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Jason, Marine Mechanic
Category: Boat
Satisfied Customers: 16209
Experience:  Degree in Marine Technology. Gas and diesel marine mechanic.
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I have an 1988 115 HP mercury motor that runs fine when I

Customer Question

I have an 1988 115 HP mercury motor that runs fine when I get it cranked up. When I am traving across the water at about 15 mph for about 20 minutes then When I slow to troll it tries to stall I can pull the throttle back to neutral and it will stay running only with some throttle But when I put back into gear, it will start to stall again It will only re start with a little choke, This has been going on for a while I had the carbs cleaned and the throttle adjusted and this hasn't solved the problem. I am thinking it is a fuel issue since it will run fine and then all of a sudden it will stall out I have tried both premium and standard fuel but its no difference. Is the motor getting to hot where it stalls the motor but why would it crank back up. Any help would be great
Submitted: 2 years ago.
Category: Boat
Expert:  Jason replied 2 years ago.

Hi Mark, my name is ***** ***** I will be helping you today. Once you get the engine running again after it stalls, if you throttle up will it then make full power?

Did you have the carbs professionally cleaned? Or did you do them yourself?

Customer: replied 2 years ago.
Expert:  Jason replied 2 years ago.

Did you see my other question? I wrote "Once you get the engine running again after it stalls, if you throttle up will it then make full power?"

Customer: replied 2 years ago.
No you have to try and gradually bring the throttle up or it stalls
Expert:  Jason replied 2 years ago.

But if you gradually bring it up, say do it slowly, can you eventually get back to full power?

Customer: replied 2 years ago.
Expert:  Jason replied 2 years ago.

That does sound still like a carburetion issue. Is there a fuel water separating filter mounted anyplace between the engine and fuel tank? The guy that did your carbs, I assumed you spoke with him about the issue. What has he told you?

Customer: replied 2 years ago.
No filter, I bought the boat last season and was told it had recently had a full overhaul including carbs
Expert:  Jason replied 2 years ago.

Good morning. Ahhh I gotcha. The engine needs 3 things to run. Compression, timed spark ignition, and the proper ratio of fuel to air. Your symptoms point to an issue with the fuel air ratio, and not a compression or ignition issue. (if you had compression or ignition problems you would have a huge lack of overall power).

On boats, carbs clog for 2 reasons. Either debris in the tank makes its way past the little engine mounted filter (which is as about as good as pantyhose). Or the fuel in the fuel/oil mix that sits in the carbs float boat evaporates when the engine is not in use, and the oil gets left behind. That oil forms a bit of a goo like substance that clog fuel jets. It doesn't take much clogging at all to effect the ratio, and the engine will start having symptoms of that, like the stalling. When I do carbs usually what I find is it's a combination of both, both evaporated petroleum leftovers and debris in the tank that has made it's way past the engine filter. Whenever I do carb jobs for my customers I always recommend adding a fuel/water separating filter to the boat. These filter down to 10 microns plus they catch water (where engine filters do not). And the filter kits run about 50 bucks, with replacement filters running about 10 bucks. Not 1 person ever has told me no, fix the carbs but do not add a filter. So if there is no filter on your boat I would have a doubt the carbs were ever done. In the grand scheme of the overall work it makes no sense not to add a filter.

On your engine it's a safe bet to have the carbs done. You don't have the symptoms of anything else other than carbs that are starting to clog up.

Expert:  Jason replied 2 years ago.

I think that should do it. But I work for tips so I do want to make sure you are happy with my service before you go. If you had a further question on the issue by all means feel free to ask. If not, Just in case you do not understand the way the website works (and some folks do not). You do have to put forth a positive rating in order for it to credit me for helping you. When ratings are not done, the website simply keeps your deposit and they will not credit me. The ratings box is located at the top of the screen. To rate, you must select the star you wish and also confirm it. Please let me know if you run into any problems or errors when trying to do it. If you do have a problem, or if you can not see the ratings box which is at the top of the screen. Please reply back "I rate Jason's service _______" and fill in the blank.

Questions do not close out, so if you have to come back later on with follow up questions to the issue you still can even after doing a rating.

Thank you

Expert:  Jason replied 2 years ago.

Hello, just checking in. The website has charged you but they have not credited me for helping you out because no rating has been put through yet. Did you have any further questions on the issue, was there anything else, or something I missed?