1974 15 HP Johnson problems

[gtmgooser]

Guys, I purchased this motor about a month ago and I'm having some problems keeping it running. I can get it started and all is fine but after running for about 100 yards I loose fuel line pressure and the motor dies. I then pump the fuel line bubble, get line presure again, start it and it runs for about another 100 yards and quits again. What the heck can possibly be going on here? The fuel line is new and it has a new 6.6 gallon plastic tank. I have tried adjusting the relief valve (little screw on top of filler cap) in several positions and just can't seem to figure it out.

I would really appreciate any assistance in correcting this condition.

[Burksee]

Is the bulb collapsing or is it just getting soft? If the bulb is collapsing it could be bulb it self or the pickup in the bottom of the tank. If not it sound like you've gotta fuel pump issue. Give us some more information when you get a chance! Good Luck!

[Big Frank 25]

Check the fuel line under cover for cracks. Look near the clamps.

[gtmgooser]

After the motor stops running, the bulb is soft because its empty it but its not sucked together or collapsed. As for cracking in the line, wouldn't I see moisture (fuel) around any line cracks? Finally, for the the fuel pump, is that expensive to have replaced?... this is my first boat motor so pelase excuse the ignorance.

[Burksee]

After the motor stops running, the bulb is soft because its empty it but its not sucked together or collapsed. As for cracking in the line, wouldn't I see moisture (fuel) around any line cracks? Finally, for the the fuel pump, is that expensive to have replaced?... this is my first boat motor so pelase excuse the ignorance.If the bulb is soft I suspect the problem is between the tank and fuel pump. I've seen those multi layer hose's collapse internaly. If its stiff or show's signs of kinking I'd replace it. From inside the motor cover, where the fuel line connects I'd be looking for cracks in the hose's from there to fuel pump. I'm not sure but I believe the fuel pump on this one is vacuum operated, check the hose from the pump to the motor. If all looks good your more than likely looking at a worn and tired pump. They're not bad to rebuild, a couple of diaphams and some hose. Take your time, clean everything and dry with carb spray and dont overtighen any go of the bolts/screws! They dont have to be "reefed on" tight! ;)

[dtg]

I had a similar problem with an 86 15hp, only it would occasionally NOT start for X minutes. Sometimes it would run flawlesly I found out that my fuel pump was bad. Of course the carb got rebuilt before that was found.

[outdoorsman69]

Will it continue to run wide open? can you squeeze the bulb and keep it running at idle? if you can do this probably fuel pump. If not could be a problem in the carb. fuel pump about $50. 2 hoses, 2 screws pretty simple fix.

DCG

[TONGA]

yea it sounds like your fuel pump is not keeping up.you either have a 3 or a 2 line fuel pump (don't remember off the top of my head) but you can tell be looking at it,just follow your fuel line from where it comes into the motor to the fuel pump and see if it has 2 or 3 lines hooked to it. if it is a 3 line then you have the supply hose coming to it then a output hose that runs to the carb and a vac line that runs into the block. if the vac line is bad your pump will not keep up and it will not leak fuel..if you have a 2 line pump it will just have the supply line and the output line running to the carb that pump will get it's vac from a port in the block behind the pump,there is a gasket between the fuel pump and the port in the block if this gasket leaks your pump will not keep up and she will not leak fuel...I don't imagine you have any test equipment so I think the proper course of action for you would be to replace all the lines under the cover (and gasket behind the pump if so equiped) (a few $)and see if it dose not clear up the problem if it dose not then I would say that fuel pump is suspect.

[DangerDan]

Check the connection where it plugs into the fitting on your OB. (it's plastic?) I had the same problem once. Run your tiller to one side, then the other. Does it put that fitting in a bind pulling? What happened with me is the fitting lost its seal where it was pressed together. I saw a few drops of gas drip and the film on the water. Until then I was at my witts end as to what the problem might be. good luck!

[dtg]

Will it continue to run wide open? can you squeeze the bulb and keep it running at idle? if you can do this probably fuel pump. If not could be a problem in the carb. fuel pump about $50. 2 hoses, 2 screws pretty simple fix.

DCG
Mine wouldn't even idle, it would just die in a matter of seconds, sometimes it would start and sometimes it wouldn't. There was something in the fuel pump that came loose and would block it. We checked the spark(ok) compressioon(125 ea) rebuilt carb again(was done last Oct) and fianlly the fuel pump and it now runs like a new motor.

Please keep this thread updated as I'm curious about the solution!!!!

[gtmgooser]

Thanks guys... I really appreciate all the insight. I am going to work on it this weekend and I'll report back on what I find.

Thanks again,
George

[252Life]

I'll be following this one too cause I had the same problem tonight. 115 OMC sea drive, hasn't been run since mid July. Last time I ran it was when I did the sea foam in the carbs to clean out the carbon build up...after that it was purring like a kitten. Now I go to start it tonight and can't even get a cough. The ball doesn't get hard when I pump it (tried explaining that one to my wife :yikes: ) and it stays deflated. Not a hint of gas fumes coming from the fuel pump area or anywhere in the engine for that matter.

[gtmgooser]

Well, I replaced the fuel pump after checking all the other suggestion and it appears as though that was the problem. I put the muffs on it and ran it in the yard for about 15 minutes with no problems. Guess the real test will come this weekend when I put it back in the water to see how it runs with resistance against it.

Thanks again for all the input.
George

[dtg]

Thanks for following up on this!!!! I'll bet she'll run just fine this weekend. I know mine will because of all the other stuff we did before finally figuring out it was the fuel pump.
Good luck and don't forget the oars!!!!! Oh and stay close to the launch at first.

[StumpJumper]

Well, I replaced the fuel pump after checking all the other suggestion and it appears as though that was the problem. I put the muffs on it and ran it in the yard for about 15 minutes with no problems. Guess the real test will come this weekend when I put it back in the water to see how it runs with resistance against it.

Thanks again for all the input.
George

You shouldn't run it that long out of water dude... Get a plastic 55gal drum and saw it in half, fill it with water.

[dtg]

You shouldn't run it that long out of water dude... Get a plastic 55gal drum and saw it in half, fill it with water.
He said he had the water muffs on it. As long as water is coming out of the "pee hole" on the outboard he should be alright.....unless you know something I don't?