87 125 force misfire after warm

[Jimay]

Just bought the boat runs great at low rpms when I first kick the throttle down it sputters a little the kicks in gear and does really well but when I throttle down and try to throttle up again it won't rev over 2000 rpm or go fast enough to plain out if I turn motor off for say a hour maybe little less itl be fine for one burst then back to 2000 rpm and if I keep it throttled up on the first run itl keep running wide open until I throttle down again I've cleaned the carbs and they were spotless and replaced plugs, also it will use 18 gallons of gas in 5 hours of idle

 

[Jiggz]

Re: 87 125 force misfire after warm

First, read the link and synch sticky posts on the very top of this forum. Make sure you do exactly what it says. Second, install a clear fuel filter ( get one from auto parts of the same size hose connectors, usually 1/4" or 3/8") between the fuel pump outlet and the carbs inlet. Do a test run again and if problem persists, check the status of the clear fuel filter is it at least 3/4 full? If not you have fuel delivery problem either with the fuel pump, leaky fuel hose, clogged pick up tube or tank vent. If it is full, then you have carb problems or linkage problems with the carb or timing. Do a compression test and post results.

 

[Jimay]

Re: 87 125 force misfire after warm

It's not a fuel problem no junk in carbs and burning plenty when I say I cleaned the carbs I'm not insinuating I wiped down the outsides I took the boat to my bike mechanic had him clean the carbs absolutely no change won't have chance to test compression until tomorrow but if I had a dead cylinder it should be dead all the time not just when it gets warm correct and yes ball is tight, pump is pumping and suck tube is free of junk and have already ran on a 6 gal plastic tank that is clean

 

[Jiggz]

Re: 87 125 force misfire after warm

You seem to have covered all bases with all possibilities and there's not a whole lot I can offer. Maybe others with more experience will chime in. You have a perfectly working fuel delivery system with no clog or leakage in the fuel hoses and pick up tube since you found no junk in the carbs by wiping the outsides and having them inspected by a bike mechanic. I'm sure someone with more experience and knowledge will chime in to resolve your problem.

 

[Jimay]

Re: 87 125 force misfire after warm

Was in a rush on that last post, I've went through all the fuel symptoms already reading through old post

 

[jerryjerry05]

Re: 87 125 force misfire after warm

Compression test.
Spark test.
Then check the fuel pump diaphragm.
The fuel recirc system might be clogged.
You in the US? Profile, location?
I ask because Ethanol in US gas is causing problems with older hoses.
It delaminates the inside of some hoses and it shuts off the flow.
Excessive use of fuel can be a bad diaphragm in the pump.

 

[Jimay]

Re: 87 125 force misfire after warm

145 compression on all cylinders runs fine cold not sure how to test coils other than putting power tester on the plug wires and certainly see a issue on water where's the guy that had this same problem payed 50 cents and fixed it, I'm in the us running in fresh water

 

[Jimay]

Re: 87 125 force misfire after warm

I have spark on all 4 plugs I have good compression clean carbs clean fuel the way it's acting I'm sure a coil Is not working once it warms up but don't want to spend over 100 on a coil if I need a stator

 

[jerryjerry05]

Re: 87 125 force misfire after warm

Try Outboard Ignition . com
Or CDI ignition.
Both have test procedures for these motors.
I've found the trigger leads where they connect at the terminal strip, the spade connector breaks under the shrink wrap.
The wire is a very thin/tiny wire and breaks and seems to be ok under the shrink wrap but can be broken.
It may run fine until you move the throttle.

 

[MickLovin]

Re: 87 125 force misfire after warm

When it is warm have you tried taking one plug out at a time to see if the motor runs any different? Sounds like you are loosing a cylinder, possibly from a coil or as jerryjerry has stated it can be the trigger.