Johnson 150 runs fine with Motor flusher will not run when in water

[imported_LittletB99]

I've got the weirdest problem, my bass boat with a Johnson Gt 150 runs fine whenever I've got the motor flusher hooked up to it and testing it in the driveway but whenever I get it out on the lake it will just die whenever I give it any throttle. The boat set for 5 years, I've rebuilt the carbs, replaced one bad powerpack, plugs and wires and gas filters. I've tested with a portable gas tank to rule out stuck anti-siphon valves. Whenever I've got the boat on the water, the water pump appears to be working because water is coming out of the back of motor while the boat is idleing when it is in the water or whenever it has the motor flushers hooked up. Thanks for any advise.

 

[JB]

Re: Johnson 150 runs fine with Motor flusher will not run when in water

Two main suspects, LittletB99.

Not making power with all cylinders. With no load that engine can sound "fine" on 2 cylinders. Testing with no load is not really testing.

What happens if you squirt some premix fuel (never starter fluid) into the carb throats when she tries to stall? If she picks up you just fed a bad carb.

What happens to idle speed if you disable each spark plug, one at a time? Does idle speed drop for each cylinder, or do some make no difference? A cylinder that makes no difference is making no power.

Inadequate fuel supply: What happens if you pump the primer bulb when it tries to stall? If she picks up you have a fuel supply restriction or a bad fuel pump.

Let us know what you find, and good luck.

 

[R.Johnson]

Re: Johnson 150 runs fine with Motor flusher will not run when in water

On an outboard engine, alway's start with a compression, and spark test. Then a squeese pottle of pre-mix for the carb's. Save's alot of time, and money

 

[mikesea]

Re: Johnson 150 runs fine with Motor flusher will not run when in water

Wow,this must be the week for 150 problems, last week was 70's.be sure to check out the posts for the 150 rebuild that has stalling probs. Many of us are baffled there. As for your engne.You rebuilt the carbs, BUT ,did you soak them in cleaner making sure all the jets and passages are clean.Have you done a spark and compression test on the engine.You could have stuck rings.Just having spark doesnt mean its strong spark.You should change the impeller,if it sat for 5 yrs.It's BAD.No question.Just because it pumps,dont mean a thing,its bad and will probably start falling apart in short time.But that has nothing to do with your engine running poorly at this time.

 

[imported_LittletB99]

Re: Johnson 150 runs fine with Motor flusher will not run when in water

Where can I get a compression tester at, how much do they cost or is it just cheaper to take it somewhere and have the test ran?

Thanks again

 

[F_R]

Re: Johnson 150 runs fine with Motor flusher will not run when in water

Any auto parts store, Harbor Freight, Sears, Maybe Wal Mart, Some of them are pretty cheap. Get the kind that screws into the spark plug hole so you don't need three hands. But check to make sure you have enough room between the plug hole and cowling first.

 

[imported_LittletB99]

Re: Johnson 150 runs fine with Motor flusher will not run when in water

I've got good compression on all cylinders, haven't gotten impeller changed yet but will probably tomorrow, whenever I pull a plug wire on any cylinder it does start to miss.

Forgot to mention that sometimes the primer bulb starts to collapse after the boat has been running. I had taken the boat to a shop before this post and they weren't getting good spark on the left 3 cylinders and the boat was missing pretty badly so they replaced the power pack on that side and then the missing went away.

The shop said the primer bulb problem was probably due to the anti-siphon valve in the tank but I've connected a portable tank to the motor to eliminate that as the problem. After replacing the primer bulb twice I no longer have that problem but I cannot keep it running in the water long enough to even determine if the problem exist. Whatever is causing this just seems to keep getting worse.

I'll check the carbs with pre-mix in the morning. Thanks to everyone for all advise.

JB, I see you are a fellow Muskie Hunter, it's what we call Rocktober at Cave Run Lake here in KY now. That's where I hope to get by Sunday. Some big fish have been caught this week.

 

[mikesea]

Re: Johnson 150 runs fine with Motor flusher will not run when in water

Have you tried squeezing the primer ball as you throttle up ,to force more fuel to the carbs. I'm hinking your fuel pump dried out during lay up. do you have VRO or do you have fuel pumps and mix gas,with oil.Another thing I learned the hard way years back,A v-6 engine may not get enough fuel from a portable fuel tank that is for a small 2 cylinder engine.

 

[imported_LittletB99]

Re: Johnson 150 runs fine with Motor flusher will not run when in water

Mike,

I've tried squeezing the primer ball and that hasn't helped a bit. It does have the VRO on it. I disassembled the VRO or I think that's what I disassembled, (where the oil and gas mix) and checked the diaphrams. I did find that the small oil filter was really dirty and I cleaned it but that didn't help any.

Thanks again,

 

[firemann2003]

Re: Johnson 150 runs fine with Motor flusher will not run when in water

I feel your pain with your 150, mine has had me pulling my hair out for few months. Copy and paste this into your address bar (http://forums.iboats.com/bbBoard.cgi?a=viewthread;fid=28;gtid=1179302). It is my latests post and maybe there are some things that can help you to.

Just remember one thing about this forum, these guys know thier stuff, so make sure to give as much info as you can and follow the advice to the letter. If you do that you will have it running like new in no time.

 

[tashasdaddy]

Re: Johnson 150 runs fine with Motor flusher will not run when in water

what were your compression reading. good tells is nothing.

 

[itwontletmein]

Re: Johnson 150 runs fine with Motor flusher will not run when in water

this is what i found when mine did this you didn't say what year but i had a filter that screwd in the front were fuel line came in looked like a cone the o ring was shot and it was sucking air ran great with no load as soon as i gave it gas it would die i have a manual 4 a 96 if it will work u can have it shoot me a email j-and-a@justice.com

 

[imported_LittletB99]

Re: Johnson 150 runs fine with Motor flusher will not run when in water

Ok guys, I took carbs apart again and double checked everything, replaced a couple plug wires, made sure all connections were tight, took the boat out again and it would get to about 40 MPH and then just sort of bog down, if I let back on the throttle a little then it picks back up. It's like it is getting flooded or something now. This is how my original problem started.

Compression
between 80-85 on all cylinders.

Whenever I unplug a plug wire on any cylinder it does begin to cough and sputter.

Pumping the primerbulb helps none. Als0 the primerbulb is no longer collapsing since I replaced it with an OMC brand bulb rather than on I got a Walmart.

Anyone with any clues why it would just cut out? Could I have a vaccume leak or could it be sucking air? That's what I first thought it was whenever the bulb was collapsing but like I said that problem went away after I put a good bulb on it.

Thanks for any input you might have.