Engine Mis-Fire

Brrok_lands · Post by **Brrok_lands** » Mon Feb 02, 2015 1:41 pm

Following on from my previous post (http://forum.suzukiclubuk.co.uk/vi ... 13&t=11383) where I was blaming the original carb on my Samurai for the engine running roughly, I finally got it running sweetly after a plug change and following the instructions for setting up the carb. Well at the weekend the mis-fire was back big time. Mess about with it, swopping plugs, I was loather to touch the carb after the last time, and got it running sweetly again.

This morning I thought struck me, my drive is quite steep. The first time it was running rough it was parked nose down and the problem was with No1 cylinder. This time it was parked nose up and the problem was with No 4 cylinder. ie the lowest cylinder.

Now I'm aware that there is a potential problem with the original carb on inclines when off roading.

I'm thinking it may be over fuelling and the surplus is running down to the lowest cylinder flooding it, or I'm being stupid? Any views from the wise.

Post by **Jordi** » Mon Feb 02, 2015 7:36 pm

Could still be the carb.

Have you changed the dizzy cap and leads?

Brrok_lands · Post by **Brrok_lands** » Mon Feb 02, 2015 8:11 pm

Yes, cap, rotor and leads are all new. I also have 4 Accuspark spark plug testers so I can see that all the plugs are receiving a spark as they should be.

donkeychomp · Post by **donkeychomp** » Mon Feb 02, 2015 9:05 pm

Try leaving it overnight on level ground and then see what happens. If no more misfire then you have answered your own question!

Post by **ScottieJ** » Mon Feb 02, 2015 11:07 pm

Run it for a little bit but before the missfire clears (if it does) turn it off pull all the plugs and check to see if any are wet and washed?

Could have a failure in the carb gasket or inlet manifolf gasket allowing coolant into the manifold.

Brrok_lands · Post by **Brrok_lands** » Tue Feb 03, 2015 10:49 am

Well Donkeychomps has sort of got it. Was running really rough this morning after being parked nose up since Sunday when I had got it running OK. In fact so badly it could hardly drive itself out of the drive. I couldn't park elsewhere as it was SORN with no MOT or Insurance. Finally got it out of the drive just and went the long way to the MOT station giving it a serious Italian tune up. Mis fire cleared after about a mile. Running great by the time I got to the test station and passed test well within emission limits and with no advisories - well pleased.

So I'm guessing it is something to do with the carb not liking sitting at an angle either nose up or nose down.

Post by **Jordi** » Tue Feb 03, 2015 11:20 am

Just how steep is your drive?

Brrok_lands · Post by **Brrok_lands** » Tue Feb 03, 2015 6:40 pm

About 1 in 3.5 or 30% or 18 deg. Quite steep for a road but nothing for an off road course.

It's sat on a level car park all day and then started on the button with no rough running so now I'm more convinced than ever it has something to do with the slope.

donkeychomp · Post by **donkeychomp** » Tue Feb 03, 2015 9:35 pm

Glad I finally got something answered right! What carb are you running?

Brrok_lands · Post by **Brrok_lands** » Tue Feb 03, 2015 10:46 pm

I still have the original Aisin carb on it.

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