120 VRO Fuel Pump Help

[chuckb]

Last season my 1990 Johnson 120 VRO was experiencing fuel stavation problems. Died at mid to high throttle. I've attacked all the usual suspects (new lnes, filters, water spearator, anto-siphon, fresh fuel, etc, etc). This didn't help. So last ditch effort I've just rebuilt the fuel pump. Note: VRO is not used. Now runs dry after a few minutes on the muffs. I've put a clear line in place and there are no bubbles before death so I'm assuming I'm running on the bowls. Pumping the primer ball will bring it back to life just as it is coughing it's last breath.

It there a trick to setting the new diaphrams/pistons in the pump? Could poor compression or bad reed be a cause. Would simply using an electric fuel pump be the answer.

Any help would be appreciated. The grandkids are looking foward to fireworks over the lake this upcoming 4th of July.

Thanks in advance for any prompt responses.................

 

[Dennisanoka]

Re: 120 VRO Fuel Pump Help

I would think that the issue is either your fuel pump or an obstruction at some point beginning inside your tank and ending at your carb. The bulb will force fuel thru where your pump can not. So before we second guess your pump, even though you said you rebuilt it, I would rule out any obstruction in any portion of the fuel delivery system. Have you tried a different fuel tank and different fuel lines with it?

To some degree it sounds like it ran better before you rebuilt the pump. If that is the case, we may have to revisit the fuel pump rebuilding after you know for certain there are no obstructions getting the fuel from inside the tank.

 

[Joe Reeves]

Re: 120 VRO Fuel Pump Help

You can check the fuel pump operating power pulse simply by removing the spark plug wires and the pulse operating hose from the fuel pump, then crank the engine over a few times. The downward stroke of the piston should force out quite a pulse from that hose...... and I strongly suspect it does.

I would be leaning more to something like a oversight being made in the rebuilding of the fuel pump (easy to do).