83 Johnson gt 150 runs fine on muffs but nothing in the water

Solodad · Jun 23, 2013

I have a 1983 Johnson gt 150 (J150STLCTE)
The motor starts and idles fine on muffs, but when I get it in the water, NOTHING!
I've cleaned all three carbs and they seem to be working fine (jets are clear, floats are working properly). Could this be an air leak in the fuel lines? Should my inline fuel filter have air in it?

boobie · Jun 23, 2013

Re: 83 Johnson gt 150 runs fine on muffs but nothing in the water

Check the compression on it and then when it's running pull one spark plug lead at a time to see if that cyl is firing or not. On a good cyl you will get a drop in rpm.

Solodad · Jun 23, 2013

Re: 83 Johnson gt 150 runs fine on muffs but nothing in the water

I just got it out of the shop, having the lower unit rebuilt, and they said the compression was fine. Around 90 on all 6 cylinders, but I will check it again.
Thank you, and I will post what I come up with

emdsapmgr · Jun 24, 2013

Re: 83 Johnson gt 150 runs fine on muffs but nothing in the water

Agree with boobie, check your spark. That engine will seem to run just fine on the trailer when firing on 4 or 5 cyls. You need all 6 firing when the lower unit is buried under a foot of water and it's in gear.

Solodad · Jun 24, 2013

Re: 83 Johnson gt 150 runs fine on muffs but nothing in the water

Absolutely right...
No spark on the port side at all. I never thought to check it because I just replaces both power packs.
How world I check to see if the pack is getting the power it needs? Im very familiar with an electric meter. What are the odds of the brand new pack being bad?
Thanks guys!

Randy

Solodad · Aug 7, 2013

Re: 83 Johnson gt 150 runs fine on muffs but nothing in the water

Ok guys, I came up with the money for a new power pack, and it started right up. Ran about 30/60 seconds and went dead. Almost like it burned all the fuel out of the carb bowl?Now I can't get it to start at all. Tried a little starter fluid... I'm stuck!
Can ya help me?!! Please! :/

Solodad · Aug 7, 2013

Re: 83 Johnson gt 150 runs fine on muffs but nothing in the water

I've got the motor in a tank by the way. Not on muffs...

metriccrescentwrench · Aug 7, 2013

Re: 83 Johnson gt 150 runs fine on muffs but nothing in the water

First thing - don't use starting fluid, it'll rob the cylinders and bearings of lubrication and hasten your engine's demise.

Start with the basics. Re-check compression. Check spark with a variable gap spark tester set at about 7/16 inch. See if pumping the primer bulb will keep it running.

Solodad · Aug 7, 2013

Re: 83 Johnson gt 150 runs fine on muffs but nothing in the water

Okay it's firing on all six cylinders and runs fine on muffs (idling a little high). I tilt the motor down and it dies... it will not run in the tank any help will be greatly appreciated

Solodad · Aug 7, 2013

Re: 83 Johnson gt 150 runs fine on muffs but nothing in the water

I took the air intake off and fuel is pouring out of the carbs...
Won't run at all tilted down

emdsapmgr · Aug 7, 2013

Re: 83 Johnson gt 150 runs fine on muffs but nothing in the water

Does the engine have spark now?

Solodad · Aug 7, 2013

Re: 83 Johnson gt 150 runs fine on muffs but nothing in the water

Yes
All 6 are firing

boobie · Aug 7, 2013

Re: 83 Johnson gt 150 runs fine on muffs but nothing in the water

Sounds like the carbs are flooding.

Solodad · Aug 7, 2013

Re: 83 Johnson gt 150 runs fine on muffs but nothing in the water

That's what I'm thinking...
Why all 3?

Solodad · Aug 7, 2013

Re: 83 Johnson gt 150 runs fine on muffs but nothing in the water

That's what I'm thinking...
Why? Why all 3?
The floats and valves are working properly

83 Johnson gt 150 runs fine on muffs but nothing in the water

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