Sudden loss of power

[j.a.g]

Hey guys, I have a 1989 Searay Seville with a 4.3 liter merc and a merc alpha 1 outdrive. This issue is hard to explain on a computer but, towards the end of last summer the boat would start to cut out after being driven for a while. I thought that it might have water in the fuel so I installed a fuel/water separator but that did not help. It doesn't really sputter like I think that it would if there was water in the fuel. I am starting to think that it could have something to do with the distributor. I am just not sure how to trouble shoot the problem. Any help would be great.

Thanks

 

[sutor623]

Re: Sudden loss of power

Hey guys, I have a 1989 Searay Seville with a 4.3 liter merc and a merc alpha 1 outdrive. This issue is hard to explain on a computer but, towards the end of last summer the boat would start to cut out after being driven for a while. I thought that it might have water in the fuel so I installed a fuel/water separator but that did not help. It doesn't really sputter like I think that it would if there was water in the fuel. I am starting to think that it could have something to do with the distributor. I am just not sure how to trouble shoot the problem. Any help would be great.

Thanks

Google CDI troubleshooting manual and pick the proper link for your motor. It sounds like an ignition issue, I think you are right.

 

[j.a.g]

Re: Sudden loss of power

I am having trouble finding the CDI troubleshooting manual for my engine. What does CDI stand for?

 

[Don S]

Re: Sudden loss of power

sutor623 seems to thing all engines work like outboards, and they don't. CDI doesn't have any info for IO's

After you changed the fuel filter, did you look at the contents of the old filter to see if it was full of water? If it was, you may have a new filter and a carb that is full of water.
When was the last full tuneup on your engine? Spark plugs, cap and rotor. You should also do a compression test.

Here is where you find troubleshooting for your engine http://boatinfo.no/lib/mercruiser/manuals/mercruiser7.html#/0

 

[sutor623]

Re: Sudden loss of power

CDI doesn't have any info for IO's

Here is where you find troubleshooting for your engine http://boatinfo.no/lib/mercruiser/manuals/mercruiser7.html#/0

Word.

 

[Don S]

Re: Sudden loss of power

Word.

What does that mean?

 

[Pete104]

Re: Sudden loss of power

I don't know either. I tried loading that link & had no success! Perhaps that's what he referring too!

 

[sutor623]

Re: Sudden loss of power

What does that mean?

Hahha, well obviously I know little about IO motors So Im going to sit this one out and soak it in. Word, as in gotcha, or okay, or good to know. Slang term of the younger generations.

 

[sutor623]

Re: Sudden loss of power

I don't know either. I tried loading that link & had no success! Perhaps that's what he referring too!

Hmmm, link pulled right up for me.....

 

[H60Chopperdr]

Re: Sudden loss of power

You need to check your fuel tank for water. When under way the attitude of the boat changes. A globule of water can "roll" its way to the fuel pickup and kill the motor. The filter cannot transform water to fuel so you essential starve the motor. Does it restart soon after? If so, that is because the flat attitude of the boat "rolls" the water away from the pickup and you get clean fuel again. I agree with Don S. You should dump the contents of the fuel filter/separator into a clear container and look for water.

 

[j.a.g]

Re: Sudden loss of power

The boat never actually loses power. The filter that I have on has a drain on it and every time I have emptied it it seemed like it was just fuel coming out.

 

[mpdive]

Re: Sudden loss of power

Best thing to do is differentiate between an ignition or fuel delivery problem. When it's acting up you could physically see if it's starving for fuel or run the boat off a remote can. Have you replaced all the filters? Could even be an anti siphon valve, but again you need to determine fuel or ignition.

 

[H60Chopperdr]

Re: Sudden loss of power

The boat never actually loses power. The filter that I have on has a drain on it and every time I have emptied it it seemed like it was just fuel coming out.

I don't understand. Your original post says the engine "cuts out". How is that not losing power? When I had water in my fuel the motor would periodically just die out, not sputter out. When that blob of water finds its way to the pickup you are pulling pure water and no fuel filter can correct that. A fuel/water seperator has its limitations.

 

[H60Chopperdr]

Re: Sudden loss of power

One other thing...assuming this is carbureted, does it only die out at higher speeds? If so, you fuel delivery is not pumping enough fuel. You are good until the float bowl runs dry. It may idle all day long but once you pull rpm you have a limited amount of time until it starves. Inadequate fuel pressure can cause this as can a clogged carb orifice.

 

[j.a.g]

Re: Sudden loss of power

I don't understand. Your original post says the engine "cuts out". How is that not losing power? When I had water in my fuel the motor would periodically just die out, not sputter out. When that blob of water finds its way to the pickup you are pulling pure water and no fuel filter can correct that. A fuel/water seperator has its limitations.

I guess I used the wrong words. The engine doesn't die I just get a sudden loss of power then the boat regains its power. I had this same type of power loss feeling in a car that I had and it was the coil that went bad.

 

[H60Chopperdr]

Re: Sudden loss of power

From what you describe I would concentrate on fuel delivery first. I am in doubt of this being a spark issue. Good luck.

 

[Bondo]

Re: Sudden loss of power

I guess I used the wrong words. The engine doesn't die I just get a sudden loss of power then the boat regains its power. I had this same type of power loss feeling in a car that I had and it was the coil that went bad.

Ayuh,.... Let's atleast figure out what you've got,....

A 4.3l,.... Carbed,..?? 2bbl., or 4bbl,..??

Thunderbolt IV ignition,..??

Has it ever had a Tune Up,..??