1990 300SEL hard start when warm

[alabbasi]

All

I bought a 1990 300SEL. The car was a non runner and the PO put a used FD in it in hope that it would fix the problem. It did not and he sold it to me. I was not sure what was wrong, I got it started but it spluttered and spat and then died.

I decided take the old fuel distributor and soak it in my 5 gallon jug of berrymans for a couple of days and then re-install it as the piston was locked up. While it soaked, I put new plugs in.

The car took a couple of cranks to start but then fired up. I adjusted the fuel mixture by ear until the car sounded right and let it idle.

It appears that once the car warmed up, the engine died and i could not restart. I tried to add a little fuel into the intake and it tried to start but spat fire out of the intake.

Any thoughts here?

I plan on putting some more fresh gas as I have to wonder if bad gas is causing the problem. My only other thoughts are that the timing may be way out.

[Grumpy560W126]

Al, Have you tried disconnecting power from the EHA valve. I don't know much about the 300 6 bangers but I know on my 560 when I had this trouble, disconnecting all engine sensors and the EHA valve helped me pinpoint the problem. Though there are many areas to look at, I think that maybe a faulty ECU unit or a bad ground somewhere could be it for you. backfire through the air metering plate is not good and that should not have happened, have you checked the compression? how long did the car sit without being driven? drain the old gas out and change the filter if you have one handy. what about correct FP at the FD?

[alabbasi]

Thanks! I have not gotten that deep into it as it's been crazy busy. At first, I thought it may have done something horrible like jump time but the way it ran today for the first 10 minutes or so makes me think otherwise because it was silky smooth.

I will or may get deeper into it if the coil does not work. Apart from the engine, this is a spitting image of my 560SEL so I can always part it. It has many usable parts. It would be a crying shame because it's a quite clean.

I will disconnect the EHA valve and the computer in order to see what's going on.

[mlozzi200478]

i totally agree with the above user,def check into the e.h.a. system. try disconnecting the 2 pin connecter its located on the back of the fuel distributor,its a large black sensor with 2 screws in it, it bolts directly to the back of it,facing firewall.mines having a very similiar issue,mine wont start on cold mornings unless its plugged in ,but then it will not get out of its own way that is untill i dissconect the eha,its wierd.they generally last forever,untill they crack open and begin weeping fuel down the back of the motor,i guess thats why most of them cost approx $280.00.give it a shot,goodluck hope it works.

[mbdoc]

Of course check the cap & rotor.

Timing is not adjustable.

[alabbasi]

Thanks guys. I replaced the coil, the car started and I adjusted the mixture again (I messed with it before). I got it humming like a sewing machine until it got warm and then nothing. I pulled the coil wire from the distributor and saw no spark. I suspect that there is something going on when the car gets hot with the ignition system. David Poole indicated that it could be the 4 pin temp sensor on the back of the intake, if not that, then the EZL or the crank position sensor.

I bought a temp sensor and plugged it in (without bolting it to the block) but no luck. So i'm off to the junk yard for an EZL.

[gidpor]

how did you solve the issue ? was it indeed the ezl ?

[alabbasi]

It turned out to be the distributor cap which was the problem.

[gidpor]

thanks. good luck