300e intermittant no hot start
 

About four times in the last six months, our 87 300E has intermittantly refused to start when hot. The engine cranks, but doesn't catch. It never seems to do it with any consistancy - once after sitting for about an hour and a half, took about 15 min of intermittant cranking to start. Another time, the car sat for about 1 minute, and took about a minute of cranking to start.

From searching previous posts, I suspect that it may be a fuel pressure leakdown, resulting in vapor lock, but i don't understand why it only seems to happen occasionally, and never after the car sits for the same length of time (granted, my diagnostic abilities are somewhat green)...

thanks,
anthony

Had the same problem. It turned out to be the fuel pump relay. When it wont start see if you can hear the fuel pump running. If not, check the fuel pump relay.

Thanks Dave,

Turns out it was the relay. After replacing it, haven't had a problem with starts in the five months the new part's been in the car.

I have the same problem
 

Thanks for this post. My 190E has been doing that when the engine is hot after long drives.

I will check both. BTW, what does the OVP look like next to the battery?

The OVP should be a red-topped relay with a plastic flip-up cap. Underneath the cap is a fuse. It's on the far right, behind the battery. The relay can be a pain to pull out of the socket...

-anthony

Still can't find it on my 1993 190E 2.6
 

Could it be that it is inside the fuse box to the far left on the driver side?

You need to pull the black plastic panel behind the battery on the pass. side of the engine bay to expose the relay bank. It can be a little tricky working it out from under the hood. Then the relay is to the right of all the other relays, set back a little bit.

-anthony

Thanks! I will check it out.
 

ok.