1973 Johnson 6hp need help

[Michael leblanc]

I just got a 1973 Johnson 6hp ran awesome but wasn't getting fuel so I rebuilt the fuel pump and put it back on started it up and it was running ok and it was getting fuel but when I rev it up it seems like it is straining to build up rpms ...never did this before hope someone can help me out

 

[oldcatamount]

Re: 1973 Johnson 6hp need help

I'd suggest a spark test first. Get an "air gap" spark tester and set it for 7/16". The ignition spark should jump that 7/16" and be bright blue. If it tests good on both cylinders, do a compression test. (you can do that without a compression tester by slowly pulling out the starter cord and feeling the two resistance spots through the cord). If it "feels" the same, it should be ok. Of course, the best thing to do is to get a compression tester and get accurate results but, I'm cheap, and I don't recommend buying stuff you may not need. If those two things test ok then, the carb is probably dirty inside and will require a carb kit and thorough cleaning. But start with the ignition test first and be sure you have the correct spark plugs and the gap is .030.

 

[Willyclay]

Re: 1973 Johnson 6hp need help

Welcome to the iboats.com forum! The members here are great and the experts, which I am not, can help you with any question about that great old motor. Member oldcat has you started with some good advice. Try the link below for aqdditional info about this series motor that also has pictures. I have the factory manual for your motor and should be able to provide specific info as needed. Good luck!

Johnson

 

[kbait]

Re: 1973 Johnson 6hp need help

Agree w/Oldcat.. but on those points motors, 1/4" snappy spark will suffice. 7/16" for CD ignitions..

Also, did you try pumping the primer bulb when it's 'straining'? If it helps, you may have a fuel line leak somewhere, or faulty fuel pump.

Check link/sync (ignition advance sync'd w/throttle valve).. Just search that term in this forum.. you'll get great info.

Check out the machinist's 6hp link: Johnson He's a wizard!!

Good luck!!

 

[Michael leblanc]

Re: 1973 Johnson 6hp need help

Thanks y'all I will check it out when I get off work ...I just put brand new j6c spark plugs they had j4j in it before would that matter and when I put fuel pump back together they only had 1 spring in the kit and they picture shows 2 But I put it together anyway would that be the problem cause it ran awesome the day before yesterday

 

[kbait]

Re: 1973 Johnson 6hp need help

If you keep priming it and it runs fine, then suspect the fuel pump. J6C plugs are fine... if you've got proper spark to 'em.

 

[Michael leblanc]

Re: 1973 Johnson 6hp need help

Thanks for your time man I appreciate it I should be getting off at 2 today so I'll check it put and let u know

 

[Willyclay]

Re: 1973 Johnson 6hp need help

when I put fuel pump back together they only had 1 spring in the kit and they picture shows 2

Springs? I don't see any springs in the diagram: Johnson Fuel Pump Parts for 1973 6hp 6R73S Outboard Motor

 

[Michael leblanc]

Re: 1973 Johnson 6hp need help

Yea there's a sping inside the diaphragm in the middle and there suppost to be a smaller one on the inside too but I didn't get it when I order it

 

[oldcatamount]

Re: 1973 Johnson 6hp need help

Willy, there's a light spring (or two) inside the pump. They come with the re-build kit and resemble the coil spring inside a ball point pen (only smaller).
P.S. the first part of my email address is "olgeezer"

 

[Michael leblanc]

Re: 1973 Johnson 6hp need help

It revs up but just takes longer then it did the day before idk I'll mess with it this afternoon and let y'all know

 

[Willyclay]

Re: 1973 Johnson 6hp need help

Good to know! I was headed to the garage to pull out my service manual. You guys are the greatest resource around.

 

[Crosbyman]

Re: 1973 Johnson 6hp need help

Rebuilding the OMC Fuel Pump

2 springs in the pump and 2 mushroom head on top of springs

me.. I dab the bases of each spring with crazy glue and glue then to the mating plastic nipples and then dab the top of each spring with same glue and glue the white plastic mushrooms on the spring ends before attempting to assembles the diaphragms ... makes things much easier
READ READ READ ASSEMBLY INTRUCTIONS AND DO A BLOW TEST

 

[Michael leblanc]

Re: 1973 Johnson 6hp need help

Yeah I put everything back together right just didn't put little spring in it ...I did a blow test but had to blow kinda hard threw the end that sucks from tank and it made a rattle noise and the air came out the other end and I blew on other end and nothing came out so everything was right just no little spring ...I just got home and put motor in tank and started it right up no choke and it ran fine just don't know if it will mess up the pump without spring

 

[Michael leblanc]

Re: 1973 Johnson 6hp need help

To me it just seems like maybe it's not getting enough fuel at first till I rev it up and it sucks hard from pump and open the diaphragm inside....just thinking out loud cause I did have to blow kinda hard until the air came out...i don't know just throwing that out there

 

[Michael leblanc]

Re: 1973 Johnson 6hp need help

Just found out the little spring is called the air-dome spring ....so maybe it's staying collapsed till I rev it up and it sucks hard to let fuel threw....any other ideas ...lol sorry for keep posting but I'm just so nervous to go ride in the swamps of louisiana

 

[nwcove]

Re: 1973 Johnson 6hp need help

what were the results of the spark and compression tests? does it work any better if you squeeze the primer bulb when it bogs?

 

[Michael leblanc]

Re: 1973 Johnson 6hp need help

I didn't mess with it long just showed my neighbor what it was doing cause I had to go get kids at day care and go somewhere so tomorrow when I get off work I'll mess with it for a while and try spark and pump ball to see what it does and I will let y'all know

 

[Willyclay]

Re: 1973 Johnson 6hp need help

To me it just seems like maybe it's not getting enough fuel at first till I rev it up and it sucks hard from pump and open the diaphragm inside....just thinking out loud cause I did have to blow kinda hard until the air came out...i don't know just throwing that out there

Maybe this link will help: Rebuilding the OMC Fuel Pump

 

[Michael leblanc]

Re: 1973 Johnson 6hp need help

Yes that's the link I used to put it back together ...thanks for helping just didn't have the little air dome springto put in it cause the guy forgot to put it in kit but I talk to him last night and he is mailing it to me now ...thanks though hope that's what it is