Sport jet 120 wot at 3800 rpm will not plane.

[jerryjerry05]

#2 from the top? Then check the gasket.
#2 from the bottom? then check the fuel pump.

Get 4 spark testers. Only 7-8$ each.
Hook them up and start the motor.
See if all work when you try to accelerate.

 

[Naliahs]

How can I tell if the gasket is broken or if there is water in the cylinder? There is good compression on all the cylinders.

 

[Naliahs]

Also plug numbering is top to bottom

 

[Naliahs]

So I just got a scope cam and looked at the cylinders and all look new!!!, reed valves appear normal but honestly I would not know what I should look for. They all look uniform. I want to saw when I pulled the plugs they were soaked in gas. Can the carbs be an issue? Should I soak the carbs?

 

[jerryjerry05]

IF your getting 3800 I doubt the carbs are the problem unless the floats are set wrong
or the jets clogged?

You test all cyl for fire?

Just did a job on a 90 3cyl. Mercury.
Wouldn't get past 1500
The float on the bottom carb, set wrong.
The fuel pump was a new rebuild. Done WRONG.

Job on a 115 Mercury wouldn't get past 2500
The bottom carb, the jet was full of crud about a gram of crud blocking the hole in the jet.

When you cleaned the carb, did you make sure the jet was clear?

A piece of dirt the size of a pin head can block the jet.
Inline filter?

Test all cyl. for fire.
Install an inline filter between the pump and the carbs.
Clean the carbs, paying attention to the jets.
Starting fluid test? Start the motor, spray SF around the intake side.
Everywhere but the throat of the carbs.
If it makes any difference? then it's sucking air

 

[Naliahs]

I am going to look at the carbs now.

 

[Naliahs]

When rebuilding the carbs does the gasket between the engine and carb need any gasket sealant or oil?

 

[jerryjerry05]

No sealer on that gasket.

You do the tests I recommended?

(

Test all cyl. for fire.​

Install an inline filter between the pump and the carbs.​

Clean the carbs, paying attention to the jets.​

Starting fluid test? Start the motor, spray SF around the intake side.​

Everywhere but the throat of the carbs.​

If it makes any difference? then it's sucking air?)​

 

[Naliahs]

Ok so cleaned the carbs soaked them and sprayed the jets everything looked good. Put it all back together and got new spark plugs. Same problem persists. Seems only the bottom two cylinders are working and the top two are not. Can the high jets be completely clogged? I turned the engine over and saw very little fuel on the top two cylinders. Also when the engine running unplugging plug 1 and 2 makes no difference. I fact running a little better. Examined all reed valves and they all look good. At this point I am assuming it’s the carburetor. Can it be the coil pack?

 

[Naliahs]

Bump

 

[jerryjerry05]

You've only got 1 carb for 2 cyl. each carb has only 1 jet for both cyl.
You have 2 separate systems, 1 carb and 1 pack for the 2 top and 2 bottom.

Does it have spark on all 4 cyl.??

Sprayed the jets?? how?
You need to physically poke a pin through the hole in the jet.
But your getting 3800 so I doubt the carbs clogged, but make sure anyway.

The drop to 3800 shows a cyl. that's not firing.

You do the test we've suggested?

You need to get spark testers for all 4 cyl.
Install and go for a ride. post the results.

Compression #s?

Try swapping packs around and see if the spark changes?

Do the test we suggested and post the results.

 

[jeffreykujawa@windstream.]

Naliahs,
Your issue you originally posted sounds exactly the same as the one I am currently experiencing with my 1996 Sea Rayder F16 with Sport Jet 120. Did you ever figure out what the issue was?

 

[GA_Boater]

Naliahs,
Your issue you originally posted sounds exactly the same as the one I am currently experiencing with my 1996 Sea Rayder F16 with Sport Jet 120. Did you ever figure out what the issue was?

The OP has not visited since shortly after starting this thread a year ago. Start your own thread,

Closed.