How to increase fuel tank vent

[RMasters]

Here is another "strange" think happening.

I have 2 fuel tanks in the front, 1 in the back. The back one is different, works flawless.

The 2 front ones are new (Seasense), "worked" for a while, but now, once I advance the throttle beyond idle, my motor stalls and the primer bulb is squeezed, pretty much telling me that the fuel can not be pumped out of the tanks fast enough, which should be a vent issues.

The fuel line is in correct diameter and was checked by my mechanic, it works. Fuel pump pumps full pressure.

So I was trying to drill out the vent hole in the fuel caps. The vent holes are so tiny, you can hardly see them. But I can't get to them as the screw (on the outside) and the seal (on the inside) cover the hole.

Any ideas how I could accomplish this? The tanks are stored underneath, so no worries about getting water in it (if the vent hole was exposed).

Or do you think opening the fuel cap slightly till you hear the pressure going out would accomplish the same (as air can go it now). Or would I spill fuel all over the place?

This is another one of those things (I currently have another weird issue), it worked for quite a while, and suddenly it does not anymore. It is a simple setup, what could be possibly wrong?

 

[slag]

Re: How to increase fuel tank vent

Have you tried just reaming out the hole first? Sometimes small spiders and other crusties will get in small passages and block them off with webs or their bodies. Sometimes simply blowing air into the tank or using a small wire will clean the hole out and everything will be back to normal.

Something else that might have occurred is that the primer bulb may have collapsed internally and the fuel cannot flow past and is sucking the bulb together. I've seen that happen.

 

[Thalasso]

Re: How to increase fuel tank vent

Here is another "strange" think happening.

I have 2 fuel tanks in the front, 1 in the back. The back one is different, works flawless.

The 2 front ones are new (Seasense), "worked" for a while, but now, once I advance the throttle beyond idle, my motor stalls and the primer bulb is squeezed, pretty much telling me that the fuel can not be pumped out of the tanks fast enough, which should be a vent issues.

The fuel line is in correct diameter and was checked by my mechanic, it works. Fuel pump pumps full pressure.

So I was trying to drill out the vent hole in the fuel caps. The vent holes are so tiny, you can hardly see them. But I can't get to them as the screw (on the outside) and the seal (on the inside) cover the hole.

Any ideas how I could accomplish this? The tanks are stored underneath, so no worries about getting water in it (if the vent hole was exposed).

Or do you think opening the fuel cap slightly till you hear the pressure going out would accomplish the same (as air can go it now). Or would I spill fuel all over the place?

This is another one of those things (I currently have another weird issue), it worked for quite a while, and suddenly it does not anymore. It is a simple setup, what could be possibly wrong?

Sounds like you are getting air in.

 

[RMasters]

Re: How to increase fuel tank vent

The vent holes are clean and open, checked it and rinsed/blown through, just fine.

Interesting aspect with the primer bulb, yet it is the same I use for all tanks, so wouldn't the same issue occur when I use the rear tank (with which I don't have any issue)? Of course, the fuel line length in the back is like 2 feet instead of 8 feet going to the front.

I am getting ready to head out, I will give it a try with opening the filler cap slightly. Thus even if it works, it might still be a weak primer bulb. Is there a time frame at which you want to replace it, just because of the material and construction issue? I have my water pump checked every year and thus good, replace it every 3 year vs. a new on (mechanic told me to do so).

Well, if it works, I might just get a new primer bulb and start all over.

Ahoy!

 

[RMasters]

Re: How to increase fuel tank vent

I guess I found the "issue". I simply unscrewed the tank filler cap a bit, and guess what, it worked like a charm! So it appears to be a vent issue, the motor (six-cylinder!) sucking out more fuel than air can go in. Now I have to try to get the vent hole bigger. Or drill another one, but then it would leak as there is no cover. Or getting a new filler cap (which would have to fit).

Oh well, it works, that's what matters right now.