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43gl intermittent misfire at WOT Help

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davej

New member
"Hi

I'm new to this si

"Hi

I'm new to this site but stumbled across it and thought there were lots of helpful people who know what they are talking about! It is a 2000 4.3gl, had the boat since new. First time use this season seems like a mis-fire at full RPM. Replaced plugs, leads, cleaned distibutor and rotar arm. Took boat out again and problem now at 3/4 and full throttle but not when getting onto the plane. Any help or suggestions would be greatly appreciated.
Thanks Dave
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"
 
"Make sure you have fresh plug

"Make sure you have fresh plug wires, cap and rotor. Crossfire is likely if they're all old. If you have a points ignition, make sure everything is up to spec. Old gas? It's not actually a misfire, as such, but can be a problem."
 
"Thanks for your quick reply.

"Thanks for your quick reply. Bought new plug wires, cleaned cap and rotor (new ones on order). I have put fresh fuel in it but I am not sure how much old fuel was in before. Not too sure if it has points or not I am going to buy the electronic and fuel system manual to see how to check the timing. The noise sounded like a ping out of the exhaust with momentary loss of power. Could that be a misfire?"
 
"If you're not sure about

"If you're not sure about points, look at it.

That could be a backfire but there are many causes."
 
The boat runs fine at full thr

The boat runs fine at full throttle coming onto the plane with 5 people and a full tank of fule but as the revs pick up the problem starts any ideas?
 
"David, try to hotwire the pos

"David, try to hotwire the positive of the coil (run a wire straight from the + of the battery) and then try again. You could have a defective ignition switch or corroded/loose wiring connections between the ignition switch and the coil, or a neutral safety switch acting-up. If the symptoms clear-up, then you know what to look for."
 
"Thank you very much. I can&#3

"Thank you very much. I can't get to the boat until the weekend but I will give this a try and let you know how I get on.

Thanks again,
Dave"
 
"Just one thing I forgot to ad

"Just one thing I forgot to add: remove the "jumper" after testing, otherwise the engine won't stop even if you turn the key or the battery switch off!!"
 
"I am having a similar problem

"I am having a similar problem so I am interested to see how you solve your issue. My starboard engine runs a little rough at idle and when I get the revs up when trying to plane it misses randomly at around 3500-4000 RPM. The port engine runs notably smoother. I changed plugs,wires,cap,rotor and it didnt seem to make a lot of difference. One thing I wonder about was if a vacum leak could have a similar affect. I notice that the intake manifold has some silicone around it which would make me think it has been off, I checked all the bolts and was able to tighten 3 of them a little and the water neck bolts a little as well. I fired it up and I think it runs better at idle, I was not able to take it out today but I will take it for a sea trial at plane in the next few days. My other thoughts were perhaps changing the coil. I also wondered if it might be related to old gas, the boat had been sitting since last Sept. and only ran a few short times. This I think is unlikely though as the port engine runs like a top.

Any other suggestions?"
 
"I took my boat out this weeke

"I took my boat out this weekend armed with the wire that EL Pescador had recomended to hotwire the coil to to the battery, but as I had already orderd a new rotor, cap and fuel filter I fitted them first. The old fuel filter seemed to have water in it when I drained it so I thought I would test it with the new parts before hotwiring it. She started on the first turn of the key and idled a lot better. Let her warm up and then took her out, the boat flew onto the plane and belted up to top speed without missing a beat, it was like when the engine was brand new! A big thanks to Jim N and EL Pescador who took time out of their day to help me with my problem some great tips and I will keep them banked for the future.

Thanks again!"
 
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