my 1971 220d starts to cut out at 50 - PeachParts Mercedes-Benz Forum

tobacco jack · #1 03-02-2011, 10:43 AM

hi, my 220d runs fine round town but when you get out on the main roads at about 50 it seems to misfire, possibly on one cylinder. theres no smoke and backing the throttle off cures the problem untill you accelerate again.it will also do this at lower speed when going up a steep hill in kickdown.ive tried resetting the throttle rods and ive replaced the lift pump and some of the dodgy fuel pipes, but its still there. sometimes it goes away and i get it up to 70 and it starts to surge on and off as if its trying to clear its throat.i put a fuel injector cleaner in and no real difference.its driving me nuts any ideas?

kerry · #2 03-02-2011, 10:49 AM

No mention of new fuel filters. Have you swapped them out? Same with air filter.

tobacco jack · #3 03-02-2011, 11:47 AM

hi yes i have replaced the fuel filter and washed out the oil bath cleaner i n meths and re oiled it.

t walgamuth · #4 03-02-2011, 12:57 PM

There are two filters to change. Also a good idea to treat tank to biocide to kill off any bacteria which may be multiplying there.

kerry · #5 03-02-2011, 01:06 PM

You could try running it off a jug of fuel in the engine compartment to see if the problem goes away. If so, there's a blockage upstream. You could also switch the feed and return lines in the engine compartment. If the problem goes away, it's probably a clogged tank screen.

tobacco jack · #6 03-03-2011, 05:45 AM

hi where is the second filter? ive changed the big one at the front of the engine but i cant see another one thanks.

t walgamuth · #7 03-03-2011, 06:19 AM

It should be between the hard line which comes from the tank and the injection pump. It will be a small normal looking plastic bodied filter like the ones used on older engines with mechanical fuel pumps.

layback40 · #8 03-03-2011, 07:46 AM

There should also be a strainer in the tank. Was there a lot of black stuff in the filter you changed? it sounds like bugs in the fuel. There are products you can get to add to the fuel to fix it. Startron is one that comes to mind. Probably best that you change your fuel supplier as well.

t walgamuth · #9 03-03-2011, 07:59 AM

to elaborate on what layback40 stated....fuel will grow bacteria if there is water in the fuel.

This can be from rain or condensation and both those sources can be from your fuel supplier or could be introduced directly into your tank. If you have a car that has been setting it will be more of a problem.

A car that is driven regularly and suddenly has bacteria most likely got it from the fuel supplier.

layback40 · #10 03-03-2011, 08:36 AM

Quote:

Originally Posted by t walgamuth

to elaborate on what layback40 stated....fuel will grow bacteria if there is water in the fuel.

This can be from rain or condensation and both those sources can be from your fuel supplier or could be introduced directly into your tank. If you have a car that has been setting it will be more of a problem.

A car that is driven regularly and suddenly has bacteria most likely got it from the fuel supplier.

Thanks Tom !!

QUOTE ive tried resetting the throttle rods and ive replaced the lift pump and some of the dodgy fuel pipes END QUOTE

It sounds to me like the car does not have a primary filter. The lift pump has been replaced but no filter seen.

psaboic · #11 03-03-2011, 05:22 PM

As someone who went through this EXACT same issue just last week, here is what I suggest. Change the fuel filters again (my issue was caused by a bad spin on fuel filter I had bought and used for only about a week)!

If the filters do not fix it, try this in order

1. Clean the filter screen in the fuel tank
2. Blow (or flush) out the lines between the tank and the injection pump
3. Check all fuel line connections for leaks and look for air bubbles in any lines (both static and with the engine running)
4. Adjust the valves

This should set you up right. Please let us know how it goes

rscurtis · #12 03-03-2011, 05:27 PM

Does this car by chance still use a pneumatic governor?

tobacco jack · #13 03-05-2011, 03:59 PM

will try that filter screen. i think the fuel is ok i use it for my van and mazda diesel and no problems there.however i can see a small weep from the supposedly new lift pump which under load could be pulling in air as there are tiny bubbles in the line from it after attempting any kind of speed.thanks for advice guys.

t walgamuth · #14 03-05-2011, 05:38 PM

The biocide will kill any bacteria and make it flow through the strainer normally and you won't have to remove the strainer. Removing the strainer sounds simple but you have the fuel to deal with from the tank.

tobacco jack · #15 03-06-2011, 01:01 PM

yes it does have a pneumatic governor. are they bother

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