiting flow.
* Rerun your test with the gas cap temporarily loosened/removed from the filler opening.
If none of the 3 items above change the fuel pressure at WOT, then we basically have
no choice but to head in the direction of a fuel pump with inadequate flow. The question
now becomes, is the pump the perpetrator or a victim?
* Pump is always running slow due to excessive voltage drop while it is running. Still runs
fast enough to support light demand, but not enough to support WOT operation. Could
be either a bad ground, bad +12v connection, or both. (Fuel pump as victim.)
* Pump is working as advertised, but there's an internal leak between pump outlet and
tank outlet. (Think critical volume spraying out inside tank instead of going towards the
TBI injectors.) This failure has been documented by others in this forum. (Fuel pump as victim.)
* The fuel pump is no longer working to specification. Think missing sock from short-sighted PO
allows debris into pump, and internal clearances are now out of tolerance, reducing pump performance.
(Pump is perpetrator.)
****
As to whether to keep the truck or divest it, if the thrill is gone then I can understand selling it.
1) You could troubleshoot & fix this issue, sell it, basing the asking price off the fact that
it runs well, has new parts in the engine bay + the fuel delivery system is known-good, etc.
2) Or you could decide that you've had enough, sell the truck as-is, including letting the potential
buyer that you have a WOT fuel pressure issue. No risk to the balance in your karma bank account.
3) Sell the truck as-is.
Not sharing what you know is wrong. Rely on Buyer Beware philosophy.
I would be uncomfortable with this. Even though others have done this to me in the past.
Mom would be disappointed in me. :0)
****
The bottom line is that try as you might, you will remember this truck for the rest of your life. So
make your decision and implement it in such a manner that you feel the best way possible about this
life lesson.
Here's hoping you at least try to figure this out before you decide to either keep it or ship it.
