Fuel problems on 1982 Johnson 70

[david brum]

Hi all

Thanks everyone for the excellent advice I've gotten so far. This is an unbelievable resource.

I recently rebuilt my carbs and fuel pump ( this was after the motor failed to start on an overnight camping trip. Four hours back on the kicker. Lucky for me the weather was good and the girls brought their knitting).

The original symptoms were starting up OK, then dieing when shifing into gear. After a few minutes it died altogether and wouldn't start at all. It was leaking fuel out of the front of the carb cover.

I did a rebuilt and just tried to start her yesterday (after fixing a puzzling electrical problem). She doesn't want to start. The primer bulb won't get solidly firm and I can see fuel leaking through the vents in the lower unit.

I am wondering if this is a symptom of a float not seated properly? I also installed an inline fuel filter from the auto parts store. Would that be causing trouble? Something more serious? I'm all ears!

 

[tashasdaddy]

Re: Fuel problems on 1982 Johnson 70

sounds like the floats are out of adjustment. did you use rebuild kits?

 

[david brum]

Re: Fuel problems on 1982 Johnson 70

I did use rebuild kits and adjusted the floats as per the directions that came with the rebuild kits. That doesn't mean I did it correctly though. The kits did not come with new floats, but I installed new pivots pins, seats, etc.

I think the floats needed to be set at 3/4" fully open. Does that sound right?

Thanks very much for the help!

BTW, the top carb is open a hair when the choke solenoid closes. Would that have any effect?

 

[david brum]

Re: Fuel problems on 1982 Johnson 70

sounds like the floats are out of adjustment. did you use rebuild kits?

I'm now pretty sure I set the floats correctly. I'll try to take them apart again tomorrow to check though. Is there anything else I should look for while I'm in there? I'm so close to getting her back on the water I can taste it. Just in time for silver salmon too.

Also, is it OK to add an inline fuel filter? The filter is clear plastic, and I can see that it doesn't fill all the way with fuel, although maybe that's because fuel is flowing out of the carbs.

 

[david brum]

Re: Fuel problems on 1982 Johnson 70

OK guys, I opened up the carbs again and checked the floats. They are all set correctly, according to the spec on the sheet that came with the rebuild kits. I am still getting gas spilling down the lower unit leg when I pump the bulb. Now I'm wondering what I should check next. I can't visually see gas leaking around any gaskets, but can hear a swish behind the carbs when I pump the bulbs.

A couple of questions:

1) Where is the gas coming from, i.e. how does it spill out of the block?

2)Can I check the carbs with air pressure to see if the needles are working properly?

3)Could this mean a bad head gasket or similar?

Sorry for the newbie questions. I am determined to fix this thing myself and it's a steep learning curve, for sure.

 

[Big Bubba]

Re: Fuel problems on 1982 Johnson 70

David Brum,
Yeah, I was just reading your thread and after reading it I was thinking maybe your fule pump has went bad. Reason I say this is there is a rubber diaphram that uses the pulse pressure from #2 piston or the middle cylinder to make the diaphram pulse thus pump fule to the carbs as the engine is running. Maybe that rubber diaphram inside of the fuel pump is torn and when you pump the fuel bulb up your pumping fuel into the pulse line from the fule pump into #2 cylinder where it feeds from and maybe from there it goes down the lower unit from there. I would remove that rubber pulse line from where it goes into the block on #2 cylinder from the fuel pump and then use a container to catch the fuel if any should come out, it should not though, and if it does then that is your problem and that is what is causing your issues yoru having in the first place. Let us know what you find and if this caused the issue or not. Take care, Bob

 

[Big Bubba]

Re: Fuel problems on 1982 Johnson 70

David Brum,
Double check your fuel pump. I re-read your post and it said you rebuilt the fuel pump. Did you put it together right? If not maybe that is what is causing the issue. I am not trying to say you did a terrible job rebuilding the fuel pump but maybe you didn't do something right. But do as I said and take the rubber pulse line off from the block side and stick that one end of the rubber pulse line into a container and give the bulb a squeeze and see if fuel comes out of that rubber pulse hose and if it does then that is what is wrong. There should be NO FUEL comming out of that rubber Fuel pulse hose going to the engine block but there should be fuel going to the carbs for the other line going to the carbs. Let us know I am curious. Take care, Bob

 

[Big Bubba]

Re: Fuel problems on 1982 Johnson 70

David Brum,
One more question for you. I own a 1983 year, 70 horse power, Johnson like yours and am having Bogging/Stalling issues whenever I go from idle/nuetral to forward throttle. Are you having issues like that with your 70? Yeah, I have my 70 Johnson mounted on a 20 foot Pontoon Boat and absolutely love it except for the bogging issue. I am going through my carbs again since I missed one of the orifices when I cleaned them last so I am hoping that is my issue and I will be doing a link and sync verification afterwards and hopefully that will solve my issue. Let us know how you make out with your issue. Take Care, Bob

 

[Big Bubba]

Re: Fuel problems on 1982 Johnson 70

David Brum,
One more thing make sure you don't havet he fuel lines going to the wrong place, like the main fule line swapped going to the #2 cylinder port versus going to the carbs and vice versa. Never know the easiest things are what gets us sometimes so double check your fule lines a re going to the right place from the fuel pump.

 

[david brum]

Re: Fuel problems on 1982 Johnson 70

Bubba, you are a genius. I, however am a bonehead. It turned out that I had switched the hoses and was filling the crankcase with gas. It got so full that the flywheel wouldn't turn.
I almost let the magic smoke out of the starter before I realized what the problem was.

I took out the bottom spark plug and fuel kind of glugged out. After that, the starter worked fine. A bunch of fuel sprayed out the spark plug hole as I ran the starter. Good thing I don't smoke.

After a few tries, she fired up and ran at idle just fine. I can't believe I screwed up such a basic thing, especially since I had to take apart the carbs three time to try to figure out what I might have done wrong. I also replaced the battery cables because I thought the starter wasn't working.

Thanks so much for helping me figure this out. This really is an unbelievable resource.

 

[Big Bubba]

Re: Fuel problems on 1982 Johnson 70

David Brum,
I am glad I was able to help you out. After reading, re-reading your post I got to thinking that maybe the fuel pump was not put together correctly or that you had the rubber lines coming from the fuel pump going in wrong directions. When you said you were getting fuel coming down the lower leg unit then that turned on the light bulb for me so glad it is working for you now. Yeah, Like I said I am having a stalling/bogging issue on my 70 horsepower and like a bonehead myself I missed 1 out of the 3 total jets when I cleaned the carbs out so I will be going back through my carbs religously and make sure I clean every passageway and make sure I get all three not just two jets out and claen them really good. I would highly suggest you invest in a OMC service manaul specific to your outboard I have but haven't had the time to look at it yet becuase I am currently deployed in the military but boy next year I plan on making up for all the boating and camping in 2010, I will be home the end of Janaury 2010 for sure. Take care of yourself, Bob

 

[david brum]

Re: Fuel problems on 1982 Johnson 70

Hi again Bob,

Yeah, I did have a stalling problem with my motor before I rebuilt the carbs. I'll try to get it on the water this week to see if the rebuild solved it. I also missed the upper jets when I did the rebuild. They are kind of hidden. I only noticed them because I was wondering why there were so many left over washers in the rebuild kit.

My motor has been good until the fuel system gave me trouble on the last trip. The previous owner really neglected it, so I'm steadily working my way through the major wear points. Given how neglected it was, I'm really imnpressed that it ran so well. So far this Summer I've had to:
- replace the trim motor (ordeal involving drilling out the 3/4" pin)
- rewire the entire boat
- replace the battery cables
- rebuild the water pump, fuel pump, carbs

Here's hoping that it will be trouble-free for a while.

BTW, if you're currently deployed in the Middle East, I wish you a safe deployment and swift return the the US.

Thanks again for the insight!

Best wishes,
David