Hi,

My '92 300E is stalling every once in a while. Mostly when I accelerate and the RPMs are starting to get up to 3000. It feels like somebody just cut out the fuel. I just replaced my fuel filter and my mechanic said that it's most likely the primary fuel pump, it's noisy and draws too much current. Anybody have these problems? I just don't want to spend a bunch of money on the fuel pump if that doesn't fix it. I appreciate any help.
Thanks

 

Is the fuel pump noisy to YOUR ear? I'd hate to think the mechanic just wants to throw parts at the problem hoping it'll fix the car without first doing a proper diagnosis.

Maybe the converter ceramic has broken up. This'll restrict exhaust and reduce high-end performance. Give it a kick and see if it's rattling.

 

My 1990 300E 4 Matic runs for about 45 minutes then shuts off, the first diagnose was the electronic ignition control unit. Has anyone had any similar problem... I didn't replace that yet. Just the fuel pump relay, and it still shuts off. Any input much appreciated.

 

I had that problem before and it could be one of the three things below.

1. Fuel Relay
2. Injection
3. Fuel pump

Had all three problems, different times of course.

 

I think it could also be the idle control valve. If your idle is fluctuating and then the car shuts off, this could very well be the problem (at least it was for me).

 

If it is the idle control valve... where is it located on a 1990 300E 4matic and do you replace it or just make an adjustment. Any feedback much appreciated.

Thanks,
deblaze

 

Idle control valve is located under the air filter housing. You just take it off and you can see the idle control valve (its a shape of a "t") and has some rubber hoses connected to it which may be cracked and should be replaced if they are. The idle control valve itself should be replaced, at least thats what I did. Its very easy to do, just take out the air filter housing and disconnect the hoses and wires connected to the idle control valve and put the new one in and attach the hoses and wires.

 

from my experience, your fuel pump is nearing its end, so IMO, you should replace your fuel pump (even if its not the primary cause) because when it happens then youll be having a bigger problem if its far from any repair shops

 

Here is a better description of what is happening. The car stalls only when I accelerate. When I am at a light and try to accelerate slowly, the car is fine, but if I give it some gas and start getting into 3000+ rpm the car stalls. I can restart and keep going. It's been really bad this hot arizona summer, but as the weather cooled the problem seemed to go away. But today it came back, I barely made it home. Anything above 2000 rpm will stall the engine. And if I can feel it stalling and let go of the gas immidiately, sometimes it chokes a bit but doesn't stall. Is it the fuel pumps or bigger problems?

Thanks

 

was the problem there BEFORE you changed the fuel filter or did it start after? Got the filter hooked up in the correct direct?

 

The problem was there before the filter was replaced. I didn't change the filter, my mechanic did. He is the one who said that fuel pump is to blame.

 

I have a 1990 300 E that is doing the exact things you have described. I however read to the end of the thread and never saw how or if the problem was solved. Please advise on how or what was done to fix the problem.

 

Hello Guys, after 2-3 weeks of trial and error and $1,500. we tracked the lost of fuel to a gas tank that was full of rust and corrosion. There is a small filter that looks like a sieve at the bottom of the gas tank. This seive over time collects very small particles and debris. When the car is at idle the demand for gas is not very high and enough gas seeps through the filler at the bottom of the gas tank. However, if you start to drive around and increase the RPM/load on the fuel pump this filter quickly (5-10 min) gets filled and clogged and the engine dies for lack of gas. When this happens and the fuel pressure drops off the debris and dirt kind of fall off like the way nails would fall of a magnet that lost it magnetic force. With the filter now temporarily cleared enough gas will past through so that on restart motor will restart. But as soon as you put some pressure and increase the RPM (after another 5-10 minutes) the process starts to repeat itself.

The big problem with this behavior is that it fits MANY, MANY, MANY, MANY, MANY, MANY, other symptoms and owners having similar problems may not find this to be the cause of their problem.

We changed the tank and the car has been running perfectly since then.

If anyone wants to eliminate this promblem from their list of possible causes the best and easiest thing to do is to (with the car off and the battery disconnected) disconnect the main gas line that pulls gas from the tank to the pump. When this line is disconnected gas should be pouring down in torrents, (providing there is gas in the tank). If you do this and gas is merely dripping drop by drop or may be a little faster (but not to the extent that you have gas pouring out like a tap fully turned on) then the flow of gas from the tank to the pump is very ristricted and like me you may have a tank that is filled with rust or some other entity blocking the flow.

If this is not your cause good luck with your diagnosis.