Misfire and cold start issues

[Tim 7-33]

Had a run out yesterday c25 miles, all good, last part single track 1 in 4, parked at the top on a grass verge. Walked 3 hours, back in the car, down the 1 in 4 and on to the flat there was a very definite misfire. Wouldn’t say it got worse but wasn’t great but did get home. Fired the car up tonight to investigate and would barely run, indeed stalled if left to idle. Nothing visibly loose or mechanically damaged. Very strong fuel smell. I suspect low speed up steep hill on a v hot day meant under bonnet temp got very high by the time I parked up but surely nothing would have cooked? Looked at a few threads on here but nothing seems to quite match my symptoms. Any thoughts? 96 500 by the way. Thanks, Tim

[sixor8]

The 100A fuse on the chassis starting to fail on my car caused it to run rough, over fuel and stall. It came off in one piece but fell apart when I touched it, corroded through.

[Belle427]

Just make sure you do not have an actual fuel leak too from the rubber hoses if the smell is strong.

[NiaLaurie]

I had similar sounding issues that gradually worsened over a year or so, so not a sudden as yours. It was the temperature sensor that goes to the ECU. Having the incorrect temp being indicated led to massive over-fuelling and petrol smell form the exhaust, and it would not idle until hot.

Its a cheap part to replace, and I have heard some people say that they get it replaced every year.

Good luck.