1985 Johnson 25hp fuel issue

cvtech1

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I bought a 1985 Jon Boat with a 1985 25hp Johnson that has been serviced but still acts like it is starving for fuel. I discovered a leaking fuel quick disconnect at the tank, it then ran fine for a while then started the same cutting off at wide open throttle for no apparent reason. Can anyone help please?
 

kenmyfam

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Re: 1985 Johnson 25hp fuel issue

I bought a 1985 Jon Boat with a 1985 25hp Johnson that has been serviced but still acts like it is starving for fuel. I discovered a leaking fuel quick disconnect at the tank, it then ran fine for a while then started the same cutting off at wide open throttle for no apparent reason. Can anyone help please?

Squeeze bulb when it starts to falter and see if it picks up and runs O.K. again. If so you either have an air leak into the fuel line somewhere or the fuel pump is starting to fail.
 

cvtech1

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Re: 1985 Johnson 25hp fuel issue

Kenmyfam, the squeezing the bulb and pumping the choke would help at times but it seems to be helping less. How difficult to change the fuel pump? Thanks.
 

kenmyfam

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Re: 1985 Johnson 25hp fuel issue

Kenmyfam, the squeezing the bulb and pumping the choke would help at times but it seems to be helping less. How difficult to change the fuel pump? Thanks.

Pumping the "choke" will richen the available mixture, squeezing the bulb and you are acting as the pump yourself. It should run fine by squeezing the bulb if there are no other air intrusions anywhere. If the bulb squeezing is having little effect then I would consider rebuilding the carbs. Could be partially blocked jets and some gunky varnish like matter floating around in there.
 

cvtech1

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Re: 1985 Johnson 25hp fuel issue

The bulb doesn't stay really hard, should I replace the whole hose assembly first? Also how could I check the fuel pump to see if it is functioning properly? Thanks.
 

kenmyfam

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Re: 1985 Johnson 25hp fuel issue

The bulb doesn't stay really hard, should I replace the whole hose assembly first? Also how could I check the fuel pump to see if it is functioning properly? Thanks.

Bulb does not have to stay really hard.
Is it electric start ??
 

cvtech1

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Re: 1985 Johnson 25hp fuel issue

Ok thanks, anybody know to check fuel pump to tell if it is working properly?
 

kenmyfam

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Re: 1985 Johnson 25hp fuel issue

Ok thanks, anybody know to check fuel pump to tell if it is working properly?

That's one reason I asked if you had electric start.
Pull the pump to carb's hose off the pump.
Attach a length of hose from that outlet of the pump to a container.
Crank motor and see what comes from the hose to the container.

Regular strong spurts........all is well
Strong spurt to begin with and tapers off........fuel pump is failing.
Drips, next to nothing or nothing at all......pump is not working.

I always put any gas in the container into my truck.

Good Luck.
 

cvtech1

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Re: 1985 Johnson 25hp fuel issue

Kenmyfam, I missed the question I thought you said "it is electric start mis read. I will try this and get back with the answer soon. Thanks so much.
 

kenmyfam

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Re: 1985 Johnson 25hp fuel issue

Pull plug wires or lanyard so it does not try to fire up and put the muffs on to be on the safe side with your water pump. That is unless you are in the water already when you test it.
Good Luck.
 

cvtech1

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Re: 1985 Johnson 25hp fuel issue

I have not been able to get to the fuel pump yet, when it dries up a bit I will go test the pump and get back with you. Thanks again!
 

cvtech1

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Re: 1985 Johnson 25hp fuel issue

Well guys and kenmyfam, I gave up on trying to check the fuel issue I checked the lower unit and it had water coming out then oil. A mechanic said I needed seals and to service the lower unit. While at it He will give me a tune up get it running great. He checked compression and spark and all was fine. Is my lower unit still ok?
 

kenmyfam

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Re: 1985 Johnson 25hp fuel issue

Well guys and kenmyfam, I gave up on trying to check the fuel issue I checked the lower unit and it had water coming out then oil. A mechanic said I needed seals and to service the lower unit. While at it He will give me a tune up get it running great. He checked compression and spark and all was fine. Is my lower unit still ok?

If you have water in the lower unit then it could well be the seals all need replacing. It could however be as simple as needing a new nylon washer on the upper and lower plugs in the lower unit. NOTE, do not remove the phillips screw down there.
Keep a close eye to what the "mechanic" is doing to your motor and don't accept it back till you both give it a test run.
 

cvtech1

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Re: 1985 Johnson 25hp fuel issue

Thanks for the info. appreciate it. What is the problem with the phillips screw and should I run the motor kind of hard with the muffs to test?
 
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