'77 25hp Fuel Pump

[Notaone]

Can anyone tell me the proper way to test the fuel pump on a 25 hp Johnson? I have removed the output line and it is pumping fuel but I don't know what is considered the correct amount. My main problem being that the motor bogs after 1/2 throttle when under load. Works great in a barrel both in and out of gear. I suspect my problem may be a coil breaking down(one is severely cracked), and have order replacements but thought I might check the pump while waiting for parts to arrive. Thanks for all responses.

 

[AlTn]

Re: '77 25hp Fuel Pump

if you had strong pulses from the fuel line while pulling the starter through, you've got enough...if they became weaker, or merely a dribble, that's a problem

 

[F_R]

Re: '77 25hp Fuel Pump

Can anyone tell me the proper way to test the fuel pump on a 25 hp Johnson? I have removed the output line and it is pumping fuel but I don't know what is considered the correct amount. My main problem being that the motor bogs after 1/2 throttle when under load. Works great in a barrel both in and out of gear. I suspect my problem may be a coil breaking down(one is severely cracked), and have order replacements but thought I might check the pump while waiting for parts to arrive. Thanks for all responses.

If you pump the squeezer bulb when it is bogging down, and that makes it take off again, it probably is the pump----OR an air leak somewhere between the pump and fuel level in the tank.

You asked if there is a "proper" way to test the fuel pump, and there is. Tee a fuel pump pressure gauge into the line between the pump and carburetor and monitor the pressure. Generally around 4psi at medium speed. But of course, the above squeezeer bulb test works just as well and is a lot cheaper.

 

[jasper60103]

Re: '77 25hp Fuel Pump

Can anyone tell me the proper way to test the fuel pump on a 25 hp Johnson? I have removed the output line and it is pumping fuel but I don't know what is considered the correct amount. My main problem being that the motor bogs after 1/2 throttle when under load. Works great in a barrel both in and out of gear. I suspect my problem may be a coil breaking down(one is severely cracked), and have order replacements but thought I might check the pump while waiting for parts to arrive. Thanks for all responses.

Just curious, which replacement coil did you go with?

edit: Also, have you figured out a way to push (or remove) the coil wire pin from the connector w/o the special tool?

 

[Notaone]

Re: '77 25hp Fuel Pump

I went with the Mallory coils. Knowing my luck, this is probably not the best choice, but hopefully it will be better than the cracked one. Will be interesting to see if the bogging is eliminated when I squeeze the fuel bulb. After 3 weeks of working on this boat and motor, I'm about ready to go back to my canoe

 

[Notaone]

Re: '77 25hp Fuel Pump

Regarding the special tool to remove the pin, I didn't even know one was required. The way you asked the question though I suspect you know the answer. If you do, I would very much appreciate you sharing your knowledge.

 

[jasper60103]

Re: '77 25hp Fuel Pump

Regarding the special tool to remove the pin, I didn't even know one was required. The way you asked the question though I suspect you know the answer. If you do, I would very much appreciate you sharing your knowledge.

No, I didn't mean to come across as a know it all. I just noticed it from reading my manual and hoping you could enlighten me. Maybe someone can share a little ingenuity here?

edit:
I suppose you could cut the wire and splice it back together, but I rather not do that.

The manual references three tools:
1. Insert tool OMC part# 322697
2. Pin remover OMC part# 322698
3. Socket remover OMC part# 322699

 

[AlTn]

Re: '77 25hp Fuel Pump

using rubbing alcohol as a lubricant I pushed them out with a piece of rod that was almost the same diameter...push them as far as you can then use some needle nose to pull them the rest of the way...the needle nose work for reinsertion as well...the tools are available from cdi ( possibly more suppliers as well ) they are kinda pricey tho'

 

[Notaone]

Re: '77 25hp Fuel Pump

That sounds like a good plan, and close to what I thought I would do after looking at the connectors after Jasper brought the subject up. Why do you use alcohol in lieu of grease?

 

[AlTn]

Re: '77 25hp Fuel Pump

that's from the oem manual for '78 9.9-15 hp manual...the alcohol will evaporate and the grease could magnify an already loose pin fit to the point the pin could get pushed back in the socket and not connect properly...that last part is from a plug in maf meter on a 1987 volvo..grease sounded good to me as well

 

[jasper60103]

Re: '77 25hp Fuel Pump

That sounds like a good plan, and close to what I thought I would do after looking at the connectors after Jasper brought the subject up. Why do you use alcohol in lieu of grease?

+2
Thanks!