Primer causing fuel exhaustion?

[green head]

I have a 1987 Evinrude 20HP Model #E20CRCUR. In the last month I had the boat on the water(pulled it this week) I was having problems with the motor getting fuel. I narrowed it down the primer, I think. The first time it happened I was running at full throttle and the motor slowed and died due to fuel exhaustion. I was checked some obvious things and found the primer was not pushed all the way in. After I pushed it in all the way the motor worked like normal. The next few times it happened I had to push the primer in all the way or leave it out a few millimeters. It seemed that when the primer was in the sweet spot that the fuel flow was uninterrupted to the carb. Does this even make since or just a weird coincidence? If I am onto something is there a way to further troubleshoot or fix this issue.

Thanks

 

[Roberthill]

Primer is used to start engine . Looks like you have a fuel delivery problem . Could be filter(s), fuel pump ,carberator needle valve not opening,bad hoses and anything on your fuel system including gas tank .

 

[Kloctower]

Primer on the motor correct? Not the bulb on your fuel line? Primer on the motor shoots fuel directly into your intake to aid in starting so if it helps your motor run when you use it then you are having a problem somewhere else. Fuel line leak or blockage or check valve bad maybe carb issue but it's definitely a fuel problem. The primer is doing its job.

 

[green head]

Thanks Robert I know what a primer does and thanks for listing the major components of a fuel system.

​Klocktower, yes the primer on the motor not the bulb. The motor does not run any better when I use the primer while running. It just runs worse if the primer is not in the full retracted spot. Sometimes it runs better with the primer not quite fully retracted. Its weird, I wouldn't think the position of the primer would affect the motor but it seems to.

 

[flyingscott]

The position of the primer does effect how the motor runs. You can use it to warm up the motor by leaving it out a little bit allows more fuel into the motor. It's like leaving the choke half on. Sounds like your primer is working fine, when they go bad they will usually flood the motor with to much fuel. Try pumping the primer ball on the fuel line when you have that problem. Also is your tank vent open.

 

[green head]

I think I remember trying to pump the bulb as the motor was dying and it not helping. The tank vent is usually open all the time.

​Also this is a very intermittent problem. But when it happens I am usually sitting in the middle of the lake for a few minutes.

 

[fhhuber]

From the described symptoms....Sounding like the primer is causing an air leak (intermittent) which results in the engine pulling foam instead of liquid fuel.

I'd start looking at a kit to renew the primer's seals (I expect O-rings but not sure on that one)

Also possible that its an air leak somewhere else that just happens to seem like the primer is affecting it.

Cover off the power head, engine not running but in normal planing attitude, pump the fuel line bulb and squeeze hard while watching for fuel leaks.
You can't squeeze the bulb primer(pump) in the fuel line hard enough (by hand) to hurt anything that isn't ready to break anyway.

I found a cracked VRO pump case on a Johnson 150 this way. It was giving me fits trying to find what was making it intermittently not run properly.


And... Right at 30 years old... if it hasn't been done before now, I'd replace every bit of fuel line.

 

[jakedaawg]

I believe that having the primer valve partly open has masked a problem. As it is intermittent to some extent it points at a float/needle issue. If it were inadequate delivery the primer function would also be compromised as it is a valve and dependant on the same fuel suppy/pressure as the carb gets.

Just saying....

 

[racerone]

No, the primer on a manual start motor draws fuel from the float bowl.---It does not get fuel from the pump.

 

[jakedaawg]

No, the primer on a manual start motor draws fuel from the float bowl.---It does not get fuel from the pump.

Yet another reason why I should not comment on some of these little motors, I don't see enough of them. Thanks Racer, i'll stay out of this one.

 

[green head]

When I was troubleshooting the motor myself before I pulled the boat I took the cover off and looked for fuel leaks while the motor was running. I don't remember pumping the bulb and looking for a leak. I took the manual primer apart and looked at the seals and o rings. They looked ok but will order some new ones and replace anyway. Also the entire fuel system was replace about 5 years ago.

 

[green head]

I just looked on iboats parts website and they do not have one of the o rings for sale(#4). Any suggestions on where to get it?

 

[racerone]

Parts are available at your local friendly BRP / Johnson / Evinrude dealer.----Sometimes it just pays to support these very knowledgeable people.