96 460 runs good til 1/2 throttle, hard starts.
#16
09-19-2012, 09:55 PM
#17
09-19-2012, 10:30 PM
Ran the truck with the pressure gauge hooked up at WOT and through the range. PSI drops to about 20 straight away. It never goes below 20 though then returns to 32 as soon as you let off. Tried key on engine off pressure and it went to 20PSI before pump shut off, it would go all the way to 40 and hold when I cycled the pump. Also tried with the vac line off the FPR while running. It bounced a lot and would only even out at WOT and held 20PSI. I would assume this would bolster the weak pump thoery????? Or possibly a leaking fitting at the pump??????
Sorry to ask so much info but these pumps are expensive and though I have 2 good ones it's not a job I enjoy.
Sorry to ask so much info but these pumps are expensive and though I have 2 good ones it's not a job I enjoy.
Verify it holds pressure within 5 psi of spec for after turning power to pump off. We know its not to spec but does it drop right to zero or hold at near its current value?
If not check out the FPR.
Check the FPR with a hand vac, draw a vac on it see if it holds. If not replace it.
If it holds a vac then use anything suitable to pinch off the return line down stream of the FPR (rubber section) and test the fuel pressure agian.
A pair of vise grips, a small c clamp whatever you have handy will work. Pinch off the return line (only do so for a very short time, dead heading a good pump can/will damage it). If fuel pressure value consistently rises substantially with return line clamped off? replace the FPR.
#18
09-20-2012, 06:25 PM
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Sorry, yes. Held 32psi for several minutes before I depressed the release.
Never thought of manually closing the return line, I'll try that before the swap.
On another note after deleting the mass of smog equipment and plugging off any unnecessary ports I now have a CEL. It might be the piece on the drivers side of the 90* intake elbow. It has red black and white vacuum lines. Any ideas what this is or does? Can it be tricked to eliminate the CEL?
Never thought of manually closing the return line, I'll try that before the swap.
On another note after deleting the mass of smog equipment and plugging off any unnecessary ports I now have a CEL. It might be the piece on the drivers side of the 90* intake elbow. It has red black and white vacuum lines. Any ideas what this is or does? Can it be tricked to eliminate the CEL?
#19
09-24-2012, 09:38 PM
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Got the pumps swapped, had to swap pigtails to. My front tank was FULL of varnish and had'nt work in some time so I did it 1st. The donor had a fairly new tank so with the bed off we got the entire tank and pump swapped only pulling the pump to chase the wires since 90'/96' are different color codes. Turned pump on and watched through the filler hose hole. Everything worked good so we took it for a bed-less ride. Full throttle, full power, full-on peg leg burnout LOL!
Got to the back pump and just swapped pumps, upon re-instaal found a kinked line. Trying to straighten line it cracked, crap! Going to get high PSI rubber fuel line and fix it hillbilly style ( I can hear you objections now LOL).
Now to find out why I have no O/D and fix.
Got to the back pump and just swapped pumps, upon re-instaal found a kinked line. Trying to straighten line it cracked, crap! Going to get high PSI rubber fuel line and fix it hillbilly style ( I can hear you objections now LOL).
Now to find out why I have no O/D and fix.
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