Frizzlestick
Cadet
- Joined
- Jun 6, 2013
- Messages
- 7
I have an 87 Johnson, 50 HP. It was VRO, but that unit failed a few years back - so now I just mix 50:1 right at the tank.
The problem is a wandering idle of sorts. At certain RPMs, most notably at idle, it wanders. Like it's rough, then good, then rough, then good. At full throttle, and other points in the throttle, it's fine. At others, it has this wander about it.
Things I've checked:
I've run some sea-foam through the tank, and put some deep creep right into the throttle/carbs under load (to try and clean out the reeds), no change. I've also replaced the fuel line with no change.
Now the only thing that makes me scratch my head, is that if I shoot carb-cleaner in it when it's running, it runs well while I am shooting it, then once that burns through, it's right back to wandering. That has me scratching my head because I would think it's running lean/starved, and the carb cleaner is helping it - but with the plugs being wet(ish, not terribly bad or ineffective) makes me think it's rich(ish).
I would also think, that if it was the reed valves (gummed or cracked), that carb cleaner wouldn't have any temporarily improving effect on it?
Also, would like to add that sometimes, rarely, it's fine. Idles like a dream, motors about like a dream. But most of the time (90%?) it's wandering idle and this surging/wandering at certain RPMs (with full throttle being fine, and about half-ish throttle, and somewhere just above idle -- i can usually find a spot where it evens out in the firing).
Ideas? I'm scratching my head here. Plugs say "maybe a bit too wet", carb cleaner kinda tells me "maybe a bit too lean", loping tells me "maybe bad plug/spark/air in the line?"
The problem is a wandering idle of sorts. At certain RPMs, most notably at idle, it wanders. Like it's rough, then good, then rough, then good. At full throttle, and other points in the throttle, it's fine. At others, it has this wander about it.
Things I've checked:
- Compression : good in both cylinders - one was 133 PSI, the other was 139 PSI.
- Manual Choke/Primer Switch: In the right position and works correctly.
- Spark : The coils seem to be producing good spark, put a tester on both wires and they were arcing/lighting up fine (one better than the other, but the weaker one is still well in the acceptable range.
- Carbs: I had a mechanic do a rebuild on the carbs. New floats, needles, gaskets. They looked in good shape anyhow, but did it "just in case". They're fixed, so I can't adjust the mixture. Jets were clean.
- Fuel: Fresh fuel, 50:1. Ran Seafoam through one tank. New fuel lines from tank to motor, including primer bulb.
- Plugs: The plugs seem to be fine. They're a bit wetter than I expected, but not "jeez, this ain't burning nuttin'" wet. Pulling them and cleaning them has no noticeable effect.
I've run some sea-foam through the tank, and put some deep creep right into the throttle/carbs under load (to try and clean out the reeds), no change. I've also replaced the fuel line with no change.
Now the only thing that makes me scratch my head, is that if I shoot carb-cleaner in it when it's running, it runs well while I am shooting it, then once that burns through, it's right back to wandering. That has me scratching my head because I would think it's running lean/starved, and the carb cleaner is helping it - but with the plugs being wet(ish, not terribly bad or ineffective) makes me think it's rich(ish).
I would also think, that if it was the reed valves (gummed or cracked), that carb cleaner wouldn't have any temporarily improving effect on it?
Also, would like to add that sometimes, rarely, it's fine. Idles like a dream, motors about like a dream. But most of the time (90%?) it's wandering idle and this surging/wandering at certain RPMs (with full throttle being fine, and about half-ish throttle, and somewhere just above idle -- i can usually find a spot where it evens out in the firing).
Ideas? I'm scratching my head here. Plugs say "maybe a bit too wet", carb cleaner kinda tells me "maybe a bit too lean", loping tells me "maybe bad plug/spark/air in the line?"