1997 150 Oceanrunner no combustion cylinders 1 and 5

[Coosaguy]

I have a 1997 Johnson 150 Oceanrunner that I’ve noticed isn’t reaching maximum running RPM, only getting to about 4500, checked for spark, fuel, compression and all are present.

I found that two cylinders have no combustion when I was doing the compression check. I pulled the plugs on cylinders 1 and 5 and found that the plugs still looked brand new. They had fuel on them but they did not show signs of use. Put in and old plug and left the new one connected to the spark plug wire and started the motor. Spark is present on both plugs.

I’ve also tried disabling the shift interrupter switch and moving coil packs around. Compression check was also good. All cylinders within 5 psi of one another.

Im new to marine engine maintenance and 2 stroke maintenance so any help would be appreciated.

 

[Bosunsmate]

If they had proper spark they should have no fuel on them even if its out of time.
You need to check spark can jump a 7/16 gap. You can make a homemade tester with a bit of wood and nails 7/16 apart.
PS always have the HT leads grounded when doing these tests, a ht wire just hanging off the engine can cause component damage

 

[Chris1956]

Each cylinder has it's own carb. For fun, loosen the bolt at the base of the carb bowl and see that fuel runs out of carb 1 and 5. I would be surprised if you don't have fuel in the carb, but you need to check.

 

[Coosaguy]

Each cylinder has it's own carb. For fun, loosen the bolt at the base of the carb bowl and see that fuel runs out of carb 1 and 5. I would be surprised if you don't have fuel in the carb, but you need to check.

so with the motor shut down, if i loosen that bottom bolt and the bowl has fuel in it thats a bad thing? Sorry if I'm slow on the pick up like i said earlier new to marine engines. I had thought of a possibility that i might be getting too much fuel in those cylinders but i didn't know how to check.

The bolt you are saying to loosen is it #19 in this diagram?

 

[Coosaguy]

If they had proper spark they should have no fuel on them even if its out of time.
You need to check spark can jump a 7/16 gap. You can make a homemade tester with a bit of wood and nails 7/16 apart.
PS always have the HT leads grounded when doing these tests, a ht wire just hanging off the engine can cause component damage

So I need to verify that the spark is strong enough to jump a 7/16 gap then? the more and more i think about it, it seems its going to be a Power pack issue or a fuel issue.

 

[Coosaguy]

Each cylinder has it's own carb. For fun, loosen the bolt at the base of the carb bowl and see that fuel runs out of carb 1 and 5. I would be surprised if you don't have fuel in the carb, but you need to check.

So I drained the carb bowls last night. The ones for cylinders 1 and 5 were the only ones that had NO fuel drain from them. The other 4 drained a good amount.

 

[Chris1956]

Well, that is a problem, as all carbs need fuel to run. If I remember, there is a screen between the throttle body and carb bowl. Maybe that is clogged?

Give the carb bowls a soft rap with the handle of a screwdriver and pump the primer and see if fuel flow returns to them.

If not, time to get carb kits and remove and clean the carbs. Use new gaskets and fuel inlet and needle, and you may need new floats as well.

As factory service manual can help you through the repair. The carb bowls are plastic, so check them for warping. The edge of the bowls warp, and a strait edge will reveal it.

 

[racerone]

A dry float bowl is certainly a problem.----No fuel going into those 2 cylinders means NO OIL also.----I suggest inspecting every carburetor and fuel line on this motor.

 

[Coosaguy]

Well, that is a problem, as all carbs need fuel to run. If I remember, there is a screen between the throttle body and carb bowl. Maybe that is clogged?

Give the carb bowls a soft rap with the handle of a screwdriver and pump the primer and see if fuel flow returns to them.

If not, time to get carb kits and remove and clean the carbs. Use new gaskets and fuel inlet and needle, and you may need new floats as well.

As factory service manual can help you through the repair. The carb bowls are plastic, so check them for warping. The edge of the bowls warp, and a strait edge will reveal it.

Only thing I don’t understand is the spark plugs for these cylinders had fuel on them when I pulled them. Maybe its not giving enough fuel. In any case I’ll order some rebuild kits and update after completion

 

[Bosunsmate]

Only thing I don’t understand is the spark plugs for these cylinders had fuel on them when I pulled them. Maybe its not giving enough fuel. In any case I’ll order some rebuild kits and update after completion

yeah i dont get that either. If you have proper spark that should of burnt off. Maybe its two issues

 

[Coosaguy]

yeah i dont get that either. If you have proper spark that should of burnt off. Maybe its two issues

hopefully the carb rebuilds i do will fix the issue if not then i'm gonna have to start looking into a power pack most likely. I've already swapped around coil packs and changed plug wires

 

[Coosaguy]

So I took apart the carbs for cylinders 1 and 5 and found the float bowls both warped and cracked on the side. Inside I found the float valve (pin that rides on the float with a spring) seized up from a massive build up of trash. had to take a pair of pliers to it to pull it out. So that may have been the issue. Waiting on new float bowls to arrive now. Will update again once its all back together.

 

[jakedaawg]

Dont forget to get the jets out of the old bowls...

 

[Chris1956]

You are going to clean all carbs, right? If two have excessive trash in them, I expect the others to be close behind...

 

[Coosaguy]

You are going to clean all carbs, right? If two have excessive trash in them, I expect the others to be close behind...

oh yeah for sure. I'm only changing these 2 for now to see if it resolves the issue i was having with these 2 cylinders. If so then I will order all the parts i need to clean out the other 4. If not then I will continue looking into the issue and clean those other 4 when i have it fixed. Regardless the boat wont be back on the water until the issue is resolved and all 6 cylinders have their Carbs rebuilt.

 

[Coosaguy]

Dont forget to get the jets out of the old bowls...

glad you said something about that. I had to go dig the old ones out of the trash

 

[Faztbullet]

And don't put the plastic washer under the seat....

 

[Coosaguy]

So the final update on this issue. The float valve being clogged was the cause of it all. Runs on all 6 cylinders and I'm getting around 5400-5500 RPMs at max throttle. Thanks for everyone's advice and help.