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Fuel Pump Failure? by BZAnathema
Started on: 02-25-2014 12:04 AM
Replies: 3 (104 views)
Last post by: johnguzman1212 on 02-25-2014 07:06 PM
BZAnathema
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Report this Post02-25-2014 12:04 AM Click Here to See the Profile for BZAnathemaClick Here to Email BZAnathemaSend a Private Message to BZAnathemaEdit/Delete MessageReply w/QuoteDirect Link to This Post
So I think my fuel pump is going out, but I also have a leak somewhere in the fuel system (I think I have an injector malfunctioning/stuck open and running too rich). I've had trouble with the car dying on acceleration, intermittent power at times, difficulty starting, etc. but only when the fuel is already low. So since I don't know what a Fiero does when the fuel pump starts to die, I'm asking if any of you guys can speak to the specific symptoms I should look for to know if my pump is bad or if I'm just getting terrible mileage because of leaks and rich injection. Thanks!
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notaguru
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Report this Post02-25-2014 06:54 PM Click Here to See the Profile for notaguruClick Here to visit notaguru's HomePageClick Here to Email notaguruSend a Private Message to notaguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
Auto Zone (and some other shops) will *LEND* you a competent fuel pressure tester. The one from AZ screws directly onto the tap on the pass side of the engine without adapters, though it's hard to reach. The hose is normally long enough to reach the window, but the driver can't see it so it takes two people - one twisted around.

I've been told that normal pressure is 36-45psi.

If pressure is LOW, you should check the voltage AT THE PUMP TERMINALS. If it's below battery voltage, then you need wiring to get the power to the pump. If that voltage is at least 12V with engine running, then your problem could be:
1. Bad pump, but when you go to all that trouble to get it out of the tank, inspect the wiring. In fact, you can test the pump with the tank dropped - just put it into gasoline and apply voltage. Use a rubber hose to get the result back into the tank - make it a loop. Varying voltage (engine OFF, then ON) will tell you if the pump is responsive to power.
2. Clogged sock (the initial screen in the fuel tank, at the bottom of the pump/sender assembly).
3. Clogged fuel filter. It will take only so much crap before impeding fuel flow and reducing fuel pressure.
4. Crimped/damaged fuel line. The wrong rock under the car will do it.
5. Bad injectors or bad O2Sensor. Remember, the ECU will command fuel until the O2Sensor says the ratio of gases in the exhaust is correct. If the O2Sensor is lying, the ECU could command excess fuel from the injectors. Most problems here will trigger a code, but not all...
6. Crap in tank (the old CIT syndrome). Enough junk and the car simply won't run correctly, and the ECU will sometimes try to throw gas at the problem. Solution is to drop the tank, clean it out (use a cig lighter to check for internal dirt), blow out all lines, replace filter, etc. Maybe not a cigarette lighter... even a flashlight should be turned ON some distance from the tank.
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Csjag
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Report this Post02-25-2014 07:05 PM Click Here to See the Profile for CsjagClick Here to Email CsjagSend a Private Message to CsjagEdit/Delete MessageReply w/QuoteDirect Link to This Post
I have dropped the tanks on my 85 duke and 85 Gt and I took them to a local radiator shop where they cleaned and sealed them and put in a drain all for $100.
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johnguzman1212
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Report this Post02-25-2014 07:06 PM Click Here to See the Profile for johnguzman1212Click Here to Email johnguzman1212Send a Private Message to johnguzman1212Edit/Delete MessageReply w/QuoteDirect Link to This Post
I own a 87 fiero when I did my conversion I removed the fuel tank . when I did I noticed that the small hose that connects the pump to the assembly had a hole in it so when the tank got low the pump just pumped gas back into the tank and not the fuel line this explained why my car would die during low fuel times. check that hose I used a small fuel line hose to fix it of the same id. btw its a lot of work to drop the tank good luck
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