240 DL sedan 1989 150K miles

I have realized that my newly installed fuel pre-pump is loud.

Recently I replaced the sender/hose/pre-pump/sock assembly. All went well.
All this was replaced with new parts I bought from fcpgroton.com (I think VDO).

I have noticed that the pre-pump is relatively loud. By that I mean that I can actually hear the buzz from sitting in the driver's seat with the car running, doors closed, radio off. It can also be similarly heard when openeing the trunk (sedan). I did cover the cap in the trunk and siliconed to seal.

BTW the buzz is not the main pump. If I pull the pre-pump fuse it goes away, car still runs (as normal). The main pump is original I think and dead quiet.

So how loud is this pre-pump supposed to be?
Are there maybe quality issues with the replacement?

Another question that just came to mind: I assumed that the polarity of the wire connection (ground and +12V) to the pump was fixed (DC pump). The wires actually only went one way since they had a plastic sleeve on them... The replacement pump looked identical to the original one in every respect. Was I correct to assume that there was no chance of mixing the polarity (+ to - and - to +) when connecting it? makes sense....

Any other ideas why this is loud, or maybe should it be? It is absolutely not to any annoying level, just wondering if hearing it from inside the car was normal. BTW it has maintained the same volume from the moment I put it in 1K miles ago. All appears to work great.

Thanks in advance,
Greg Mustang

Greg,

I put in the same pump from FCPGroton, a Scantech pump.

I have the same noise, I can hear it from driver's seat.

I also changed the fuel filter during in-tank pump change.

Perhaps it's just the way it is.

Cheers,

Also have an 89 sedan and installed the same pump. Can't say I can hear it in the car.

The only thing I can think off is maybe a dirty fuel filter? Did you replace yours?

Good idea... actually I have the replacement and will do that soon...

Maybe it even has something to do with the height of the pump (i.e .if the sock touches the bottom or not). The height adjustment is not very obvious, though I tried to get it where the original one was. I'm thinking that if the sock touches the bottom it would likely dampen and slightly quiet it down.

Thanks,
Greg

Greg, I agree with the possibility there is contact with the tank bottom. Even with the sock material squashed between the inlet and the tank, the contact would make it loud.

I bought the little hose -- might have been the same place you did -- just to see if it was an ordinary piece of fuel line (it was) and found it to be too long as supplied. Mine don't make noise (but my hearing is suspect).

Also, I don't agree with the idea that they burn out from lack of fuel to cool them. This mode suits the main pressure pump, but not this little light duty transfer pump. The electronics keep it from running unless the car is running (fuel present) anyway. Sure it needs fuel to lube the bushings, but you'd have to do a heck of a lot of cranking on fumes to keep that from happening.

If for some reason it was wired (or built) backward, I believe you'd have a hard time getting fuel out of a tank less than 1/2 full. Even harder than with the pump disconnected.

--
Art Benstein near Baltimore

Thanks Art. Agreed about the non-possibility of miswiring...

Any ideas about the buzz? Should i just forget about it?

Greg

Forget about it? I wouldn't. But another brickster's better half would say I have a serious psychological flaw in that regard.

Did you trim the hose so the pipe butted with the pump outlet? Dunno whether that would be good, as in keeping the bottom from contacting through the sock, or bad, as in conducting some sound through the steel outlet tubing. Maybe just shy of butting...

Would I rig the pump with my remote starter cable and crawl under the tank to feel, push on the tank and listen? If it was nice out.

Curiosity gets the better of me. Did you get a VDO with a yellow molded plastic housing - mounting bracket molded in, or was it an AC Delco in a metal housing?

There are some things we just have to get to the bottom of, so to speak. Or near to the bottom.
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Art Benstein near Baltimore

The pump looked identical to the original, if I recall it was metal. I had to re-use the bracket from the original to mount ir to the sending unit clamp.

I did cut the small hose (which was WAY too long, and BTW a regular fuel hose). I tried to make the overall assembly equal to the original in length, so that the sock is in the same depth as before. BTW my original accordian hose was intact, should I have re-used it?

Whatever, it really doesn;t bother me that much, I guess if I feel lucky again to not have the tank explode in my face I might undo it and take another peak.

Thanks Art,
keep up the curiosity, it keeps us going.

ciao,
Greg

1989 240 sedan B230F 150K miles
1992 940 GLE B234F 16v 50K miles

A foreign car professional mechanic I know told me he once put in nine ACD in-tank pumps on a 240 in rapid succession for a customer who wanted a quiet one. The first eight were noisy.
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Thanks to everyone for the help, Doug C. 81 242 Brick On Blocks, stock; 86 240, 129K

All I can say is my pump was changed by a shop(before I started working on my car myself), dont know if it was maim or prepump. But it sounds as LOUD as yours. Mechanic said it burnt up from letting the gas run too low, it uses the gas to cool the pump. Hope this helps, Breadman

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Breadman '83 244GL 220K

Thanks.

From what I know, the main pump 'burns up' and gets louder when the pre-pump is not working... this is actually why i changed my pre-pump, to 'renew' it to avoid having to replace the main pump ($$$).

Before all was quiet.

Now I hear the pre-pump.

Oh well, at least I know they both run properly.

The radio goes on louder now!

Thanks,
Greg