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Matt, Engineer
Category: Mercedes
Satisfied Customers: 21858
Experience:  Mechanical Engineer with 23 years experience in the auto industry, 8 yrs in formula 1 engine testing
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560sel I have a 91 560sel. It idles a little low around 500

Customer Question

I have a 91 560sel.
It idles a little low around 500 -600.
But the real problem is that when you press the gas and and call for strong power, the engine stalls.
If you gently accelerate the car is fine. And it moves along the highway with plenty of power as long as you don't call for sharp acceleration. If you do, it dies.
ideas. I thing the fuel pump is ok
Submitted: 11 months ago.
Category: Mercedes
Expert:  Matt replied 11 months ago.


I'd 1st remove the rubber intake boot from the fuel distributor and then unscrew on the top of the unit find the central nut , pipe feed into the fuel distributor and push down on the aluminum plate under the rubber boot you should see the main fuel metering pin / needle rise up smoothly as you push down the plate, if its sticky or dirty then its possible this is getting stuck.

If this is OK then remove all the injectors but leave them connected to their fuel lines and put all into a clear container then turn the ignition on and (having replaced the central feed pipe nut) lift up the aluminum plate all the injectors should spray at once and look for ones that aren't spraying as much as the others - and replace or ultrasonically clean as required

its also worth checking for any vacuum leaks after the fuel distributor

The best way to locate a leak is to have the engine running and warm and then spray lighter gas /propane or even brake cleaner around each joint in turn. If the engine rev's up you've found your leak.

Now you might think that spraying lighter gas around a hot engine isn’t wise, however the flash /ignition point of gas is about 400°C so you need a naked flame or spark to set it off and I’ve used this method for many years without incident.

Work your way through each possible joint one at a time and you should find it. I use a slightly flattened piece of brake pipe and some rubber hose from the can of lighter gas to provide a spraying 'wand' and allow a direct blast of gas into each area, especially those difficult to reach with large implements.

Customer: replied 11 months ago.

thanks, ***** ***** try theses things and revert


Expert:  Matt replied 11 months ago.


just get to me on this post