Fuel Pump Not Turning On
Thread Starter
Instructor
Joined: Nov 2007
Posts: 138
Likes: 0
From: Richwood NJ
Fuel Pump Not Turning On
Hi again, still trying to diagnose my fuel delivery problem. I have no fuel pressure at the fuel rail (checking the Schrader valve). Swapped the fuel pump relay with horn relay, swapped the fuse with the horn fuse, still no fuel. Most of the time I can't hear the fuel pump turn on. However, I did here it once. It sounded as if it was trying to turn on and off and on again (if that makes any sense).
Anyway, I'm suspicious of a bad ground, as the car had sat outside for quite a long time
But I'm curious what the best method of diagnosing this problem is? Should I run a wire directly to the fuel pump from the battery and test if the pump runs? Or will a bad ground still keep it from running? How about checking the voltage at the pump?
Has anyone else had a problem like this that turned out NOT to be a bad fuel pump. I've read just about every post I can find on "crank but not fire" and I'm really hoping this is something that can easily be fixed. NOTE: fuel pump exhibited no problems prior to this. Went out one day and the car just wouldn't start.
Thanks again for all your help!
Anyway, I'm suspicious of a bad ground, as the car had sat outside for quite a long time
But I'm curious what the best method of diagnosing this problem is? Should I run a wire directly to the fuel pump from the battery and test if the pump runs? Or will a bad ground still keep it from running? How about checking the voltage at the pump?Has anyone else had a problem like this that turned out NOT to be a bad fuel pump. I've read just about every post I can find on "crank but not fire" and I'm really hoping this is something that can easily be fixed. NOTE: fuel pump exhibited no problems prior to this. Went out one day and the car just wouldn't start.
Thanks again for all your help!
Thread Starter
Instructor
Joined: Nov 2007
Posts: 138
Likes: 0
From: Richwood NJ
Well, I did here it turn on once since all this started. Prior, I had no trouble with fuel delivery. No stumbling or stalling, car ran perfectly fine. I'd also like to rule out any other cause before spending the time and money on the pump, only to have it not be the problem. I've read a few other posts where people have been in my same position, replaced the pump, and still had no luck.
Safety Car
Joined: Aug 2000
Posts: 4,933
Likes: 30
From: San Rafael CA
If you've read other posts you should realize that the first and best thing to do is to display the DTC data stored in the cars computers. Often the computers will tell you what the problem is.
Go here if you don't know how to do this ...
https://www.corvetteforum.com/techti...D=26&TopicID=1
Be sure to post the ENTIRE code (such as P1234H) and list them all.
Go here if you don't know how to do this ...
https://www.corvetteforum.com/techti...D=26&TopicID=1
Be sure to post the ENTIRE code (such as P1234H) and list them all.
Le Mans Master
Joined: Jul 2002
Posts: 7,370
Likes: 8
From: Slave to the evil empire
Cruise-In V Veteran
St. Jude Donor '04
To make the pump run continuously pull the fuel pump relay out and then jumper across it and the pump will run, there is no need to run a wire back to the fuel pump. If you jumper across the contacts on the relay and the pump doesn't run then disconnect the connector at the pump and check to see if you have 12 volts, if you have 12 volts check to make sure your also getting a good ground at that connector.
Obviously if you have power and ground but the pump doesn't run, then it's time for a new pump.
BTW - what year car are we talking about, is this with the FFS fuel system?
Thread Starter
Instructor
Joined: Nov 2007
Posts: 138
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From: Richwood NJ
It's a '99, stock fuel system. I checked the DTC but have "no codes" for all the modules. I'll tried running a jumped to the relay pin from the battery terminal, though I was a little short on supplies...... I had to improvise using jumper cables and a paper clip! Probably not the best connection, and I'm not even sure it was conducting! In any event, the fuel pump did not run.
Safety Car
Joined: Aug 2000
Posts: 4,933
Likes: 30
From: San Rafael CA
Le Mans Master
Joined: Jul 2002
Posts: 7,370
Likes: 8
From: Slave to the evil empire
Cruise-In V Veteran
St. Jude Donor '04
It's a '99, stock fuel system. I checked the DTC but have "no codes" for all the modules. I'll tried running a jumped to the relay pin from the battery terminal, though I was a little short on supplies...... I had to improvise using jumper cables and a paper clip! Probably not the best connection, and I'm not even sure it was conducting! In any event, the fuel pump did not run.
Remove the relay and then look at the slots that the relay fit into, (you'll see the wiring schematic printed on the side of the relay), take a paperclip, piece of wire or whatever and carefully (without damaging the pins) insert it into the 1 slot that will connect the 12 volts going into the relay with the the other slot going out to the fuel pump, there should be no need for jumper cables
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Thread Starter
Instructor
Joined: Nov 2007
Posts: 138
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From: Richwood NJ
Haha, okay, I'll give that a shot. I found another post where someone just ran +12v from the battery to that terminal. I only used the jumper cables cause I had nothing else.... but this makes a lot more sense! Just bypass the relay all together. This should make the fuel pump turn on regardless of whether or not the key is on right?
Thread Starter
Instructor
Joined: Nov 2007
Posts: 138
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From: Richwood NJ
I'm gearing up to go out and check out the car. It's not at my home so I have to get all the necessary equipment prepared, most importantly, information! I want to hook a multimeter up to the pump to make sure I'm getting voltage when I turn the key on. Where exactly would I find the terminals connecting to the in-tank fuel pump?
Le Mans Master
Joined: Jul 2002
Posts: 7,370
Likes: 8
From: Slave to the evil empire
Cruise-In V Veteran
St. Jude Donor '04
Right at the pump itself, remove the left rear tire and you'll see a steel panel covering the tank, remove that panel and then you'll see the pump and the connector.
Thread Starter
Instructor
Joined: Nov 2007
Posts: 138
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From: Richwood NJ
Okay, so I checked voltage at the fuel pump and I do indeed have voltage when I turn the key to ON. The spike in voltage is also accompanied by a noticeable clicking sound which I assume is the pump trying to turn on. I think it's safe to say i need a new pump, so... What are my options here? I've read that it's better to go with an after market brand rather than an OEM for both price and performance. Any suggestions?
Thread Starter
Instructor
Joined: Nov 2007
Posts: 138
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From: Richwood NJ
I wish it were that easy. This happened like 20 miles after filling up a full tank! Best $60 I ever spent.... Anyway, I'm pretty sure it's the pump, since I was able to read 12v at the pump when I turned the key. I'm looking into getting a Lingenfelter LPE High Flow Fuel Pump. No because I need the added performance, but simply because it's $270.00 cheaper than the OEM one. Should I get it, or will running this on a stock car cause trouble? Thanks!
Safety Car
Joined: Aug 2000
Posts: 4,933
Likes: 30
From: San Rafael CA
Buy on-line
You should be able to get the OEM fuel pump much cheaper on-line ....
try ....
http://www.gmpartsdirect.com
and
http://www.gmpartshouse.com
For a 1999 the left fuel pump/sender should be part #89047745, GM list price is $572.00
try ....
http://www.gmpartsdirect.com
and
http://www.gmpartshouse.com
For a 1999 the left fuel pump/sender should be part #89047745, GM list price is $572.00
Le Mans Master
Joined: Jul 2002
Posts: 7,370
Likes: 8
From: Slave to the evil empire
Cruise-In V Veteran
St. Jude Donor '04
I wish it were that easy. This happened like 20 miles after filling up a full tank! Best $60 I ever spent.... Anyway, I'm pretty sure it's the pump, since I was able to read 12v at the pump when I turned the key. I'm looking into getting a Lingenfelter LPE High Flow Fuel Pump. No because I need the added performance, but simply because it's $270.00 cheaper than the OEM one. Should I get it, or will running this on a stock car cause trouble? Thanks!
Tech Contributor
Joined: Dec 2006
Posts: 10,962
Likes: 29
From: Van Buren Arkansas
Wounded Warrior Escort '11
I wish it were that easy. This happened like 20 miles after filling up a full tank! Best $60 I ever spent.... Anyway, I'm pretty sure it's the pump, since I was able to read 12v at the pump when I turned the key. I'm looking into getting a Lingenfelter LPE High Flow Fuel Pump. No because I need the added performance, but simply because it's $270.00 cheaper than the OEM one. Should I get it, or will running this on a stock car cause trouble? Thanks!