1987 20hp johnson is the tank supposed to be vented?? engine bog

[03rev]

1987 20hp johnson is the yank supposed to be vented?? when my plastic tank sits in the sun it has tons of pressure . just wondering cause she bogs when i give it full gas, and when i troll for a legnth of time it stall then i have to prime the ball to restart . i know i might have a pump or carb prob., i will try to loosen the cap over the weekend and report back.

other then that if someones got some thoughts that would be awsome!!!!!

thanks 03rev

 

[jbjennings]

Re: 1987 20hp johnson is the tank supposed to be vented?? engine bog

Yes, your tank should be vented. That could very well be your problem. I was thinking there should be a vent in the gas cap on the tank. If your tank is plastic and your fuel pump is working properly, however, it would actually put a big enough vaccuum on the tank that it would begin to squish in if it wasn't vented to let air in.
Hope this helps,
JBJ

 

[Xcusme]

Re: 1987 20hp johnson is the tank supposed to be vented?? engine bog

You should see the tank build internal pressure if left in the sun and the tank vent closed. Open the vent or loosen the tank cap to relieve the pressure and run as usual. If the tank is left un-vented, the fuel pump will eventually pull a vacuum and stop the flow of fuel. The tank has to be vented to replace the used fuel with air.