90 hp mariner problem

[Fisherman45]

I have a 1987 90hp mariner. It starts and idles real good but once I give it anything past 1/4 throttle it starts missing and sputtering never gets up to speed. I went out to my spot on the lake and used the trolling motor for a few hours and when I went to leave is when it started acting up. I have rebuilt the fuel pump recently and replaced the plug wires. Any Ideas what could be wrong. I am in Stacy and haven't found anyone near that can look at it.

[Smellson]

You said you replaced the plug wires, but did you replace the plugs? Sounds like the same problem I had before and new plugs took care of it.

[Fisherman45]

I didn't replace the plugs they all looked to be firing. but I will try those.

[boatfixer]

2 things come to mind. clogged or partially clogged high speed jet. Ignition is the other.

Try choking it when this happens. If it picks up, you know its starving for gas.

The other problem could be the high speed side of the stator. The ignition system works off 2 different windings in the stator, low speed and high speed. The high speed starts taking over right in that rpm range you are experiencing problems in.

Try hooking a timing light to the plug wires and watch the light as you accelerate and watch for the light to flicker erradically in unison with the missing you are describing. If you find you have an ignition problem, I'd suggest taking it to a reputable shop for further testing. There is also a chance you have a bad switch box and there are some specific trouble shooting checks that need to be done. Very exspensive ignition components to just start replacing unless you are certain you know whats bad.

[Fisherman45]

Thanks Bruce I don't know about the timing light as this thing sits here with no load out of the lake and the water mufflers on and revs up real nice it is when it gets into the lake and has a load that it sputters and only gets to about 10 mph. I am looking at the high speed jets first. I have a mariner motor repair guide for the motor I am pretty sure I tried choking when I first ran into the problem but will retry that also. Otherwise I am looking for a mariner person in the NE metro any suggestions would be great.

Thanks

[BoxMN]

FWIW, we had a 87 Merc, same motor. Only prob we ever had was a stator, but it went out like a light bulb, if I recall. Working one minute, not the next. I knwo that doesn't help you. We also started using hotter plugs on advice of mechanic, and that made motor run better. Can't recall the numbers thought, been about 12 years...

For service, Nelson's in WBL would work on Mariners. Dennis is great, and I believe another good guy is John there.

Good luck.

[Fisherman45]

After going through the carbs and then the stator I found the 2 yellow wires coming out of the stator had become brittle and were shorting out no way to fix them as they are molded into the stator. I have a new stator on order I hope that does the trick Thanks everyone for the tips and advice.

Bob

[BoxMN]

Good to hear you found it! I bet you won't have another problem with that motor!