[FA18Driver]

Ok gang I have a problem that maybe you can help with. I took my boat out yesterday and all was ok until it got good and warm thru and thru. Then the starboard motor would idle ok but when I tryied to bring it up to say 900 or 1000 rpm it would just stumble and carry on, if I kick the throtle on up a bit it will clear up by about 1100 or 1200 rpm seemed to be fine. I thought I was feeling a slight miss but it was hard to tell for sure thou. My first guess is spark plugs or a bad wire/distributer cap? any ideas as to what else it could be? oh yea it is a 454 mag with carb.

 

[Iggy]

Sounds like a dirty carb.
Something causing an off-idle stumble.

 

[FA18Driver]

Well I kinda was thinking that but I just had the carbs done back in Jan. like I said it was fine till it got good and warm. Guess I will have to take out and see if it starts doing it as soon as I crank it it or if it waits till after it warms up again? I would think if it was a dirty carb it would do it all the time???

 

[Canada Jeff]

How old is your fuel, and fuel filter? I'd look at a tune up. If not that than your advance perhaps.

 

[FA18Driver]

Thanks Jeff, good idea about the advance.... never thought of it. Well when we did the carbs we pumped all the fuel out and replaced the filters as well so it should be fresh. I was kinda going with the tune up idea, will not hurt ot have new plugs and wire etc.... thanks again!!

 

[obnoxus]

when they went through them where did they put the accel pump setting,,, might just need a little more off idle fuel.

 

[FA18Driver]

Another idea there, I will have to look at it, I would think they put both of them the same but heck you never know, might be differnt!!

 

[OldMagicfloat]

Just a guess,but I would look at the cap,wires,plug set. In that direction. Sounds like a ignition problem,but a accel pump might also be something to look into

 

[gilla]

Shouldn't a bad wire or cap get worse with higher rpm?

Probably a lot of work but could swap carbs and see if the problem goes with it.



Gilla

 

[RumRunner]

Most likely not accelorator pump, if it happens under a steady RPM. If the carbs where just rebuilt, it could be some dirt, but it is most likely just your initial butterfly settings. Pretty easy to check and see what the engine wants. Start it up, get it to the RPM it runs poorly, and press on the accelorator pump arm this will add fuel without changing the amount of air the engine is seeing. If the RPM picks up/smooths out you're lean, gets worse you're rich.
You can try making a slight adjustment on the mixture screws, but most likely you'll need to close down your secondary butterflys a little further. There is a screw on the passenger side of the carburetor base plate to do this.

 

[FA18Driver]

Thanks Guys, I have all new parts Plugs wires caps rotors etc. for both motors so I am going to do that first just to get it out of the way. I also went ahead and got new fuel filters to put on too. I will try the test RumRunner suggested tomorrow afternoon. My buddy is gonna go with me and we will start with the easiest things to check if the tune up didn't help. Thanks for all the good ideas guys!!! You gave me a lot to look at but hey it could be any one of these things causing it....

 

[obnoxus]

And hey,,,I'm not doing anything today so if ya want to yank the boat up to Chicago real quick, ill give you a hand !!! ( your airplane has a hitch on it, doesn't it !!!???

 

[FA18Driver]

Hey sounds like a plan, I will hooker up and be there right after lunch...............

 

[obnoxus]

Skip lunch,,, I'll throw some steaks on the grill !!!!

 

[FA18Driver]

Now that is to good to pass up...... Man I wish I was closer to Chicago land right now

 

[obnoxus]

They are Filets to !!!

 

[FA18Driver]

Count me in............................... I'll bring the beer and Margarita mixing supplies......

 

[obnoxus]

Margarita,,,, you said the magic word !!!!

 

[FA18Driver]

Yep ain't nuttin better than to sit around the grill .... doin rita's and rib's

 

[OldMagicfloat]

So after all your grillin & chillin,what did you find out?? Is the problem fixed? Inquiry minds wanna know