Fuel Pump Issue
Thread Starter
Racer
Joined: Jan 2007
Posts: 322
Likes: 0
From: Chapin South Carolina
Fuel Pump Issue
I searched the forums and really couldn't find an issue like mine.
About 3 months ago my fuel pump went bad. It was pumping only about 10psi accroding to my mechanic. The pump was only a year and half old but I got it off ebay and conceded that it was probably trash. So my Mechanic replaced it with a new AC Delco unit.
Since then I purchase a new truck and was breaking it in and so I only drove my vette for probably 15 days in 3 months. Then last wednesday I noticed in the morning that I was losing acceleration at times. But that afternoon for lunch and when I went home it was fine. The next morning I leave to go to work and get about a quarter of a mile from the house and the car just dies on me, like it is out of gas.
Now it has been cold and I have not had a chance to look at it but I plan to look at it this weekend. Could I have another bad fuel pump? Or is there something else to look at?
About 3 months ago my fuel pump went bad. It was pumping only about 10psi accroding to my mechanic. The pump was only a year and half old but I got it off ebay and conceded that it was probably trash. So my Mechanic replaced it with a new AC Delco unit.
Since then I purchase a new truck and was breaking it in and so I only drove my vette for probably 15 days in 3 months. Then last wednesday I noticed in the morning that I was losing acceleration at times. But that afternoon for lunch and when I went home it was fine. The next morning I leave to go to work and get about a quarter of a mile from the house and the car just dies on me, like it is out of gas.
Now it has been cold and I have not had a chance to look at it but I plan to look at it this weekend. Could I have another bad fuel pump? Or is there something else to look at?
Le Mans Master
Joined: Jul 2007
Posts: 5,043
Likes: 8
From: Tampa Florida
I searched the forums and really couldn't find an issue like mine.
About 3 months ago my fuel pump went bad. It was pumping only about 10psi accroding to my mechanic. The pump was only a year and half old but I got it off ebay and conceded that it was probably trash. So my Mechanic replaced it with a new AC Delco unit.
Since then I purchase a new truck and was breaking it in and so I only drove my vette for probably 15 days in 3 months. Then last wednesday I noticed in the morning that I was losing acceleration at times. But that afternoon for lunch and when I went home it was fine. The next morning I leave to go to work and get about a quarter of a mile from the house and the car just dies on me, like it is out of gas.
Now it has been cold and I have not had a chance to look at it but I plan to look at it this weekend. Could I have another bad fuel pump? Or is there something else to look at?
About 3 months ago my fuel pump went bad. It was pumping only about 10psi accroding to my mechanic. The pump was only a year and half old but I got it off ebay and conceded that it was probably trash. So my Mechanic replaced it with a new AC Delco unit.
Since then I purchase a new truck and was breaking it in and so I only drove my vette for probably 15 days in 3 months. Then last wednesday I noticed in the morning that I was losing acceleration at times. But that afternoon for lunch and when I went home it was fine. The next morning I leave to go to work and get about a quarter of a mile from the house and the car just dies on me, like it is out of gas.
Now it has been cold and I have not had a chance to look at it but I plan to look at it this weekend. Could I have another bad fuel pump? Or is there something else to look at?
Team Owner
Joined: Jan 2003
Posts: 20,315
Likes: 245
From: Summerland B.C. Canada
Get a fuel pressure gauge and check the pressure at the fuel rail to see what it is doing. There are several components in the fuel system that might cause a low pressure situation. Clogged fuel filter, ruptured or leaking pulsator module(right above the fuel pump in the tank) or a busted fuel pressure regulator (FPR) diaphram.
http://members.shaw.ca/corvette86/Fu...mDiagnosis.pdf
Thread Starter
Racer
Joined: Jan 2007
Posts: 322
Likes: 0
From: Chapin South Carolina
Sorry for the late reply. Lots of Rain and cold weather kept me off of it. But things have warmed up, so I am back on it. I checked the electrical to the fuel pump and that seems to be working. I am getting zero on the fuel pressure on the rail. I tried disconnecting the fuel line hoses at the fuel pump to see if it would pump and it does not pump. Is this a bad fuel pump again?
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
I'd remove the pump and connect 12v to it to see if it comes on. I'd hesitate playing with voltage around the fuel tank.
If it does I'd first check the wiring and the relay.
Jake
West Point ROCKS!
If it does I'd first check the wiring and the relay.
Jake
West Point ROCKS!
Team Owner
Joined: Jan 2003
Posts: 20,315
Likes: 245
From: Summerland B.C. Canada
It takes less than 10 minutes to pull it and test it. Did you have 12 volts back there ??
If you apply battery voltage to terminal "G" on the ALDL connector, you will be sending 12 volts to the pump until you remove the jumper wire. This comes in handy when checking the pump electrical circuit and pump operation.
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
It takes less than 10 minutes to pull it and test it. Did you have 12 volts back there ??
If you apply battery voltage to terminal "G" on the ALDL connector, you will be sending 12 volts to the pump until you remove the jumper wire. This comes in handy when checking the pump electrical circuit and pump operation.
Just another example of old age setting in. LOL
Jake
West Point ROCKS!
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Thread Starter
Racer
Joined: Jan 2007
Posts: 322
Likes: 0
From: Chapin South Carolina
Thanks. I will try that tomorrow if it does not rain. 
I am getting 9.35v at the connector just before the fuel pump but I could have a low battery at this point from all the cranking. But I would think 9.35v would be enough to get some type of pressure out of it. If it is a fuel pump, is there a good reason to blow 2 in 2 years or just bad luck.
Thanks for everything
I am getting 9.35v at the connector just before the fuel pump but I could have a low battery at this point from all the cranking. But I would think 9.35v would be enough to get some type of pressure out of it. If it is a fuel pump, is there a good reason to blow 2 in 2 years or just bad luck.
Thanks for everything
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
If you ground terminal 'G' on the ALDL, you by-pass the fuel pump relay and the oil pressure switch.
I don't know, specifically how low battery voltage would effect your voltage reading at the pump but if your battery voltage is low it probably would cause a low reading at the pump.
How about connecting a battery charger to the battery and then check the voltage at the fuel pump.
Jake
West Point ROCKS!
Jake
I don't know, specifically how low battery voltage would effect your voltage reading at the pump but if your battery voltage is low it probably would cause a low reading at the pump.
How about connecting a battery charger to the battery and then check the voltage at the fuel pump.
Jake
West Point ROCKS!
Jake
Last edited by JAKE; Mar 12, 2009 at 11:57 AM.
Advanced
Joined: Jun 2008
Posts: 63
Likes: 1
From: Pittsburgh PA
The typical operating range for GM is 9-16v. 9v is the lower operating range becuase voltage can drop down during cranking, or when high load devices are turned on (headlights, a/c, etc.)
If you are at 9.35 volts now, it's going to drop when cracking. However, the fuel pump is on for a few seconds as soon as you turn on the key, right? So the pressure should be fine prior to cranking.
If you are at 9.35 volts now, it's going to drop when cracking. However, the fuel pump is on for a few seconds as soon as you turn on the key, right? So the pressure should be fine prior to cranking.
Le Mans Master
Joined: Mar 2004
Posts: 8,700
Likes: 298
From: Ft. Lauderdale Fl