bubble bubble, toil and trouble! Tech help needed
 

Recently the 87 300E has developed a strange sound. On warm days, after the car has been run a while and then parked for 10-20 minutes, restarting the car produces a bubbling/boiling liquid sound the from the right rear (fuel pump area). The sound is sometimes loud and continuous, sometimes less noticable, and sometimes not even there at all. Once in a while it is accompanied by a rough idle. It usually goes away in 5-10 seconds. Rarely it has a short harmonica 'hmmm' sound afterwards for the first couple of accelerations. The car runs well, but has always been a little ragged at idle.

I have speculated on anything from a bad gas cap seal to a failing diaphragm in the accumulator, but don't want to throw parts at it until it goes away. Anyone encounter this situation before? BTW, the 2 mufflers and pipes have been replaced recently, but that didn't change the symptoms.

Thanks for any suggestions.

I wonder if failing fuel pumps would make that sound...

Hi Paul:
From what I gathered, the fuel pumps make a growling sound when failing. Could a fuel pump or pump relay fail in a way to cause these problems? It isn't an issue after the first couple of minutes, or starting the car when it is cold. Just when restarting within 1/2 hour of driving, mostly on warm days. Strange.

TTT.

Any ideas?

TTT

No ideas from anyone? The location makes me think fuel pumps/accumulator, but I am not anxious to pitch money in the wrong area!

What happens when you remove the gas cap?

I don't have any answers on this one, but I'm interested in the "hmmm" sound coming from the rear end - every once in awhile I'll get a (loud) whine from mine, but it hasn't occured often enough for me to be able to show it to a tech.

-anthony

John

A friend had a BMW 325i that did similar things. He went through fuel pumps, filters, etc. Finally, the shop foreman opened the fuel tank and discovered several silver round pieces at the bottom of the tank. It seemed that someone would pour in fuel additives and ignore the seal at the top of the bottle.

They fished out the pieces and all the symptoms disappeared. They speculated that the pieces would float around and cause the inlet to get covered enough to make the pump work overtime and to occasionally cause rough running, other times, nothing.

Keep us posted,

Haasman

ouch!
 

Ignore the silver covers on fuel treatement bottles? that's plain stupidity and carelessness

anyway, my car used to make a bubbling noise from the fuel tank, I check by lending the trunk an ear (190E) but it went away, I think it might have something to do that I was using a wrong fule tank cap, I got the right one now he he :)

the origianl, and I mean ORIGINAL, was so badly beaten that my car would leak fuel, so as a quick fix I got a oil cap that amazingly fit :)

waiting for it to occur again.

xp

I thought it could be the fuel cap, but it was replaced with a new MB cap at the last smog inspection a year ago, so I ruled it out. However, it is cheap enough that I will get a new one and see if that makes it go away. If it does turn out to be the cap, then either MB quality has dropped for the cap to last less than a year, or more likely, the leapord urine that is sold as EPA approved gasoline in southern California did a job on the seal!!!