Johnson gas tank.

[Bream Killer]

I found one of these at a yard sale a few years ago for $10.00. It looked like it had been used maybe one or two times and was clean as a pin inside and out. I hadn't used the boat all this time and you guys had been helping me thru the re-build of the 9.5 Johnson. The motor is running OK except every now and then its starved for fuel and a quick pump of the bulb and it's back in business. The issue is it's intermittent. I did a complete rebuild of the carb and put a new fuel pump on it. On the new fuel pump it was thicker than the old one. I had to get longer screws to mount it. It was like it had an extra section in it.
Thinking it could be the gas tank vent I cracked the fuel tank top and it still did it one time. I haven't been on the open water yet, just running in the tank. Is there anything to be concerned about this old tank? It seems to be in great working order, nice and tight, no leaks.

 

[flyingscott]

Those are very good tanks. That is a nice find.

 

[havoc_squad]

Put a low pressure fuel/vacuum gauge T inline before the primer bulb with the in-line part going to the . Then install the low pressure fuel/vacuum gauge. Making sure it is snug so it does not allow air to be pulled in.

I think you can break one of those gauges with the primer bulb pressure if you apply too much pressure, so it is best either to prime the carbs safely before putting the gauge on or put it before the primer bulb.

First see if you have more than 4 inches of mercury vacuum at any time. If you do you have something blocking/restricting your fuel flow.

If you have less than 4 inches of mercury vacuum, then you next need to check for air bubbles in fuel line while the motor is running.

See if you can get the appropriate sized fuel rated clear hose and put it between the outboard motor fuel inlet and the fuel pump.

If you at any time see air bubbles in the fuel line, you have a hose or fitting issue or your fuel tank inlet is sucking air.

If the tank is full enough to not suck air, the biggest issue is fuel hose clamps/zip ties that do not seal the fitting from pulling in air.

Yes, it is possible to have a fuel line suck air but not leak fuel out that is not fully secured.

 

[oldboat1]

Think I would borrow another line and bulb and try that. Squirt a little lube in the tank vent to make sure it works smoothly and opens completely.

 

[racerone]

See the 2 wee pin on the fitting where you plug in the hose.----One is a vent valve.----The other let fuel out.---If one pin sticks out further than the other replace O-rings on those valves.----These tanks are much better that the plastic junk offered today.

 

[gm280]

The mere fact that when you squeeze the primer bulb and that keeps running, tells me you are not venting the tank properly OR your fuel pump isn't working correctly. I would pull the fuel line off, after the fuel pump, and verify it is indeed working before doing anything else.

If it is pumping correctly, then it has to be the vent of the tank. That type tank vents when you plug on the fuel line to the engine. If it isn't venting doing that, it starves for fuel. So make sure that is working at the tank connections as well.

A very easy what to prove that is remove the gas cap when you test it and see if it still starves for fuel. If it still starves for fuel that way, you either have the primer bulb on backwards or the fuel line is restricted with something inside of it... JMHO!