Engine stutter.

[Themanofsteel]

I have a 1988 Force Outboard 85hp. It recently seemed to bog down or loose power at full throttle so I replaced the fuel pump diaphragm and gasket. Now it seems to intermittently stutter or shake in neutral or throttle. I attached a picture showing the diaphragm. You can see it can't really be put on backward or anything. Did I do something wrong? Here is a Dropbox link to hear what it does. https://www.dropbox.com/s/c3guj06jbg..._2255.m4v?dl=0

 

[Jiggz]

I'm not sure how you identify the fuel pump to be the sole source of the problem. Maybe you should instead just installed a clear fuel filter between the fuel pump outlet and the carbs inlet. A G2 fuel filter from walmart will do as long as it is clear. In this way you can monitor the filter if it stays at least 1/2 full or gets empty. If it gets empty then it is a fuel delivery problem. If it stays full then it could be carburetion, electrical or even reed problem.

 

[Themanofsteel]

What is reed problem?

 

[Themanofsteel]

Well I took a part the Fuel Pump again and I think I put the Gasket on the wrong side of the Diaphragm. It works fine now.

 

[Jiggz]

I still recommend a clear fuel filter for future troubleshooting and as a secondary filter. But that is just me, it is not required but highly recommended.

 

[Themanofsteel]

The fuel filter is just a wire mesh. Replace that. There are no other filters.

 

[Themanofsteel]

Thanks for all you input Jiggz.
So I took my boat out and it still seems to lack power. Could only go about 10 mph. Then, suddenly it bursts forward by itself and accelerates to around 20 mph. If I reduce speed and try full throttle again, same thing. It only goes about 10mph then without warning picks up speed and holds until I throttle down. Also, the motor stutters when throttling. Seems to sort of gallop.

 

[Simple_Man]

Do like Jiggz said install a clear fuel filter between the fuel pump and the carbs. then run the boat without the cowl. with someone watching the filter it should stay half full or more, if it doesn't then you have a fuel delivery problem if it does then most likely a carb problem. oh and did you do a compression check yet

 

[Themanofsteel]

Ok. Have not done compression check. Also. What is cowl?

 

[Jiggz]

He is referring to the top engine cover which is also called cowl or cowling.

 

[Themanofsteel]

Thanks Jiggz & Simple_Man. Let me all try this.

 

[Themanofsteel]

Just FYI, I recently changed the Starter and Solinoid. The starter was not working. Not sure if this could play a role in it.

 

[Jiggz]

Since the engine is starting and running albeit not up to par, it indicates the starter and solenoid are working accordingly. The RPM surges are mostly result of fuel delivery problem. The Fram G2 clear fuel filter costs less than $5 and even comes with hose clamps at WM. All you need to do is to cut the fuel line connecting between the fuel pump outlet and the carb's inlet and install the clear fuel filter. It will be a very big help with your troubleshooting. Please do this and report your findings if the clear fuel filter stays at least 1/2 full or gets empty. From there we can pinpoint mostly where the problem is.

 

[Themanofsteel]

Ok Jiggz. Thanks. I'll definitely update on the result once I've done it.

 

[Themanofsteel]

No Title

So here is a video showing the results with the filter. https://www.dropbox.com/s/pt3kr63ttpw5n5p/video aug 29, 11 08 18 am.mov?dl=0 Looks like it fills up more than half way.

I have another question about some green fluid that pools up at the bottom of the Carb air cover

 

[Themanofsteel]

So I used a spark tester and found that the top plug wasn't sparking at all. Come to find out that a wire behind this cover was broke. Couldnt see it inside the insulation but it popped right out. Top plug sparking now.

 

[Jiggz]

Great it seems the fuel delivery is OK but, you need to do a full test run at WOT with the cowl or engine cover off. While running at wot monitor the clear filter if it stays full and if the engine rpm is affected by the fuel delivery, i.e. if the clear filter gets empty does the engine starts to slow down or stutter? If the filter stays at least 1/2 full and the engine stutters, the problem could be with the float settings or sticky inlet needle or sticky float in the carb's bowl.

As for the green fluid pooling inside the carb air cover, that is fuel oil mix that overflowed when you tilted the engine all the way up and is normal. It is usually bluish in color depending on the type or brand of oil you use.

 

[Themanofsteel]

Ok got it. I'll try that next. Did you read my comment about the top spark not sparking?

 

[Jiggz]

Yes, I read if but only after my last response. So maybe your problem should be fixed after fixing that wire. Anyways, do a WOT test with while monitoring the clear fuel filter. Hopefully, you have found the fix to your problem.

 

[Themanofsteel]

What is a reed problem? What is the reed?