1989 Mercruiser 4.3L (Alpha One?) - Engine cuts at high RPM

[kibitzer]

Hello Everyone-

I bought a 1989 Sea Ray Seville. It has a Mercruiser 4.3L engine (I believe it is the Alpha One) in it.

The boat has been running great for a month or so. I generally keep it in the river, but took it out onto the ocean for the first time a week or so ago and these problems started ... Note the day that I took it out, the sea was rough and the boat took a bit of a beating. (Up and down, jumping waves, etc).

The problem is that when I throttle all the way up as soon as the engine gets to almost max speed, it cuts out. If I pull back on the throttle, it recovers and drives fine. If I don't pull back on the throttle, it will drop down to an idle, then try to catch back up, then once it gets back up, it will do the same thing. Some times it will even stall out.

It almost feels like it is not getting enough fuel to fuel it when I'm opening her up. I am wondering if perhaps when I took it out on the bigger waves and did some jumps that maybe something got caught in the fuel filter, or something (maybe debris that was at the bottom of the tank) and is restricting full flow to the engine.

The other night the problem actually happened at a lot lower speed/RPM. I was taking off, put her to about 1/2 way (which has never given me a problem) and she kept cutting in and out as if she wasn't getting any fuel. I pushed the throttle back and forth a few times then she seemed fine and I could run her at about 75% throttle the way home.

Also one note, I don't know if it is relevant or not, but it seems that the problem happens more often when I am under a half tank of fuel. There are many times when the fuel tank is 100% full that it seems I see the problem a lot less. Another note is that the gas cap had a thin rubber gasket on it that broke (just was worn). I'm not sure if this could be causing the problem too? (ie, does it need to be pressurized?)

I've searched like crazy to see the "little" things that I look at first in order to diagnose/fix, and the only things I have found was change the fuel filter and that there is supposedly some sort of screen filter that is on the fuel line connected to the carb. I'm not a mechanic, but if I knew where the fuel filter was, and how to change it, I could change it out myself. I can't even locate it! I'm also not sure where that screen filter is located.

Any help at what you may think the problem is, and what I could do to resolve it would be awesome! I have been living with the problem, but as of the other night when it acted up even at low RPM I got nervous. I don't have a lot of money handy so taking it to a mechanic is unfortunately not an option

Thanks very much in advance.

 

[xltier]

Re: 1989 Mercruiser 4.3L (Alpha One?) - Engine cuts at high RPM

where the fuel line enters the carb is a bigger fitting that takes a 1 inch wrench.the screen is in there.theres a spring in there to so be a3ware of orientation.also check your anti-syphon valve at the tank fitting.

 

[ChrisCraftJohnny]

Re: 1989 Mercruiser 4.3L (Alpha One?) - Engine cuts at high RPM

Replace the carb filter as mentioned.

Replace the Merc Water/Fuel seperator filter mounted on Starboard side of engine. Use a common oil filter wrench.

When you take out the old seperator, dump out the contents into a bucket. If there is more than a tablespoon of water in with gas....

You have too much water in the gas tank. You then must remove the water from the tank.

Don S. states you do not have to drain the tank completely, just enough to get the water out.

Me, I would set up a few 5 gallon gas tanks for lawn mowers and such and pump out the old fuel using a fuel line connected to the output of the pump. That is, if your pump is electric. If not, you will have to use a pump that is rated for gasoline and pump out the tank.

Johnny

 

[kibitzer]

Re: 1989 Mercruiser 4.3L (Alpha One?) - Engine cuts at high RPM

Thank you guys very much, I will be doing this tomorrow morning the instant the sun comes up!

I need to get the parts. I've changed a few other things on the boat, and so far NAPA has had everything that I need. One guy told me it was the same engine as a 1989 Chevy Blazer.

I'm wondering for the parts, what do I ask for at NAPA to get a new filter .. the screen type that is in the carb? (What is it called, that won't make them laugh at me ... hehe, its easier to get laughed at online!). Also, when picking up the new fuel filter / water separator, if I just tell them it is for my boat, they should be able to locate the proper one, or is there anything else that I need to say to them in order to get the right parts?

Thanks so much!

 

[6meter]

Re: 1989 Mercruiser 4.3L (Alpha One?) - Engine cuts at high RPM

Well, by now they are either laughing at you or no parts yet. Drain the oil filter type water seperator filter first. In a glass jar to see if you have water in it. Napa should be able to match the parts. Get a screen carb filter, not a paper one. Actually you could just clean the old one if its a screen type. If you find very little water there, chances are you could need your carb overhauled. But by the sounds of expertise there, I would leave that to the pros. Good luck.

 

[kibitzer]

Re: 1989 Mercruiser 4.3L (Alpha One?) - Engine cuts at high RPM

I just want to take the time to say Thank You to everyone that posted. I am happy to report the problem has been solved and the boat is running really well!

In case anyone has the same problems as me in the future:

I replaced the carb inlet screen filter. It was very easy to do! 1/4 of this filter was filled with debris...

The boat did not have a fuel filter / water separator in it, only a fuel filter. I opened it up, and brought it to the marine store. The man said that he didn't think the filter had ever been changed, or at least in a very long time, because it had an old "stone" type filter in it. It was never properly installed either, as the spring was jammed into the stone horizontally, and caused it to crack right down the middle (Explains the debris in the carb filter, it was coming from this ancient stone-type filter). Replaced the fuel filter as well.

She doesn't hesitate one bit now and runs like a champ! THANKS AGAIN EVERYONE