Bad fuel pump? (Page 1/1)
Josh86gt DEC 06, 09:01 PM
I was taking my fiero out for a small joyride earlier today and as soon as I pulled into my driveway (thank God) the engine died on me and would not restart after a little bit of testing I sent 12 volts to the fuel pump terminal on the OBD1 port and got absolutely nothing even with the Schrader valve on the fuel rail removed nothing was happening is this a bad fuel pump or could there be something else causing this?
Patrick DEC 07, 01:32 AM

quote
Originally posted by Josh86gt:

...is this a bad fuel pump or could there be something else causing this?



Empty gas tank. No, I'm not kidding. This happens more frequently than you might think.

Can you at least hear the fuel pump "hum" when power is applied?
Josh86gt DEC 07, 01:34 AM

quote
Originally posted by Patrick:

Empty gas tank. No, I'm not kidding. This happens more frequently than you might think.

Can you at least hear the fuel pump "hum" when power is applied?



I did a little more testing after posting this I hooked 12 volts to the G terminal on the OBD1 plug and got absolutely nothing even when I removed the Schrader valve on the fuel rail I hear no hum and my gas tank was showing about 5/8
Patrick DEC 07, 01:42 AM

Where was the 12v from... the cigarette lighter? (The reason why I ask, is that 12v from a source other than your installed battery would also need to be grounded to the car.)

As long as the harness from the gas tank is still connected, then 12v to the fuel pump terminal of the ALDL port should run the pump.
Josh86gt DEC 07, 01:43 AM

quote
Originally posted by Patrick:


Where was the 12v from... the cigarette lighter? (The reason why I ask, is that 12v from a source other than your installed battery would also need to be grounded to the car.)

As long as the harness from the gas tank is still connected, then 12v to the fuel pump terminal of the ALDL port should run the pump.




I ran the 12v from the positive terminal on my battery

Patrick DEC 07, 02:09 AM

Well, as long as 12.5v or so was being supplied to the fuel pump terminal (and your grounds are all good), then the pump should run.
Dennis LaGrua DEC 07, 04:33 PM
On a 40 yr old vehicle with the original fuel pump chances are that it has outlived its useful service life and is most likely bad. The tank must be drained, removed and the pump replaced. Its not a hard job but the car must be elevated high enough to disconnect everything and drop the empty tank. If you do this insure no sparks, hot lights or flames anywhere close.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

Patrick DEC 07, 05:33 PM

quote
Originally posted by Dennis LaGrua:

If you do this insure no sparks, hot lights or flames anywhere close.



And be damn careful that the car is safely supported!
Dennis LaGrua DEC 07, 11:07 PM

quote
Originally posted by Patrick:

And be damn careful that the car is safely supported!


Thanks for adding that.

------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

Patrick DEC 07, 11:36 PM

quote
Originally posted by Dennis LaGrua:

Thanks for adding that.



Yeah... I feel bad every time I think of that excited new PFF member a few years ago that got crushed under his Fiero. <sigh>