PaxPeter

1. car wouldn't start
2. thought it was the fuel pump and replaced it, fuel relay works fine
3. problem happened again, disconnecting battery seemed to help for a bit
4. now won't run for long after disconnecting the battery

any other things I should check? alternator/battery/starter are all new.

THANKS FOR ANY FEEDBACK OF WHAT I SHOULD TRY NEXT!!

RPB

Check the CPS, MAF, TPS and the condition of the engine harness which from the factory was biodegradable on these. GL!

PaxPeter

thanks so much, I'll check all those.

fortunately 1995 was the last model year with the biodegradable wiring ... that's part of the reason I got a 1996!

PaxPeter

AHH, one more update on this, so when trying to start it, it's not actually getting any fuel pressure.

It has a new fuel filter, new fuel pump, the pressure is fine is you jump the pump - it's just not getting the signal to power the pump (or something like that) when starting.

Any other suggestions based on this?

thanks you!

oldsinner111

maybe ignition switch,possible k38 relay

Wyverne

in some places the amount of ethanol in the gasoline reduces the octane rate of the gasoline so much, the gasoline would not burn if you threw a match on a puddle of it.
try and find a fuel station that is not part of a discount chain, that does not operate a huge number of discount gasoline stations.

PaxPeter

starter does actually turn so it isn't the lock out switch, it's also not the alarm, it's also not the ethanol.

When turning the key, the started turns great but there's no fuel pressure.

Whatever tell the fuel pump to turn on when starting isn't doing it.
(fuel pump and filter are new, when powering the pump relay, the fuel pump does go on).

Wyverne

When I first got my car, it had been sitting in a garage for three years, it has been a mechanics dream, troubleshooting the car from one end to the other, fixing this, fixing that, trying to get parts or something fixed every day,
one of the things that I had never seen before was a similar type problem that was fuel related, the ethanol had actually separated from the gasoline, I put in a siphon hose, and drained out the "fuel", in putting it into a five gallon glass jar, it looked like layered Jello, water at the bottom, the ethanol, then the gasoline, replaced the fuel pumps, and the rear high pressure fuel line, then put in a few gallons of fresh gasoline from a reputable source, and it started up, the next problem was with the location of the ignition coils, over behind the left headlight, what were those people thinking?
The engine had a really weak spark going to some of the plugs, in checking that there was no wires that were grounding out near the spark plugs themselves, I carefully took out the ignition coil wires, taking photographs as the process went along so as to be able to put them back properly, there were leaves, dirt and accumulated unknown stuff in many places along the path of the wire, I took the wires off, put some gasoline on the a washcloth, and cleaned them as best I could, mine is a 1992, and the plastic sleeve the coil wires was in literally crumbled in my hands as I was taking them out, I went to a local junkyard and found a car that had a very similar sized orange protective plastic slipover coverings, and put them over the coil wires, I cleaned the ignition coils, and thoroughly cleaned the dirt and accumulation from the area where the coils are, the new fancy wire covers look pretty neat,
There is that old saying that a clean car runs better, it is true, the Mercedes cars are susceptible to a lot of problems caused by dirt and water, I am working on cleaning out all the debris and dirt from under the hood of my car, these are some very entertaining machines and amazingly easy to work on and repair.

PaxPeter

under my hood is pretty spotless.

It'll go to the dealer today, I'll post what the problem was when I find out but I'd welcome more suggestions if anyone has any!

oldsinner111

I read at benzworld.org forum where a man jumped pins on his MAF to power pump,perhaps you could try that forum

PaxPeter

SOLVED!!

It was the crankshaft position sensor. Although we had replaced it, the NEW one was an aftermarket unit that also seemed to have a problem.

Wyverne

phew! had me worried.