baja mercury 120hp sport jet

[unhappycamper]

I have a 1995 baja mercury sport jet boat that has recently had all four pistons replaced and cyclinder bored out. It will run perfectly on land but dies when put in water. When in the water it will start but then will die out when given the throttle. I am new to boating so I'm looking for some possible problems. Timing was just done. In the water when started and given throttle it dies and afterward you can hear a bit of air being released. Thats all i have.

 

[unhappycamper]

baja mercury 120hp sport jet allergic to water

baja mercury 120hp sport jet allergic to water

I have a 1995 mercury sportjet. It has recently had all pistions and rings replaced + all four cyclinders bored out. It starts fine out of the water but starts and dies when in the water. It sounds perfect out but dies when given throttle in the water. The engine was recently timed. Hope for some needed advice to what may be causing my grief.

 

[foodfisher]

Re: baja mercury 120hp sport jet allergic to water

Re: baja mercury 120hp sport jet allergic to water

Idle speed, in gear, in water, too low.

 

[JB]

Re: baja mercury 120hp sport jet allergic to water

Re: baja mercury 120hp sport jet allergic to water

Is that a Mercury or a Force?? They are not the same thing.

 

[unhappycamper]

Re: baja mercury 120hp sport jet allergic to water

Re: baja mercury 120hp sport jet allergic to water

mercury

 

[CharlieB]

Re: baja mercury 120hp sport jet allergic to water

Re: baja mercury 120hp sport jet allergic to water

Hopefully during the rebuild the carbs were also cleaned, it is possible that the idle mixtures were not adjusted rich enough.

Idle mixture MUST BE adjusted while IN-THE-WATER to best idle speed PLUS about another 1/8 turn out to provide the additional fuel necessary for crisp acceleration.

Try turning each idle mixture screw out 1/4 turn and retest. Once running on the water fine tune the idle mixture as above.

 

[JB]

Re: baja mercury 120hp sport jet allergic to water

Re: baja mercury 120hp sport jet allergic to water

You get one thread, in one place, per topic, camper. I will merge your double threads, and strongly recommend that you read our rules.

 

[79Merc80]

Re: baja mercury 120hp sport jet allergic to water

Re: baja mercury 120hp sport jet allergic to water

mercury

Actually it is a Force powerhead, Mercury never had a 120hp powerhead

 

[unhappycamper]

Re: baja mercury 120hp sport jet allergic to water

Re: baja mercury 120hp sport jet allergic to water

We believe there is an exhaust issue. We put it in the water with the intake water hose off and it ran perfectly. We connected it and it died in about 20 seconds. We took it out of the water and it ran fine. We did a few other tests tonight. We took the engine out an ran a hose through the manifold. The water ran through the bellow and bottom perfectly. We than thought that there might be a blockage in the bottom of the jet drive. We took the bottom of the jet drive off and realized this could of been the problem. There was no seal. Our theory is that too much sea water is allowed into the exhaust sea water chamber and not allowing the engine to release its exhaust after the chamber is filled. We will replace the jet plate and make sure of a proper seal and put the engine back in. We'll let you know how it goes by Friday. I'm new to this forum and boating and really appreciate all your replies.

 

[unhappycamper]

Re: baja mercury 120hp sport jet allergic to water

Re: baja mercury 120hp sport jet allergic to water

The fly wheel cover says mercury!

 

[79Merc80]

Re: baja mercury 120hp sport jet allergic to water

Re: baja mercury 120hp sport jet allergic to water

Naturally it says Mercury, Mercury (Brunswick) owns Both Mercury and Bayliner (Bayliner owned Force/Chrysler). I have talked to several marine mechanics and they LOVED Chrysler/Force engines as they always needed worked on. But the fact remains the Force/Chrysler are NOT Mercury outboard engines.