86 Johnson 150 V6 - Won't start with trim up. . .won't idle

[Kymatlo]

If I put the trim up at all, the motor won't start. Gets a good crank, won't get gas. When I trim it all the way down, it starts, but blows smoke.

It also won't stay idling unless I rev the idle control constantly. It idles really rough even then. If I'm idling, and I put the trim up (trailering, shallow water) it dies every time.

Seems to run fairly strong at speed, but has a vibration during takeoff. Once I wind it out and run it 2-3 minutes, vibration stops and it runs fine.

I feel like the engine is flooding when I put the trim up without giving it throttle. Is this a possiblity? Would oil/fuel mix be a problem (it's oil-injected)? What do I check and where should I look? Thanks

 

[ezeke]

Re: 86 Johnson 150 V6 - Won't start with trim up. . .won't idle

The floats in the float bowls at the bottom of each carburetor are designed to close the fuel off once the float bowl is full. Then the engine pulls fuel from the bowls until the floats drops low enough to open the valves and let in more fuel.

Tilting the engine raises the float and closes off the valve so that fuel will not continue to enter the bowl.

The motor is not designed to be run in the Tilt mode. The trim mode is only 15º. In trim mode it should be OK, in tilt it is not.

 

[Kymatlo]

Re: 86 Johnson 150 V6 - Won't start with trim up. . .won't idle

Thanks for yor response

I understand that the motor isn't made to run with the tilt up. . .that's not my problem. As I stated in my original post, the motor won't run with the trim up. It won't start even if the trim is up only a few degrees. It litterally has to be ALL THE WAY down, so that the motor is flat against the mounts along the transom, in order to get it started.

I think you may be on to something with these float bowls in the carbs though. Are they going to be fairly obvious to find? How should I test their functionality? Maybe they are loose and closing prematurely, or the floats are fluttering open/closed (causing the rough idle). Any ideas on inspecting/testing these floats?

 

[ezeke]

Re: 86 Johnson 150 V6 - Won't start with trim up. . .won't idle

Once you have the carburetors off, it is not very difficult to clean them and rebuild. If you have a manual it will help a lot.

If you are willing to remove them, many shops will do them for you for relatively little money, including the kits.

There is a short video on line somewhere, maybe someone knows the link.

 

[Solittle]

Re: 86 Johnson 150 V6 - Won't start with trim up. . .won't idle

It is time to rebuild the carbs. Get the OMC manual for your engine if you don't already have one and have at it.

 

[kenmyfam]

Re: 86 Johnson 150 V6 - Won't start with trim up. . .won't idle

Manual is a must !!!

 

[Kymatlo]

Re: 86 Johnson 150 V6 - Won't start with trim up. . .won't idle

I've got the Clymer and it has a pretty good schematic and instructions on dissassembly and cleaning.

Of course, yesterday my truck starting overheating so now I've got to play with that before I worry about the boat. . .it's always something. Hopefully I can get the carbs off next week sometime and clean them out. Thanks for the advice.

 

[Kymatlo]

Re: 86 Johnson 150 V6 - Won't start with trim up. . .won't idle

Thanks everyone for your responses and advice.

I cleaned the carbs out Saturday afternoon. They were mucked up and the floats were not functioning. I sprayed with carb cleaner, worked them around a little, sprayed some more. . . so and so forth. Got them cleaned up.

Took the boat out Sunday morning. Started on the first turn of the key, idled smooth as silk, and ran 52MPH fully loaded with two people in it.

Problem solved! Thanks again.