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Discussion Starter #1
I know that there are a few threads on this topic but most center around the fuel pumps. In my case both fuel pumps, fuel filter and connecting lines have been replaced by a qualified shop. as well as a general going over of all mechinicals. The issue is that after some driving, 15 minutes or so the fuel pump (not in-tank) begins to make an intermittent loud groaning noise. with longer drives the groan becomes constant. I notice the noise when stopped. not sure if its happens while driving due to general engine sound of driving. I replaced the barometric sensor, the one in the side panel behind passenger seat. the part was pulled from a spider, not new. my guess is that the groan must have something to do with the rather complicated vacuum system. regardless of the groaning noise the car runs great. one concern is that the fuel pump me be getting damaged, or possible other elements in the fuel system. once, when low on fuel, the fuel pump made the same groaning noise. seemed at that time the fuel pump was starved for fuel. after a fill up, no noise. the whole thing is rather frustrating.
 

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But Mad North-Northwest
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Try cracking the gas cap. If the groaning goes away then it's something in the vapor recovery system, if not it's something else.

If it's the vapor recovery system, it has two check valves in it that can plug up, you should verify both of them flow air in the correct direction.
 

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If its happening only when the tank is, say, below 1/2 full, then it could be the rubber hose connector on the in-tank pump is cracked and sucking air. They're quite prone to that, as I've read many times here. That can lead to main pump noises and failure. These connectors don't come packaged with new pumps, so it could be that the mechanic just reused the old one when replacing the in-tank pump. But the sound you describe does indeed sound like the main fuel pump - I know that sound well! You can confirm by looking under the rocker panel when the car is running and you'll hear it clearly.
 

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a groaning main fuel pump is usually the in tank pump (supply pump) not 'supplying' properly....and yes it will damage the main pump eventually.

the fact that you say after a fill up it doesn't groan again for a while, makes me think you have a vacuum in the tank and by filling up you have released that.

as tom says either crack open the gas cap after a drive and see if air shoots out or gets sucked in (a little vacuum is OK)
alternatively, drive around a while with the gas cap screwed on loosly and see if the groan is there.

ask the shop who did the in tank pump whether they replaced the short 'stepped hose' that joins the pump and gauge sender together, or at least can verify it was good when they did the work.
 

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Easiest fix to a starving or groaning pump is to double check when the first out of tank filter was changed. If the gas tank is dirty it wo
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n't take long for the filter to clog and the result is a staving groaning pump. If you have this kind of filter and suspect it is dirty, open it up with a hack saw and you will confirm your suspicions. The photos don't show the crud inside the canister
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002.JPG
 

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But Mad North-Northwest
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I don't believe an '82 will have that filter. There should be a coarse filter sock on the in-tank pump, and then the large Bosch can filter downstream of the main pump.
 

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Discussion Starter #8
Thanks Guys, some real good knowledge. Tried the tank fill up. Still groans. I went to try the gas cap release. Unless its me, I sure felt like there was some air flow that seemed to be sucking into the tank. When I closed it, the noise was no longer intermittent. It seemed steady, all be it still what might seem louder than normal. It's my understanding the fuel pump has a continuous low level electronic noise when all things are normal. I now just rounding owning the spider for a year, a lot of situations that are new to me. As I've mentioned the shop that did the work was a qualty garage that specializes in Italian vintage cars. so, got to believe that knew what they were doing. Any suggestions on how to trouble shot the vacuum system?
 

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Discussion Starter #9
update... tried a few suggestions. gas cap to release possible pressure. don't believe its the exhaust heating the fuel, since its groans at start up. getting more confused. the noise used to start after about fifteen minutes. now starts groans when it starts. the vacuum system lines are extensive, so maybe that the issue. frustrating for sure.
 

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Pull the fuel line before the main pump, put the line in a jar and jump 12V to the in tank pump and see if it is pumping. You will see if it is doing its job. If no fuel or very little suspect pump or fuel line obstruction. If good suspect main pump. Then run a line out of main pump into jar and repeat. If low volume pump is probably seen its days. If good pull line off fuel rail repeat, etcetera, etcetera, etcetera...
 

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I'm going to have to beg off on this one. '82 is getting into territory I have NO experience with and there were loots of idiosyncrasies with swapping out tanks and filters etc.etc.
 

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It sounds like you may just have a defective main fuel pump. There are many different manufacturers of these pumps, and it could be that the new one installed was either a 'cheapo' or just plain defective. I'd try taking the pump out and bench testing it, albeit very briefly, as you don't want to run these very long without fuel. I did that with my new one when it arrived, and it made no 'groaning' on the bench, and works fine.
 

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Actually narrowing this problem is pretty straight forward and most likely a simple fix. The board is always here to help but I do understand if you dont feel comfortable doing it!
 

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Discussion Starter #14
Actually narrowing this problem is pretty straight forward and most likely a simple fix. The board is always here to help but I do understand if you dont feel comfortable doing it!
Actually narrowing this problem is pretty straight forward and most likely a simple fix. The board is always here to help but I do understand if you dont feel comfortable doing it!
Well, this one has got me. Here is where I am, new parts... in tank fuel pump, fuel filter, fuel pump hose, main fuel pump, fuel pump mounts... I just put in a new Bosch main fuel pump, installed today. thought that was going to do the job. still making groaning noise. Not sure how to check current, but gave it a try. Volt meter gave a reading of 11.52 at the tank pump wires. 10.46 at the main pump.
 

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Dont just throw parts at it, do things methodically.
 

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Another thought - you mentioned replacing the fuel pump mounts. There is typically a rubber tube that wraps around the main pump that fits between the pump and the mount. The pump has an inherent low-volume hum when it runs. Perhaps if there is not a rubber buffer that 'hum' becomes a groan as the vibration travels through the metal, even though the pump is healthy? Just a thought......
 

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Discussion Starter #18
Thanks again for the help! so things are getting more puzzling. I saw a post about the inertia sensor being a potential problem. Looks like prior owner disabled it. Joined the two wires to complete the circuit. So the one time the fuel pump didn't groan since this began was when I went for a drive for about 80 miles. the temperature was mid 30"s. Went for a test drive this morning for about 20 minutes or so. Enough to warm things up. No groan, temperature was mid 30's. I know May 9th in Maryland. Go figure. What could cold temperature do to create a starved fuel situation for the pump. Could it be something with the fuel injection. It has been a bit hard starting lately. Does not just turn over like you would expect from fuel injection.
 

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You've lost me now. I thought cold temps. resulted in a quiet pump? Yet you say cold temps create a 'starved fuel' situation......
 
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