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-   -   W123 280E- Won't Run Hot (http://www.peachparts.com/shopforum/vintage-mercedes-forum/259139-w123-280e-wont-run-hot.html)

Tony 12 08-16-2009 01:24 AM

W123 280E- Won't Run Hot
 
Hi all.
I haven't been around for a while, but now getting back into my cars and I need help.
My Australian 1979 W123 280E starts and runs ok cold, but once it warms up, it misfires under load, then stalls and won't restart.
If you can get it to restart, you need to hold the accelerator wide open to keep it running.
I'm out in the country and don't have access to pressure guages, but I do have another running '79 280E that I can take parts from.
So far I have replaced warm up regulator, fuel distributor, cold start valve, ignition coil, distributor, spark plugs and leads. And yet the problem persists.
Can anyone offer any advice what to try next, please?
Many thanks in advance.
Tony.

JimFreeh 08-16-2009 08:24 AM

Just a guess, but if you can run when cold, then the enrichening circuit is working, and your car is leaning out when the cold start shuts down.

Verify by looking at exhaust and see if it is blowing black smoke. If it's clean, your leaning out too much, if it's black it's getting too much fuel.

Given what you've swapped so far, might be low fuel pressure...

Jim

Tony 12 08-16-2009 06:13 PM

Thanks so much for the input, Jim.
Are you suggesting I try the pump or is there some other item that may affect fuel pressure?
Actually, the pump is easy to do, so I might just do that anyway. :)

ctaylor738 08-16-2009 09:24 PM

And the accumulator, and change the filter.

Tony 12 08-16-2009 09:33 PM

Thanks Chuck
I actually discounted the filter as it looks very new.
From the outside............... ;)
Will give it a shot.
Thanks again gentlemen

Tony 12 09-12-2009 10:55 PM

Well............... you guys may not believe this................. :?
I decided to spend the day sorting this problem and it is now fixed.
The one thing I failed to mention was that when changing ignition distributors, I broke the rotor off the donor car, so used the original. That turned out to be critical.
However, (and this is the weird bit) after changing the rotor the car still wouldn't start. Fiddling this morning, I touched the air flap with the ignition on and noticed that I heard the fuel pump relay but not the pump. :?:
Turns out that the relacement pump off the donor car decided to stop working at the same time as I put the new rotor in. :shock:
So, back in with the original pump and all is right with the world again.
I'm confident now that it was just the rotor all along, but because it gave the sensation of running rich, I had spark, I had replaced 99.9% of the ignition components and the running problem occured every time the temperature gauge hit 87 degrees, I assumed it was fuel related.
Thanks to all for taking the time to offer suggestions.


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