470 fouls plugs/motor swap

[BudFan]

I have an '86 Mercruiser with a 170 hp 4 cylinder that was fouling plugs after every other trip last year. I use my boat for trolling. A friend leaned out the carb last year which helped, but did not totally solve the problem. I have owned my boat, Rinker V190, for 8 years and did not have any major problems with my motor or fouling plugs until last year. The temp has been running on the cool side. My first trip this year was tonight, my plugs fouled again and I didn't get it running. I swapped out the wet plugs and still no go. What should I look for to try and cure this? I have read that this is a problem motor, if I decide/can afford to swap motors, what motor would bolt up and drop in.

 

[jeff13601]

Re: 470 fouls plugs/motor swap

If the plugs are fouling while trolling you might try getting trolling bags. This will allow you to bump up your rpms and also gives you better control

 

[jeff13601]

Re: 470 fouls plugs/motor swap

and did you check for spark at your plugs?

 

[cosander]

Re: 470 fouls plugs/motor swap

maybe your thermostat is stuck open

 

[MrBill]

Re: 470 fouls plugs/motor swap

Since you are "wet" fouling the usual causes are most of the things you've already checked out. Beyond air/fuel mixture being too rich and extended periods of low speed driving, other causes may be; choke stuck on, electrical issues or the plug heat range may be too cold. A fairly easy, not too expensive check would be trying a higher heat set of plugs. Short of detailed diagnosis, this might help enough.

 

[sshipp]

Re: 470 fouls plugs/motor swap

470 is not necessarily a problem motor. Put 4" heat exchanger and mount an alternator to replace the stator and the motors are as good as any. I have twin 470s with 1600 hours and they still work fine. Wet fouling can be either fuel related (carb, choke) or elctrical (no burn). I agree with the above posters. Check plug spark and choke if ok, try hotter plug

 

[Bondo]

Re: 470 fouls plugs/motor swap

for 8 years and did not have any major problems with my motor or fouling plugs until last year.

Rebuild the Carb........... <br />

if I decide/can afford to swap motors, what motor would bolt up and drop in. <br />

There is No "Drop-In"........<br /><br />It'll be Much More Work than that.......

 

[BudFan]

Re: 470 fouls plugs/motor swap

Thanks for everyone's reply. I replaced the thermostat last year, but still running on the cool side. I did not replace the plugs after winterizing from last year, should I have done that? The throttle shifter also got loose and is slipping. Is that shot also?