W126 sel 420 1987 114k

[T. Ketterson Sr]

The motor keeps dieing as if starving for fuel durning a normal trip round town. The fuel relay and fuel filter have been replaced less than a 500 miles ago. The repair shop used a "iro" Mercedes Fuel Pump relay PN 003 645 2505. Which I have found out to be a sorry replacement. If I put my foot on the gas it will crank right up, however, at the next stop or slow to turn bam... the motor dies. The motor is turning over great, but unless I give it some gas no start. One other thing if I keep my foot lightly on the gas I can keep it from dieing. Help... T. Ketterson Sr

[86560SEL]

I had a 1985 380SE that would occasionally stall when I would turn at a low speed or stop. I was told it could be the idle control valve, but I took it to a Mercedes shop and he said it was leaking injector seals. I sold it before I installed new ones, so not sure if that was the definite problem or not. They do not leak gas from what I understand, but rather suck in air.

[wbain5280]

Given the age and mileage, I too would suspect vacuum leaks and the idle control valve. That valve is controlled by the small relay looking processor behind the false front on the passenger side in the middle.

You would do well to get the large rubber hoses that run under the fuel distributor, the hoses supplying air at the injectors, vacuum elbows and quite possibly the vacuum switches on the water channel at the front of the intale manifold. Also include the injector seals and holders and the rubber seals between the intake manifold halves.

The EGR pipe that runs from the valve to the intale manifold would also need to be cleaned.

You can tale the intake manifold off as well for a more complete cleaning. Take a lot of pictures and make a drawing of all the bolt locations and their length and positions.

While it sould like a large and complex job, it's really not that hard if you approach it step by step and document what you have done.

The only problem I had when I did my 420SEL was positioning the EGR pipe for removal and installation of the manifold.

[Carson357]

Originally Posted by wbain5280

Given the age and mileage, I too would suspect vacuum leaks and the idle control valve. That valve is controlled by the small relay looking processor behind the false front on the passenger side in the middle.

You would do well to get the large rubber hoses that run under the fuel distributor, the hoses supplying air at the injectors, vacuum elbows and quite possibly the vacuum switches on the water channel at the front of the intale manifold. Also include the injector seals and holders and the rubber seals between the intake manifold halves.

The EGR pipe that runs from the valve to the intale manifold would also need to be cleaned.

You can tale the intake manifold off as well for a more complete cleaning. Take a lot of pictures and make a drawing of all the bolt locations and their length and positions.

While it sould like a large and complex job, it's really not that hard if you approach it step by step and document what you have done.

The only problem I had when I did my 420SEL was positioning the EGR pipe for removal and installation of the manifold.

on the 1987 the idle control is under the passenger footwell area, looks like a fuelpump ot klima relay

[86560SEL]

I wonder why this seems to be more of an issue on the V8 W126 Mercedes and not the I6 W126 models. I rarely hear of the 6-cylinders with this issue, or do they?

Originally Posted by wbain5280

Given the age and mileage, I too would suspect vacuum leaks and the idle control valve. That valve is controlled by the small relay looking processor behind the false front on the passenger side in the middle.

You would do well to get the large rubber hoses that run under the fuel distributor, the hoses supplying air at the injectors, vacuum elbows and quite possibly the vacuum switches on the water channel at the front of the intale manifold. Also include the injector seals and holders and the rubber seals between the intake manifold halves.

The EGR pipe that runs from the valve to the intale manifold would also need to be cleaned.

You can tale the intake manifold off as well for a more complete cleaning. Take a lot of pictures and make a drawing of all the bolt locations and their length and positions.

While it sould like a large and complex job, it's really not that hard if you approach it step by step and document what you have done.

The only problem I had when I did my 420SEL was positioning the EGR pipe for removal and installation of the manifold.