1988 Force 125 with surging issue

[Jwolfecc]

I have a 1988 Force 125 that has been running well after having the carbs rebuilt and a new shifter and cables installed. I am now having an issue. The engine starts and runs at slower speeds well, but when I give it throttle to get up on plane it only gets up to about half the speed that it normally does, surges as if it were going to run fine for a second or two but then bogs back down to half speed for a few seconds only to surge and bog again and again. I have done a compression check and all cylinders have around 120. I am running new plugs. I haven't tried new fuel since the issue has started. Any advise would be greatly appreciated!!

 

[SkiDad]

Take a buddy with you and have them Squeze the bulb when this is happening. Sounds fuel related. Probably the bulb or the fuel pump diaphragm.

 

[Jiggz]

Buy a G2 Fram clear fuel filter from Walmart for less than $5. Install it between the fuel pump outlet and the carb's inlet. The filter even comes with hose clamps so it is only a matter of cutting the existing fuel hose and clamping in the filter. Now prime the fuel system. Do a test ran at the water with the engine cowl off. Watch the clear fuel filter while running at WOT. It should at least stay half full if not more. If it empties you have fuel delivery problem. If it stays full you have carburetion problem or could be electrical and or could be reed problem.

 

[jerryjerry05]

Run with the hood off.
Possible the exhaust hose​ at the rear cowl is leaking and choking the motor out.

Check the fuel pump diaphragm.

Do the filter thing that Jiggz suggested.

ANY inline connectors? The originals were crap and the Ethanol eats the rubber and lets it suck air.

Check the hoses for soft or crumbling.

Check the tank vent, make sure it's open?

 

[Jwolfecc]

Thank you all for the information! SkiDad, I have squeezed the bulb while having the issue with no positive results. Sorry guys, I forgot to mention that when I had the carbs rebuilt, they rebuilt the fuel pump. This doesn't mean that it could not still be a problem. I will pick up that filter this weekend and get it installed. I shall do all other suggested checks and let you know how I make out. Think I should do the diaphragm check? Thanks again!

 

[Jwolfecc]

No time to get to Walmart between soccer games, just the local auto parts store. They did not have the G2 so I wanted to wait to get to Walmart. I did buy an inline spark tester though and found that I have no spark on the top cylinder at idle. What is the next best troubleshooting tactic?

 

[Jiggz]

No spark on the top cylinder, then switch the ignition coil with a known working ignition coil, i.e. switch #1 with #2. If the no spark follows to #2 cylinder than the ignition coil is bad. If not, then the next move is to switch CDM's.

 

[Jwolfecc]

Thanks Jiggs, I will get on that as soon as I can. Is that how the cylinder numbers are, one at the top and four at the bottom?

 

[Jwolfecc]

Sorry, Jiggz

 

[Jiggz]

That is correct. Cylinder numbering starts from the top (closest to the flywheel) to the bottom. When I say switch it means physically switching all the associated wirings not just the plug wire otherwise you will have back fire which can seriously damage the engine.

 

[Jwolfecc]

Swapped coils and the no spark went to cylinder #2. Looking for a coil now.

 

[Jiggz]

You're on the right track.

 

[Jwolfecc]

Just got the new coil in from boats.net. When I was ordering the blue 685475, I thought that is what I would be getting. Not quite, I got a black 300-888791. I called customer service and the swear that it would work. We will see!

 

[Jwolfecc]

So far so good, got spark! Maybe get out on the water tomorrow between soccer games for a test run.

 

[Jiggz]

Great. You should be able to tell if the engine will actually perform good even out of the water. It should have a smooth idle and you can also rev it intermittently up to about 2000~2500 lasting a couple of seconds and it should accelerate smoothly. Now this is all accurate if you have it submerged in a trash can. However, if you have it on muffs, it may not be as realistic as it is on water. But if the lake is not that far, you can always wait for tomorrow to do the test run.

Hopefully, you were able to install that clear filter mentioned earlier. If you encounter any surging during the test and you did install the filter, while doing test run you might want to run the engine with the cowl off just to see the clear fuel filter if it stays full or not.

 

[Jwolfecc]

Bad news... My daughter lost her soccer game. Great news, the boat runs great! I have not done the G2 yet, but I can see how it can help with future troubleshooting. I will get to that soon. Thank you for the help and advice!

 

[Jiggz]

Congrats and enjoy!