I have a 91 Mercedes and no idea what is going on HELP!

Asked by Jun 24, 2014 at 02:44 PM about the 1991 Mercedes-Benz 300-Class 4 Dr 300TE 4MATIC AWD Wagon

Question type: Maintenance & Repair

I have  a 91 Mercedes 300te 4matic. and has been running amazingly till recently and when it gets heated up the RPMs drop and wont go over about 5Miles I have no idea on what else to try I replaced the fuel filter and have ran injector cleaner threw it. the problem started after I replaced the top radiator hose and only occurs when its heated up

10 Answers

70,165

If it only doe,s it when it,s hot,check plug,s and wire,s if that dos,nt help check coil,s.

70,165

All so may check fuel pressure,could be stopped up fuel filter or fuel pump going bad.

I replaced the coil wire and spark wires and it still did the same thing the plugs seem to be okay, and the only coil i'm aware of got replaced in the last year... I'm not going to lie I don't know a whole lot about cars i'm a girl but I was wondering if it could have something to do with the idle control valve or the fuel pressure regulator but like I said I don't know much about cars

70,165

I think it may be your fuel pump,go have the fuel pressure checked it will tell you this,but from your post,i am thinking bad fuel pump,91 model,have you ever had oneput one in it>?

I haven't but I've only had it for about 4 years when I did the fuel filter it was the original one the car was made with. so I guess it wouldn't hurt to try to fuel pump

70,165

Fuel pump,s act crazy when they are going bad,no problem half the time then poof,setting side the road

70,165

Go have fuel pressure check to know this before you spend your money to prove it,but i think that is your problem, Good luck with it gurl : )

Thank you!!! I'll probably post on here again if that doesn't help any

Have a 1990 Mercedes 300sel. Got to where having shut the warmed up engine off, Go in store and 10 minutes later car would not start. If you wait 20 minutes would start like nothing ever happened. Replaced the fuel accumulator next to fuel filter and that solved the problem. The old one stopped keeping pressure up to the fuel injection and allowed fuel vapor to form. Gas boils around 160 degrees F. Also when you shut off the engine the warm temp will rise on the engine a little.

I have found when changing any part that is somehow going through the onboard computer, after putting a new part in, reset the computer by taking the NEG off the battery post for at least and hour. Then hook it back up.

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