1985 Johnson 70HP VRO fuel pump

[cchinchak]

How do I check to make sure the VRO fuel pump is working properly?
The VRO system on this motor has been disabled and now using 50:1 pre-mix.
Using the primer bulb, I can pump fuel through the filter and out the top of the the fuel pump. After I pumped the bulb, I hooked a clear hose to the top nipple of the fuel pump and cranked the engine for about 10 seconds. About one ounce of fuel came out while cranking the engine. Should there be more or less fuel flowing out? Is there a better test?
I bought this boat/motor last summer and the first time I took it out, the engine would die when I tried to increase the speed. It would idle fine. I checked the spark and got 1/2 inch arc. The cylinder compressions were 105, 101, and 101. Now I just want to rule out the fuel pump before overhauling and cleaning the carbs. Thanks for your help.
Chris

 

[tashasdaddy]

Re: 1985 Johnson 70HP VRO fuel pump

do the carbs, special attention to the jets, you need # 317002 tool to remove jets, or make one. are you using the old fuel side of the vro pump, or did you go with a straight fuel pump?
when you get it running, i would do a decarb, and see if it brings the compression up.

Decarb, take a can of seafoam put 3/4 of it in the gas tank, with only 1 gallon of premixed gas. put the rest in a spray bottle. start the engine, and let it come up to temperature. then remove plugs, and them some real good shot of seafoam into the cylinders, replace plugs, let sit 15 minutes. restart, and spray the rest of the seafoam into the carbs, so the the motor almost stalls, wait and repeat until the seafoam is gone.then take for a wide open spin. then put in new plugs, ad premixed gas to the tank, and take it for a wide open throttle spin. it is going to smoke like a house on fire, during this process.

afterwards compression.recheck

 

[cchinchak]

Re: 1985 Johnson 70HP VRO fuel pump

It has the old VRO pump, but I dont know if it is working properly. I want to rule out the fuel pump before going to the carbs. thanks.

 

[jtexas]

Re: 1985 Johnson 70HP VRO fuel pump

rule out fuel pump: pump the primer bulb while attempting to accelerate. If perfomance does not improve, fuel pump is not at fault.