Mid 80's 25hp

[Paulz01]

I was out the other day and after cruising in with myself and father, I went to slow the boat down for the no wake zone and the motor just shut down. I went to restart it and it would just sputter. After getting towed in and letting the boat sit for about an hour, it started back up and ran for about 10min no problem. I then decided to take a little test run and took it down the lagoon and when I went to turn around, the same thing happend.

Today I cleaned out the carb and all gas lines, which were pretty damn clean. Got the motor running again and it was running great until I started reving it a little and then it started to back fire. What do you guys think this is? How could I fix this? I would love to get some time in on the water next weekend if possible. I love the fresh fish. LOL

 

[BaitThrower]

Re: Mid 80's 25hp

Check spark plugs and gap. Replace with new ones if old and check gap is 0.030". Also check no wires touching power head where they might heat up. then check and test ignition coils.

Also check fuel flow. Lines may be clean but if its got tiny air leak somewhere it might not be flowing fuel properly over time.

 

[jbjennings]

Re: Mid 80's 25hp

I think it's possible you may have a bad powerpack that's getting a short in it when it warms up. That's my only guess. The backfiring could be caused by bad timing, intermittent spark, or a bad vacuum leak. Just some ideas.
Hard to tell without looking. Any more info? The more descriptive, the better. When it ran good for 10min. after letting it cool off, did it run great wide open for that 10 min.?
Sorry I can't be more helpful,
JBJ

 

[Paulz01]

Re: Mid 80's 25hp

When I was coming in from fishing, right before the engine died, it was running great! I didnt have a single problem with it.

After playing around with it for a lil while today, I had it running for about 30min straight at a high idle and it was working great but when I was on and off the throttle, as I got to the higher rpm's, if I jump to fast, it backfires. If I gradually come on the throttle it will run stong upto a certain point where it then goes back to dieing out.