1990 Four Winns 225 Sundowner backfires!

K

kmiller633

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I have a 1990 Four Winns 225 Sundowner with the 5.8L engine and only 400 hours. I have taken the boat out 4 times in the last 6 days; the first three times everything worked perfectly and the boat ran @ speeds as fast as 40 and did not have any issues. Then the last 3 times at various speeds and conditions it abruptly lost power and backfired through the carb. I throttled back to idle and it still backfired some but kept running and backfired much less. I could then power back up and run fine for sometimes an hour or sometimes a moment or a few minutes.

I am not sure where to begin troubleshooting since it is not consistent.

Any ideas?

Thanks!![/SIZE]
 
H

HT32BSX115

Supreme Mariner
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Dec 8, 2005
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Re: 1990 Four Winns 225 Sundowner backfires!

kmiller633 said:
I have a 1990 Four Winns 225 Sundowner with the 5.8L engine and only 400 hours. I have taken the boat out 4 times in the last 6 days; the first three times everything worked perfectly and the boat ran @ speeds as fast as 40 and did not have any issues. Then the last 3 times at various speeds and conditions it abruptly lost power and backfired through the carb. I throttled back to idle and it still backfired some but kept running and backfired much less. I could then power back up and run fine for sometimes an hour or sometimes a moment or a few minutes.

I am not sure where to begin troubleshooting since it is not consistent.

Any ideas?

Thanks!![/SIZE]
Click to expand...


Howdy, Welcome aboard!


Well, aside from all the ignition & carburetion possibilities,

You might have a look at compression. AN engine that otherwise runs fine and abruptly starts backfiring could have a burnt valve, broken piston or ring, or other problem (from a detonation event). Also, if the choke as been stuck on any length of time, (or you're running REALLY old fuel) you could also have a carbon deposit glowing on a fouled plug or someplace in the combustion chamber that might cause it.(it may also Run-on (or "diesel")

Timing can also be a problem. If you have old spark plug wires, there could be some flash-over.


Regards,


Rick
 
K

kmiller633

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Re: 1990 Four Winns 225 Sundowner backfires!

Thanks for providing feedback and a place to start. I'll go through the plugs, wires, distributor and points tonight and see if anything jumps out at me. I do have some old fuel, about 2 years old, that I am burning through.

Should I add anything to the fuel like a stabilizer?

Thanks!!! :)
 
H

HT32BSX115

Supreme Mariner
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Messages
10,083
Re: 1990 Four Winns 225 Sundowner backfires!

kmiller633 said:
Thanks for providing feedback and a place to start. I'll go through the plugs, wires, distributor and points tonight and see if anything jumps out at me. I do have some old fuel, about 2 years old, that I am burning through.

Should I add anything to the fuel like a stabilizer?

Thanks!!! :)
Click to expand...


I have run 2 year old fuel......... I don't know if Stabil was added at any time. If it wasn't added when it was stored, adding it now will not help.

The best thing you could do would be to drain out the gas and fill with fresh. See if that helps (after checking filters, in-tank fuel pickup/strainer, etc)

If you want to "run-through" old fuel, mix it with fresh fuel 10:1 or so (10 gallons fresh to 1 gallon "old" . Don't run it straight.
 
K

kmiller633

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Re: 1990 Four Winns 225 Sundowner backfires!

I did mix it with fresh fuel, about 1/2 tank so I'll check the other things and see if I can figure it out.

Thanks again!
 
K

kmiller633

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Re: 1990 Four Winns 225 Sundowner backfires!

I went through everything last night and it all appears to be ok but I am a little concerned about the points and possibly the distributor cap. The points seem to be making contact way out on the edge and it looks like a half moon where the contact is. The distributor cap has a line running from the center out to the edge but I can't tell if it is a crack or just the way it is made.

Should I change the distributor cap/points, regap and test run?
 
H

HT32BSX115

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Messages
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Re: 1990 Four Winns 225 Sundowner backfires!

If that stuff is old or you don't know when (or if ) it was changed. That would be a good place to start....
 
K

kmiller633

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Re: 1990 Four Winns 225 Sundowner backfires!

Would you recommend converting my ignition and getting rid of the points? Any recommendation and or advise? Thanks!
 
K

kmiller633

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Joined
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Messages
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Re: 1990 Four Winns 225 Sundowner backfires!

I discovered a crack in the distributor cap which I believe was causing the engine to backfire. I replaced the distributor cap and converted to an electronic ignition. Everything runs perfectly! I can get to a top speed of abut 42MPH at about 4500 rpms and the boat planes out very quickly.

Sweet success!

Thanks for the feedback and suggestions!
 
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