1996 Force 90 HP intermittently won't start when engine is warm

[PagosaFish]

Hello all. I am having an issue with my 1996 90 HP Force engine starting when it's warm. There are 2 issues. Most of the time, I go fishing with it about once every 2 months, so the boat sits in my garage for weeks at a time. I live in Colorado at 7500 ft. When I take the boat out, most of the time it will take 5-6 turnovers to get it to start, and that is even with the fast idle up and me choking the engine to start it. But once it runs, it runs great. I have 2 lakes I fish at. One lake is a very small "no wake" lake. When I use the boat on this lake, the motor runs great and starts every time I fire it up, but I never plane the boat since it is a no wake lake. On the other lake I fish, I can run the boat on a plane, about 90% of the time I have to get towed in because the motor won't start after fishing for a few hours and starting and stopping the engine going from fishing hole to fishing hole. Once I get the engine started, I drive over to the fishing hole, which is usually about a 10 min drive in the boat going about 30mph. The motor runs great. I fish for 30 mins or so, then go to the next hole. After the 2nd or 3rd hole, I try to fire the engine back up, and it won't start. I have worn out my battery trying to get it to start. There is no coughing of the engine trying to start at all. It just turns over. I get towed in, then when I get the boat home an hour and a half later, the engine fires up just fine. I have replaced the water pump, cleaned out all in the 3 carbs. There is water coming out of the pea hole, so I know the water pump is working, This has been going on for about 2 years. In spring of 2015 I took it out to the big lake. It ran fine, starting every time. I ran it for about 3 hours, starting it, planing up for 15 mins or so, then stopping it for 15 mins, and it started every time. The air temp outside was about 60 degrees, so it was much cooler than in the summer time. Later that summer I took it out, and did the same thing, the engine wouldn't start after the 3rd time stopping. This spring 2016 I recently took the thermostat out just to check it. I left it out, and ran the boat for over 4 hours with no problems, but the outside temp was only 66 degrees. I checked the thermostat by pouring hot water over it. It opened up just fine, so I don't think I have fixed it. Any ideas you guys could give me would be great. I have a fuel pump diaphragm kit on order, and will replace it next week.

 

[pnwboat]

Might want to see if you are getting any ignition spark when it's not starting. This will help determine which path to take to fix the problem.

 

[PagosaFish]

Thanks much. Could you let me know how to do that so I don't blow the CDM? I can't remember the exact process.

 

[SkiDad]

you could put a timing light on the wires to see if they are getting spark - or you could try an inline spark tester.

Are you also starting in fast idle when it's warm ? have you checked all your electrical connections for corrosion ? have you changed your primer bulb / is it getting firm ?

 

[tommarvin]

Your right, a timing light is better and faster way to check for spark.
When old ignition parts get hot/overheat they don't hot start until they cool down. I have heard this problem many times it's very common.
Do you have the correct jets in carbs for 7500 feet ? Our 125hp 6000 feet and up needs size .086 jets in the carbs.
Be sure to put the stat back in.

 

[PagosaFish]

Thanks guys. Regarding the timing light, I don't have one. Are they expensive and where would you recommend to purchase one? On the jets, yes I have changed them out for high altitude. I have checked my electrical connections and there is no corrosion. I have tried starting in fast idle when it's warm, and it still won't start. I also tried priming the bulb when it was warm and it still didn't start.

 

[tommarvin]

I don't know if you can test a FAILING ignition part, or do you have to wait for the part completely fail to find it ?
Again, when old ignition parts get hot/overheat they won't hot start until they cool down. It varies, 10 to 15 min is what I've read here.

 

[flyingscott]

You can absolutely test a failing part just wait until it happens and perform your tests then. Buy a spark checker at the auto parts store make sure you get one that's adjustable.

 

[PagosaFish]

We'll do. I'll buy a spark checker then let you know How it turns out. Thanks for the help.

 

[tommarvin]

This is another boat runs fine, but won't" hot start."
You could be proactive and look at the backs of all the coils, cdi packs, for burns or burning. If no burns, you could remove the flywheel, and look for burn marks in the stator, check every inch of wiring of stator, trigger, check the magnet on the flywheel still glued down tight? Pull hard on all wires going into all connectors.
Are all the ground wires tight , not broken, check everything vary carefully.