V4 rough idle

[aaero12]

Re: V4 rough idle

Try pulling one plug wire at a time with the engine running, listen for a change in rpm. If the cylinder is firing properly, a drop in rpm will be noticed. Any plug wire removed that has no effect should be suspect of either bad plug, wire, associated coil, or ground. As for the plugs themselves not showing any signs of fouling, the plug that is not firing will only show your fuel/oil mix. If there is no combustion, there will be no sign other than wet with fuel.

 

[BF]

Re: V4 rough idle

if the trigger is intermittent/marginal maybe the plug fires just often enough to keep it from looking too wet. (?)

 

[ReelDrag]

Re: V4 rough idle

Why would an electrical problem only show up at idle. Anything above 1500 rpm and it runs perfect.

 

[ReelDrag]

Re: V4 rough idle

Ok, I put the timing light on each plug wire and it appears to be firing consistantly on all 4. What now?

 

[special88]

Re: V4 rough idle

I have the same problem with my 88hp Johnson V4. It runs great at top speed but idles rough and accelerates rough. Sometime it cuts out at idle I had the carbs rebuilt two weeks ago. new fuel pump, filter, gasline. My topic is under Special88 let me know if you get it figured out and I will do the same.

 

[ReelDrag]

Re: V4 rough idle

Will do special88. I just pulled the carb cover off and I don't see anything unusual going on in there, no flooding or gas spitting back.

 

[Walker]

Re: V4 rough idle

Does this motor hae a recirculation system?? Might test the check valves if it does.

 

[ReelDrag]

Re: V4 rough idle

Yes it does have a recirculation system. Have to pull the carbs off to get to them. One thing I noticed just now, when I restarted it a big plume of smoke came out. I premix so I don't see why this would happen unless it is flooding. I'm going to pull the carbs off and recheck the floats. While I'm at it I'll check the check valves.

 

[paperdesk]

Re: V4 rough idle

I'm wondering if you have reed/leaf valves in that motor? I'm not familiar with the newer models, but I have a v4 crosflow and it had the same problem until I replaced a bad leaf valve set. Parts only cost me $8 on e-bay!<br /><br />Just got it going today in fact! Now it's really purring!

 

[Walker]

Re: V4 rough idle

ReelDrag, the checkvalves should only allow flow in one direction. A syringe full of rubbing alcohol stuck in the hose works real good to test. The nipples on the port covers should be free both directions.

 

[ReelDrag]

Re: V4 rough idle

Ok, got the carbs off . Everything there looks good, floats ok, no crud. Unscrewed the recirculation ck valves and gas poured out of the hole. Is that normal? I'm quess the flow is supposed to go toward the port covers? How open are these things supposed to be, I can barely blow through them (got to quit smoking) in one direction, nothing in the other direction.

 

[Walker]

Re: V4 rough idle

They should be fairly free flowing one direction. They should flow towards the port covers. Gas pouring out indicates that they are not working properly.

 

[ReelDrag]

Re: V4 rough idle

Ok, thanks.I'll pick 4 of them up tomorrow at the dealer. Maybe it will be an easy fix.

 

[ReelDrag]

Re: V4 rough idle

I pulled the flywheel today to check the stator. I found a small crack in the top of the plastic housing. The plastic is also bubbled up in that spot about the size of a dime. It's in the rear of the stator on the top. Is this where the charge coil is located? Could this be causing my idle problem?

 

[Freezebear]

Re: V4 rough idle

Hey, what did you find on your motor? I have same problem. Check my post on a 60HP sneezing through top carb. Breaking down and taking it to dealer in the morning though. Mine also has a split and white goo oozing out the crack near what I guess is the power coil. The other ones look like stator coils to me. I have done everything to this motor and cannot figure it out. Will just let dealer replace and time the thing and I will maintain it that way when i get it back.