Today my ‘94 E420 died a few times and finally wouldn’t restart. I jumped across the fuel pump relay and manually ran the pump. Afterwards the engine started strongly but began to stumble under load barely making it home. I am not sure whether to replace the fuel filter, pump relay? Or LH module…. The engine did run so I think the signal is getting to the relay. I did NOT notice any clicking sound from the relay... Where should I begin checking?
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Fuel starvation
- Thread starter Phoenix127
- Start date
Update: I replaced both fuel pumps and fuel filter and this stalling problem has been resolved. Still getting an intermittent miss after warm up and thinking this is separate ignition related. Possibly the infamous insulators. Will see.
Insulators are clean dry and in perfect condition. It appears so have a distributor cap issue. One has orange colored insulators on a black cap and one is all black. The all black cap has what appears to be tracks or small cracks from the center post out to two of the edge terminals. Arcing would explain my miss under acceleration. Is Bosch or Beru the way to go? I think Bosch is the original which looks in much better shape. Who has the best price?
I assume you pulled the insulators and checked the back side for liquid, correct? Not just the front side that's visible with the cap removed?
Does the miss go away after 20-30 minutes of driving, or is it persistent ? If it goes away when warmed up, try adding the vent slots as discussed in the other thread.
For new caps, people have reported problems with all brands, so it's a crapshoot. Beru caps may be NLA now leaving Bosch as your only option. Add the vent slots to new ones prior to installing. I'd consider new rotors at the same time, OE only now that the old stock of Beru-reboxed-OE has mostly sold out (or, is priced as high as discount OE).
Does the miss go away after 20-30 minutes of driving, or is it persistent ? If it goes away when warmed up, try adding the vent slots as discussed in the other thread.
For new caps, people have reported problems with all brands, so it's a crapshoot. Beru caps may be NLA now leaving Bosch as your only option. Add the vent slots to new ones prior to installing. I'd consider new rotors at the same time, OE only now that the old stock of Beru-reboxed-OE has mostly sold out (or, is priced as high as discount OE).
Thank you for the information and advice. Both sides of the insulator were pristine. Both camshaft oil seals were dry. The only moisture residue seemed to be inside the caps. There were also traces appearing almost like pencil marks or cracks inside the Beru cap from the center post to two of the outer terminals. I tried to clean this up using paper towel and electrical contact cleaner. Also tried to clean the terminals of some green oxidation using steel wool. This didn’t do much I am afraid as on the test drive the engine missed even more than before. Previously the engine ran well until warm and began intermittently missing. This worsened under load. Sometimes it would disappear after 10-15 minutes. But lately the miss has become more prevalent. I parked it and have new Bosch caps and rotors now on order.
I replaced this cap (purchased 10,000 miles ago) and it’s rotor with new Bosch parts. The engine runs much better now. I was suprized by the inside of the cap having the cracks or marks I guess from the high voltage inside.
Attachments
I’ll have to look up the post with the directions for drilling those. I was short on time.
FYI - Essential M119 Ignition "Tune Up" mods [Distributor cap vent / slot] | M119 Engine
Hi all, I have been meaning to address this on my little used 500E for years.... it is a problem I myself recognised about 5 years ago when I first looked at an m119 distributer cap..... Compare to any other distributor cap of the era such as an m104 and you will see there are NO ventilation...
www.500eboard.co
Courtesy of our departed, resident ignition scientist, @robm.UK
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