Johnson 9.9 hp fuel pump/fuel tank prob? New Fuel pump solved problem

[sharboat]

I have a 1974 Johnson 9.9 hp motor that I have either a fuel pump or
fuel tank problem. I need help determining weather I have a fuel pump
or fuel tank/line problem. Here is what I have tried so far:
1. Took fuel line off at carberator and gravity fed fuel/oil mixture
in via a small 1 quart plastic container. Motor starts easy and
runs great. This tells me the carberator is OK.
2. Cleaned out fuel tank and rinsed with fresh gas and then put in
new gas with 50:1 two cycle oil mix.
3. open air valve on tank, pump up fuel bulb till solid feel, pull out
choke, gear in neutral, set throttle at start position.
4. Start motor with a couple of pulls and runs for about 30 sec and
sometimes I can get to run longer by pumping fuel bulb while
motor is running.
5. Got Johnson fuel pump repair kit and replaced output pump diaphragm,
large spring, and plastic end cap between spring and diaphragm.
Rest of fuel pump parts look OK. I think I replaced the small spring
and plastic end cap but not real sure as I do not have an assembly
drawing. If some one can send me a fuel pump assembly diagram
I would appreciate. This repair so far has not helped running problem.
6. Checked out fuel line and fuel bulb and could not find any leaks, it
looks in good condition. If I take the fuel line off at fuel pump
input and squeeze fuel bulb I get a good flow of gas.
7. I would appreciate any help toward solving this problem.

 

[Daviet]

Re: Johnson 9.9 hp fuel pump/fuel tank prob?

Re: Johnson 9.9 hp fuel pump/fuel tank prob?

If you remove the line from the pump to the carb and pull engine over several times, do you get good pulses of fuel out of line? Is the gasket between fuel pump and block in good shape.

 

[sharboat]

Re: Johnson 9.9 hp fuel pump/fuel tank prob?

Re: Johnson 9.9 hp fuel pump/fuel tank prob?

I will try your suggestion to remove line to carb and check for fuel pump
output when truning motor over. Yes the fuel pump gasket to motor is
new and bolts are tightened.

 

[Rick.]

Re: Johnson 9.9 hp fuel pump/fuel tank prob?

Re: Johnson 9.9 hp fuel pump/fuel tank prob?

I would guess that little temporary fuel bottle you made up was being held higher than the motor? If so it didn't need the pump to work as it was being gravity fed with fuel. If it wasn't higher then it could be your tank screen is plugged but a 9.9 should run longer than 30 seconds on a bowl of gas. The other thing that comes to mind is where is your tank when running it in a barrel? I always place my tank on a stool or bench so the pump doesn't have to lift the gas all the way from the floor to the pump. Here is a link (the only one I know of ) that tells how to do a re-build on the fuel pump. There is also just a whole bunch of good information on the 9.9 that should be of interest to you. Best of luck. Rick.
http://www.sschapterpsa.com/ramblings/OMC/OMC info.htm

 

[sharboat]

Re: Johnson 9.9 hp fuel pump/fuel tank prob?

Re: Johnson 9.9 hp fuel pump/fuel tank prob?

I have the motor on my boat in the water and tank is sitting on bottom of
boat probably about 18" below the motor. Tank and bulb seem ok, I can
take line off going into fuel pump and when I squeeze fuel bulb I get
a nice flow of gas out of fuel line.

I tried taking the fuel line off at carb input and then pumped fuel bulb
several times and then pulled starter cord and no fuel came out of
fuel line out of fuel pump. I have replaced the main diaphram in fuel
pump without any change. I have full rebuild kit for fuel pump but
would like to see a diagram of fuel pump so I make sure I get it
back together properly.

 

[Rick.]

Re: Johnson 9.9 hp fuel pump/fuel tank prob?

Re: Johnson 9.9 hp fuel pump/fuel tank prob?

http://www.sschapterpsa.com/ramblings/Rebuilding_fuelpump.htm
Did you look at this? Rick.

 

[jay mendoza]

Re: Johnson 9.9 hp fuel pump/fuel tank prob?

Re: Johnson 9.9 hp fuel pump/fuel tank prob?

That is the best instructions sheet out there, I used it quite successfully, had good results. A little lithium grease helped me keep the springs w/ plastic caps in place during assembly. I also scored a mark down the side of the pump plates before I took it apart.
In case anyone is interested, a good working fuel pump will lift the fuel over 4 feet; as my tank is on the ground, and my engine on a tall stand running in a trash can full of water with no problems.

 

[sharboat]

Re: Johnson 9.9 hp fuel pump/fuel tank prob?

Re: Johnson 9.9 hp fuel pump/fuel tank prob?

Yes I copied the rebuild instructions and will finish rebuilding fuel pump
and report on results. Thanks, Dan

 

[sharboat]

Re: Johnson 9.9 hp fuel pump/fuel tank prob?

Re: Johnson 9.9 hp fuel pump/fuel tank prob?

Rebuilt fuel pump according to the OMC instructions but fuel pump still
does not work. I tested the valves in the valve housing and they both
leak thus no fuel pump action.

Does anyone know if I can buy the valve housing by itself or do I have
to buy a complete new fuel pump?

 

[sharboat]

Re: Johnson 9.9 hp fuel pump/fuel tank prob?

Re: Johnson 9.9 hp fuel pump/fuel tank prob?

After rebuilding fuel pump still did not work properly. Examined the two
tiny valves on center plate of fuel pump and they were leaky.

Bought a new Sierra fuel pump from iboats for $44 and now boat
motor runs like new. Great power and idles down nicely.

 

[Rick.]

Re: Johnson 9.9 hp fuel pump/fuel tank prob? New Fuel pump solved problem

Glad to hear it all worked out for you. Have fun. Rick.