Gremlins!! I think it’s Gremlins!!

[bullie]

I am working on a 1995 DT4 Suzuki 4 Hp Longshaft and it is driving me bonkers. It will start with a 1/4 pull and run like is supposed to from a very slow idle to as wide open as I will let it go in the barrel for a long time. Then it won’t do a thing. Spark will jump a full 1/2 inch. Compression is 92 lbs. I checked the key to see if the key was sheared. All good.

I thought it was a carb issue (one of the ears where the float pin goes through is broken on the original carb), so I bought another one and installed it today. It started on the 2nd or 3rd pull. I ran it in the barrel up and down, adjusted the carb, turned it off and on…etc. Checked temps with laser thermometer…generally checked it out and figured it was ready to go. Went back out after an hour or so and nothing. It would cough a bit but would not start. Plug is wet but has good spark. Checked compression again 92 lbs. I pulled off the starter and spun it with my drill. Nothing. I pulled the flywheel and checked the key. All good. I put it back together and spin it several times with the drill. Then it STARTS. Idles down perfect. I rev it up and down, in and out of gear, stare at it… then a little cough…and no start again. I have no idea. It may have Gremlins.

[PugetSoundBoater]

You said you replaced the carb. If it was a "good" used one, did you clean out the old gas, give it a look to see how it was inside? Knowing how thorough you are, i think you probably did.
You have barked up all the right trees, but really didn’t mention anything on the 2nd carb, Gremlins can reside in there.

"Some people want to know how a watch works, others just want to know what time it is"
Robbie Robertson

[bullie]

Yeah, forgot to mention that. Took it apart, cleaned it, and reassembled. It’s doing the same thing it did with the original carb. I thought the float was sticking shut due to the pin tilting and not allowing any gas to enter the bowl. I thought wrong again.

[billw]

I know you say it always has spark but it sure sounds like it is losing spark! Wet plug, won’t start after a run, etc. Just for yucks, did you try another spark plug? If it were me, I would put my highly visible timing light on the plug wire, verify that it is flashing well when the engine is running, then observe it when the engine won’t start. If it doesn’t flash, either the plug is fouled or there is, in fact, no spark. However, given the fact that it’s a Jap motor, the chance of its having no spark is slim to none.

As I write this, it also occurs to me that if the plug is wet with good spark, maybe is is flooding somehow when left to sit, like a weeping float valve or hole in a fuel pump diaphragm?

Long live American manufacturing!

[bullie]

The local parts place didn’t have the correct plug but this one is sparking. I tried again with my open air tester and my timing light. Bright blue spark and flashing brightly. I also disconnected the fuel pump from the side of the motor and pulled it over. No fuel leaking. I’m stumped.

I know this is weird, but it sounds different when it won’t start. Kinda backfires a little through the carb. I removed the carb and and pulled the motor over and the reed appears to open slightly and close. It’s so weird how it goes from running like new to nothing.

I tried to start it this morning…nothing doing.

[bullie]

I have also tried using starting fluid when it won’t start. No go.

[nj-boatbuilder57]

I’m no expert, but it seems to me if starting fluid won’t ignite, then you don’t have a spark. That’s typically diethyl ether + heptane and will explode just by looking at it!

Also….while I realize you’re in the midst of troubleshooting & this might not need to be said, it ought to be noted: starter fluid is not great for use on a 2-stroke, as it offers no lubrication. If the motor does start, you’re running it dry.

[bullie]

I hear some sort of popping like pressure being released that sounds like it’s coming from under the flywheel. I had it off and didn’t see any oil like there was a bad seal but there is a definite popping sound. I’ll see if I can record it.

[bullie]

https://youtu.be/cSpavBYoMQo

https://youtu.be/PXMJEXSbvf0

Slow and fast. It’s a popping sound. Not a rubbing sound. I’m gonna pull the flywheel again.

[bullie]

The plastic disc around the crank was popping up and down. That was the sound.

[Author]

Posts