Fuel pump kit for old Johnson

[Swell]

I've been trying to find a service kit for my 1968 6hp seahorse fuel pump but no joy. It seems that the kit is not available.

Does anyone know which are the critical parts to replace and if it's possible to purchase those parts individually?

[Joe Reeves]

The most critical part has always been the diaphragm. To my knowledge, a kit is not available for that model and necessitates a replacement pump. Pump is part number 388685, most likely available on this site.

[F_R]

18-7350 fuel pump, buy it here at iboats.

OR

18-7823 repair kit, MIGHT fit. I can't guarantee that it will.

[Swell]

I suppose what I'm trying to do is avoid having to replace the whole unit which is quite pricey. Is it possible to purchase just the diaphragm from anywhere? Is it possible to just replace the diaphragm?

[Swell]

"18-7823 repair kit, MIGHT fit. I can't guarantee that it will."

I looked at that kit and it does look tantalisingly similar to the older pump shape! Has anyone tried it?

[Swell]

Did Johnson just make one 'Square' shaped fuel pump? If so, the newer kit should be ok.

[F_R]

See, that is the problem. The original Johnson pumps were not all alike on the inside. Sorry, I'm not smart enough to itemize the diffferences. Johnson said none of them were repairable, that is why they don't sell individual parts.

[Swell]

Ahhh - fair enough! My mind can rest now. I only wanted to service the pump so I could be sure it was ok - it's an old motor and the kits are cheap so it seemed to make sense. If a new assembly is the only option I'll only do that if absolutely necessary - they're not cheap. Is there an easy way of checking if the pump is healthy? It does pump fuel but I've only been able to test it at higher rpm - engine won't idle - so I'm not sure how efficiently it's working.

As I say, is there an easy way to test it with the pump removed from the power head? The whole thing is in pieces at the moment!

[Joe Reeves]

Pump the fuel primer bulb, acting as a manual fuel pump. If the engine still won't idle, the problem is not the fuel pump.

[tashasdaddy]

running a outboard service business, i have quit rebuilding most fuel pumps. labor and guarantee, new pump is cheaper on me.

[F_R]

Ahhh - fair enough! My mind can rest now. I only wanted to service the pump so I could be sure it was ok - it's an old motor and the kits are cheap so it seemed to make sense. If a new assembly is the only option I'll only do that if absolutely necessary - they're not cheap. Is there an easy way of checking if the pump is healthy? It does pump fuel but I've only been able to test it at higher rpm - engine won't idle - so I'm not sure how efficiently it's working.

As I say, is there an easy way to test it with the pump removed from the power head? The whole thing is in pieces at the moment!

Oh-oh. That last statement says a lot. For sure, it doesn't work now, no testing needed. You may need this:
http://www.sschapterpsa.com/rambling...g_fuelpump.htm

Those pumps won't work correctly if not assembled 100% correctly.

[Swell]

Pump the fuel primer bulb, acting as a manual fuel pump. If the engine still won't idle, the problem is not the fuel pump.

I'm not looking at the fuel pump as a potential reason for the lack of idle. As you say Joe, if the outboard is primed and the float chamber full, and it won't idle, then the fuel pump is not the culprit. It's just that because it won't idle, I can't test the performance of the fuel pump at idle speed. I’ve done this at higher rpm by removing the fuel inlet from the carburettor and checking that fuel is flowing out of the tube – which it is. I just can’t test that at idle speed, so I can’t be sure it’s pumping as it should at idle speed. Hence I’d like to be able to test it some other way if possible.

I’m basically trying to tick everything off the list before I re-assemble the motor. I’ve so far fixed a sheared cylinder head bolt, decarbed the pistons, replaced the impellor, overhauled the carburettor, checked the leaf valves and replaced the drive shaft seal. I’m also about to replace the whole set of ignition parts as the coils were the originals and completely shot – had to be replaced, so took the view that I might as well replace the points, condensers and wires at the same time.

I want this motor to work 100% so I don’t have to worry about it for a good while!

[Swell]

Oh-oh. That last statement says a lot. For sure, it doesn't work now, no testing needed. You may need this:
http://www.sschapterpsa.com/rambling...g_fuelpump.htm

Those pumps won't work correctly if not assembled 100% correctly.

My apologies - I meant that the powerhead is in pieces. Bad wording on my part! The fuel pump has just been removed by removing the 2 mounting screws but is intact otherwise.

That link is excellent by the way! Thanks. I'll test the fuel pump using the method described at the end which is the only test I've come across other than the method I've already used with the motor running.