1986 230e Hot Start Problem
 

Help ! I have a 1986 230E injection with a really annoying hot start problem.It starts from cold first time every time,but once it has warmed up it takes three or four attempts of long cranking before it starts.When it does start it is usually on 2-3 clinders for a split second and accompanied by that sweet weak/lean petrol smell.
This problem is getting worse.I have owned the car about two and a half years and it has been brilliant.Its a manual gearbox model and is really economical and really flies for a big car.Performance and economy have not been affected by this problem.
I have changed the fuel filter and all the other service requirements are up to date.
I am a qualified mechanical engineer with 20 years+ experience
with vehicles and plant.:confused:

hot start problem
 

Were from Scotland and my wife has the same problem with her 1991 230e. Weve tried changing the fuel valve regulator, cleaning the petrol with additive with no luck.

I put an earlier post in regarding this problem and was advised to check the Overvolt Protection Relay which is behind the battery.

I couldn't distinguish what was what in there so left welll alone. I believe the ovp is about £70 so it would be an expensive experiment if this wasn't the cause.

Please let me know if you get yours fixed.

Generally, the OVP affects hot starting only, and once started, starts up fine (i.e. not sputtering, fuel smell, etc).

Any dash indicator lights on as the problem worsened (ABS maybe)? That would point to the OVP. SO would rough idling, but that may be just a blown fuse on top of the OVP.

The fuel smell has me leaning towards the fuel pressure regulator.

Although if the OVP is original, it is due for a replacement as the original is defective for the hard starting symptoms...

Had a similar problem with the jag last year, admittedly a little more failure prone than the Benz but still this may help:

Is there a non-return valve in the fuel system (I assume so)? If this leaks, all the fuel could be vaporizing back to the tank on a hot start, the starting system would tend to prime the line more on a cold start, masking this problem. Anyway, this was replaced and it helped quite a bit.

The ultimate solution, found after the head gasket leaked and needed replacement, was to unstick one of the fuel injectors. The car was sometimes starting on only 5 cylinders (XJ6 uses a straight 6 for those not familiar with the model), again the starting system was better at compensating for this when the engine was cold. Continued use of fuel injector cleaner and fuel system cleaner (I use STP for the FI cleaner and Valvoline for the fuel system cleaner) have kept the problem at bay for months now, even in the hot Oklahoma summer. So for a cheap way to start, try a couple fuel tankfulls of fuel system cleaner, see if that doesn't clear up the injectors a bit and help those hot starts.

The hot start problem on my 1989 230E was solved after replacing the fuel injector nozzles. The old onew were leaking, causing a pressure drop in a fuel line and a rich air/fuel mixture. If
I remember correctly the nozzles were $20 each. The day when I replaced the nozzles I also changed the spark plugs so the spark plugs may have been contributing to the problem too. Try listening to the fuel pumps also. Sometimes the fuel pump relay gets bad and engages after 2-3 attempts to start.
Currently my car has a stalling in traffic problem. Once stuck in traffic I had to wait for 1-2 hours for the car to start back. Then last week I opened the hood and tapped on the fuel pressure regulator with a back of a screwdriver. The car started right up and so far I did this 2 times when the car stalled and the tapping trick works. The solution to my problem is buying a new fuel pressure regulator. I am trying to get it cheap and looking for a used one now. Good luck on finding the solution to your hot start problem.

Hurshi

I was trying to cure the hot start problem on my 230E and I thought it was the injectors. I changed them with no change. My fuel pump went out last year and I changed that along with the fuel accumulator and a bad fuel pump relay. The fuel pressure regulator is my next change because I also can smell the faint fuel sometimes at idle and the hot start continues. The problem is also beginning to affect cold start idle rpms.