ok there is sometimes a long whining from the pump after i shut down and lately, when coming to a stopsign the engine seems like its loosing fuel pressure. it will do this up and down rpm thing going from 800 to 450 to 800 ect. like the fuel pres is oscilating.
however, just today it started to do this (what I think is) pressure loss thing when I was accelerating. not a bog but a loss of power - like 40% or so - then full power.
Is this really my fuel pump or could it be the relay or maybe something else entirely???
I know how hard it is to replace but I am prepared seeing as how the cristmas winfall is coming our way soon (well those of us who have nice relatives at least).
gimmie your opinions and I thank you in advance.
(edit) ok duh -- my title - should there be any codes that let you know if your fuel pump is on its way out? I have always had an intermittent code 54(like once every few months) but it hasnt come up in over 6 months.
James

------------------
88 WS6 T/A 305 TPI--
K&N,Air foil,hypertech chip, thermostat+fanswitch
no MAF screens, no cat, dynomax exh, urethane motor+trans mounts,
SSM frame con, Bilsteins
homemade ramair.

[This message has been edited by 88305tpiT/A (edited December 08, 2000).]

 

88,

Two completely separate issues. The fuel pump run-on after engine shutdown is because the fuel pump get power supplied by the relay AND through the auxilliary oil pressure switch. As long as there is 7 PSIG oil pressure in the galleries, the pump will operate. It would reasonably happen for a longer period in cooler weather since the oil should be a little more viscous, not dropping pressure past bearings as quickly. Fuel pumps also tend to make a bit more noise when cold, so you would likely notice it a bit more.

If you suspect the pump is not achieving adequate pressure, test the pressure at the fuel rail. It should be at 37 PSIG +/- 3PSIG at idle with the vacuum hose connected to the regulator.

My guess is that there is a problem somewhere else. Fuel pressure typically doesn;t oscillate in a failure, it just falls off. You might want to check ignition, filters, and IAC operation. Set the TPS voltage and base timing. Make sure the MAT and CTS sensors are correct. Check for error codes, since some codes won't necessarily set the MIL lamp.

------------------
Later,
Vader
------------------
"No matter how hard you try you can't stop us now"
Adobe Acrobat Reader 4.0

 

also check your Fuel pressure regulator. Just to eliminate the possibility, go to Advanced Auto (parts america) and pick up a fuel pressure regulator kit.

Just my 2cents, it solved my FP problem before.

------------------
92 Formula
305 TPI 5speed
1LE package
Mods: SLP headers,SLP catback,SLP air foil,ported plenum,K&N, Crane AFPR (47psi),MSD6AL, MSD wires, AC DELCO cap/rotor/plugs, Bosch O2sensor, 3:73s,JET fan switch, Macewen white face gauges, Intellitronix Digital Gauges

 

Ok update

the whining noise was a leak in the gas tank that stopped when I unscrewed the cap. this is good news I dont have to repl. fuel pump.
but how bad is it to have such a small leak that it takes like 3-5 min to stop reliving pressure. Im guessing not too bad.

anyway I plan to get an accel 300+ ignition and wires and I think that might solve the problem with the hesitation and idol. Ive had the same splitfire wires for like 50K now and I think theyre due. plus Ive been having electrical problems for awhile now with some jury rigged stuff the previous owner did so I think the igition will clear that up.

THanks for youre help guys
I appriciate it.

James

------------------
88 WS6 T/A 305 TPI--
K&N,Air foil,hypertech chip, thermostat+fanswitch
free mods, dynomax exh, urethane motor+trans mounts,
SSM frame con, Bilsteins
very trick homemade ramair.

 

For the hesitation problem. Replace your cap,rotor,plugs,wires. If it still exists replace the ignition module in the base of your distributor cap. Thats what caused my problem similar to yours. This may sound strange, but check where your cigarette lighter plugs in. Make sure no pennies or metal objects (even gum wrapper) is lodged in there. You'd be amazed how that affects your car!

When you say it takes 3-5min to relieve pressure do you mean 3-5 seconds?

------------------
92 Formula
305 TPI 5speed
1LE package
Mods: SLP headers,SLP catback,SLP air foil,ported plenum,K&N, Crane AFPR (47psi),MSD6AL, MSD wires, AC DELCO cap/rotor/plugs, Bosch O2sensor, 3:73s,JET fan switch, Macewen white face gauges, Intellitronix Digital Gauges

 

88,

Any leak in the fuel tank is not good. Instead of replacing the tank, you might want to try some of the external tank repair compounds. If it doesn't work, you've really lost very little. If it works, you're back in business.

------------------
Later,
Vader
------------------
"No matter how hard you try you can't stop us now"
Adobe Acrobat Reader 4.0

 

Formula.
no when I say 3-5 i mean Minutes!
this leak is from a very small hole ( I can actually hear the fumes escaping at about an octave higher tone than the fuel pump)

if you want to know what my ignition has been doing lateley look at this other post I did {Tach wire -- engine cuts out. HELP!
} its in the general engineboard. BTW my cap, rotor look fine and I replaced my module when I had the tach problem mentioned on the other post. you may want to read this for the horror story inside though - its kinda funny what my car did to me.
I think the wires are due though - I just found one that wasnt all the way on again today and I think the boot is shot
well there goes another 250 to the make my car go faster fund.
Vader - I think finding the leak may be easier said than done. if I actually do find it I will go ahead and plug it but otherwise I can live with it until it causes a giant fireball that kills me and takes out a bus full of nuns as I hit the gas to fly by.
truthfully I only found this leak today but I will get it looked at ASAP.
Thanks again for the diagnosis help.
James