1975 Johnson 25 hp fuel pump question

carltonwebb

Cadet
Joined
Jun 24, 2013
Messages
7
I have a new to me johnson 25 hp model 25e75b. I bought this from a guy who swore by it that has treated me well after I had another outboard die.

Anyway, this is my first post and I read through the archives but did not see anything related to what I am wondering. I am a fairly decent truck/equipment mechanic but ignorant to outboard motors. I am on vacation and the boat is in a tidal creek. I cannot get it loaded back without the motor after dragging it 300 miles. It also was a big part of my plans for the week.

Here goes. I put this on the boat and it got to where it would hardly run on saturday. I took the screen filter apart at fuel pump and found a sandy like substance in it. I realized that the liner had come out of the gray fuel line and clogged up the screen. I cleaned everything up and replaced the lines with rubber fuel injection lines and the motor ran pretty good. Then, I broke the drive/shear pin for the prop and had to wait until today to get 1 or 7 in my case.

So now, when i prime the bulb, I get a fuel spit from the back of the fuel pump at the mounting gasket to the side of the engine. Somewhere in the back part of the fuel pump anyway. I think it is bad if it does that ? and maybe it will explain why the boat will only run for about 200 feet unless u constantly give the fuel pump a squeeze. I have a clear inline fuel filter on the suction side of the bulb and I can see it run out and also the clear line from the pump to the carb seems to empty as well. It also has a tendency to stay smoky while running.

If it spits fuel in that back part of the pump, is that a busted diaprahm and if so, are the parts only available as an assembly? Any help would be appreciated. I only get 1 week a year off and it ends friday. All I want to do is cruise this creek and shrimp and spend time with my son before we have to go back to the daily grind.
 

Will Bark

Lieutenant
Joined
Aug 1, 2010
Messages
1,470
Re: 1975 Johnson 25 hp fuel pump question

Yes, that fuel pump has gone south on you; either get a rebuild kit or a whole new pump. If you are going to rebuild look up Leeroy's Ramblings he has a good picturoial on rebuilds even if it is for 9.9/15s. Good luck
 

bonzoscott

Senior Chief Petty Officer
Joined
Jul 26, 2008
Messages
745
Re: 1975 Johnson 25 hp fuel pump question

Welcome to Iboats! Don't torque any of the 4 screws too hard, can crack plastic body.
 

carltonwebb

Cadet
Joined
Jun 24, 2013
Messages
7
Re: 1975 Johnson 25 hp fuel pump question

Thanks guys..That seems to be it. I was only able to buy a whole assembly locally ($100). However, even online, I was not able to find a kit for that particular pump.It was $89 for the site that I could find the exact part # for online but could not find it on iboat. Now, it runs without cutting off and the smoke is almost null.

I opened the old pump and there was a small tear in the back diaphram of it.

If anyone has any suggestions on a prop, that would be next question. I have a really wide lowe 14 foot flat bottom jon boat. Its older so I cannot tell you the exact model number but the rails are 5 ft apart side to side. I will have to take the prop back off to find the current size/pitch.

In reverse & idle, the motor revs up nice and high. In forward, it moves the boat but not easily by any means. I can see where the throttle linkage is for the piece under the flywheel and it is full stroke as well as I took the rod and tried to give more and could not get anymore. It just seems to be that much load. I also adjusted the manual tilt some (one hole at a time) but did not help any. It will get me through this week and then I can address this. I had a yamaha 15 hp and it would move the boat a little better but I wanted a little more so when the Yamaha died, I got the 25 hp johnson.

Any suggestions?
 

Will Bark

Lieutenant
Joined
Aug 1, 2010
Messages
1,470
Re: 1975 Johnson 25 hp fuel pump question

You probably need to post this in the prop forum, they will have gurus there also. Good luck
 

carltonwebb

Cadet
Joined
Jun 24, 2013
Messages
7
Re: 1975 Johnson 25 hp fuel pump question

It also must have had a cylinder down as well. I cleaned the contacts on the plug wires this morning and replaced plugs and it has a lot more power. I could not find a champion j6c but got one for the time being in another brand and it helped immensely.
 
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