Fuel pump rattles
Thread Starter
Burning Brakes
Joined: Apr 2003
Posts: 783
Likes: 2
From: Wake Forest, NC
St. Jude Donor '05
Fuel pump rattles
I pulled a fuel pump out of my 84 yesterday.
Supposedly, it was a brand new stock (GM) pump.
It was intermittently losing pressure. It would drop to 0 pounds, the motor woud quit, and you could still hear the pump running for a couple seconds.
Anyway, when I pulled it, I noticed that if you gently shook the pump from front to back, it would rattle - like something inside it was loose. is that normal??? The new pump I put in it didn't do that.
Supposedly, it was a brand new stock (GM) pump.
It was intermittently losing pressure. It would drop to 0 pounds, the motor woud quit, and you could still hear the pump running for a couple seconds.
Anyway, when I pulled it, I noticed that if you gently shook the pump from front to back, it would rattle - like something inside it was loose. is that normal??? The new pump I put in it didn't do that.
Le Mans Master
Joined: Dec 2004
Posts: 5,789
Likes: 8
From: Myrtle Beach SC
St. Jude Donor '05-'06
What your hearing I believe is the resonator that sits in fron of the pump. They are not supposed to rattle and that is a sign that it is bad and could have been one of the reason for loss of fuel pressure. It is there to smooth out the pulses of fuel to a smooth flow on stock gm pumps. Some people by pass them with a piece of hose without much trouble.
Thread Starter
Burning Brakes
Joined: Apr 2003
Posts: 783
Likes: 2
From: Wake Forest, NC
St. Jude Donor '05
Thanks for the reply.
Is the resonator actually IN the pump? Your not talking about something that mounts outside of the pump, right? I don't remember anything mounted in front of the pump when I had it out, but just checking.
I'm talking about the pump itself, just holding it in your hand and it rattling when you shake it back and forth.
I'm not arguing with you, just curious. If this is something thats in the pump, how would someone bypass it with a hose?
I'm tempted to take the pump apart and see for myself whats rattling as it's destined to be thrown out anyway. But, the one thing holding me back, I PAID a dealer to install this pump. Took it back to them when they were supposed to warratny their work and they said the pump was fine and the ECM was bad.... Thats when I said don't do anything else, I'm coming to get my car. I hooked up a fuel pressure gauge to a T at the filter and measured pressure to troubleshoot the problem. Determined it had to be the pump and replaced it (84) with an 85 fuel pump. Constant pressure went up 2 lbs (held back by the regulator) when running and it's been doing fine ever since.
I'm tempted to take the pump back to the dealer, although I know they won't do anything about it...
Thats the only reason I haven't torn it apart so far.
Is the resonator actually IN the pump? Your not talking about something that mounts outside of the pump, right? I don't remember anything mounted in front of the pump when I had it out, but just checking.
I'm talking about the pump itself, just holding it in your hand and it rattling when you shake it back and forth.
I'm not arguing with you, just curious. If this is something thats in the pump, how would someone bypass it with a hose?
I'm tempted to take the pump apart and see for myself whats rattling as it's destined to be thrown out anyway. But, the one thing holding me back, I PAID a dealer to install this pump. Took it back to them when they were supposed to warratny their work and they said the pump was fine and the ECM was bad.... Thats when I said don't do anything else, I'm coming to get my car. I hooked up a fuel pressure gauge to a T at the filter and measured pressure to troubleshoot the problem. Determined it had to be the pump and replaced it (84) with an 85 fuel pump. Constant pressure went up 2 lbs (held back by the regulator) when running and it's been doing fine ever since.
I'm tempted to take the pump back to the dealer, although I know they won't do anything about it...
Thats the only reason I haven't torn it apart so far.
