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Advice please - Rapid backfire and misfire

Posted: 22 Jun 2016, 20:20
by VAN with a PLAN
Hello, hoping some of you can help. My van has been a joy to drive of late, particularly since winding the mixture screw out a touch at the MOT last month.

Today it died on me unexpectedly and refused to start, the symptoms would imply fuel starvation, which I have suffered on the odd, random occasion. My usual trick of removing the supply line from the carb and sucking some fuel through the pump resulted in an instant mouth full of fuel - yuk! Not a supply issue this time then.

I did some quick checking of HT leads, distributor etc. and eventually it started and idled nicely. 5-10 minutes down the road it began to backfire rapidly and was hesitant and misfiring. I was only 5-10 mins from home kept the revs up and nursed it on. After a few minutes it cleared and was pulling nice and cleanly and running well. 2 minutes later it's back to backfiring rapidly and running poorly.

Having parked it up for an hour I went back out and gave the connections another quick look over, nothing obvious. The van starts on the button but needs throttle to keep running, is running poorly and the revs drop even with a fixed throttle position.

Has anyone experienced these symptoms? I can't find anything that exactly matches this in the Wiki or Tech Archive.

Advice gladly received!

Thank you
Peter

Re: Advice please - Rapid backfire and misfire

Posted: 22 Jun 2016, 20:30
by marlinowner
Mine behaved similarly when there was water in the petrol tank, when I drained some from the tank into a glass jar there were two clear layers.

Re: Advice please - Rapid backfire and misfire

Posted: 22 Jun 2016, 20:58
by VAN with a PLAN
Interesting, that could be a relatively easy fix. Thank you.
Does that mean I would also have water in my float chamber?

Re: Advice please - Rapid backfire and misfire

Posted: 23 Jun 2016, 12:17
by kevtherev
VAN with a PLAN wrote:Interesting, that could be a relatively easy fix. Thank you.
Does that mean I would also have water in my float chamber?
Yes.

Re: Advice please - Rapid backfire and misfire

Posted: 23 Jun 2016, 12:18
by kevtherev
Also check the idle speed cut off is working.

Re: Advice please - Rapid backfire and misfire

Posted: 02 Jul 2016, 11:55
by VAN with a PLAN
Thanks Kev and Marlin. I wanted to get to this sooner but life keeps getting in the way!

I picked up a new fuel filter and replaced it while draining some fuel from the tank. The fuel was clear but there did appear to be a few droplets of water on the bottom of the jar. The fuel I drained out of the filter however was distinctly hazey.

It fired straight away but was really rough for 30+ seconds, it then cleared and has been running beautifully ever since.

Thanks again for your replies, they're always greatly appreciated.

I guess now I have to work out how water is getting in and put a stop to it!

Sent from my HTC 10 using Tapatalk

Re: Advice please - Rapid backfire and misfire

Posted: 02 Jul 2016, 14:40
by kevtherev
Usual suspects are perished breathers

Re: Advice please - Rapid backfire and misfire

Posted: 03 Jul 2016, 13:31
by VAN with a PLAN
Thanks Kev.

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