fuel line issue - need help -

[help-needed]

We purchased a Bennington pontoon 10 years ago - Model 20 SLI - Yamaha 25 HP - It kept quitting on us so we took pontoon and motor to a Yamaha dealer which was supposed to have fixed it. (There are no Bennington dealer available for hundred of miles.) The same problem reoccured as soon as we put it back in the water, after paying a questionable bill. Trying an external fuel tank on the motor made us realize that the problem was never the motor but the fuel line of the pontoon since it works perfectly well with this external tank.

The Yamaha dealer now tells us he does not do pontoons, just motors, a Bennington dealer is at least five hours away, so a mechanic friend of ours is trying to help. So far, he changed the gas water filter, changed the pump primer, still not getting its gas. Obviously there is a blockage somewhere in the fuel line. We called Bennington pontoon USA main office to see if we could access a printout of the construction of the pontoon via internet which they were unable to provide us with. The manuals that we were given at the time of the purchase do not show any such information.

We feel that there should be a small filter somewhere along the fuel line or at the bottom of the tank that could be blocked but we checked into the two traps, we checked under the floor and we cannot find any such openings.

I cannot believe that the only way to resolve our problem is to remove the motor and the transom in which the fuel tank is. So I am sending this in the hope that someone, somewhere would be able to help.

Thanks
lgneth@gmail.com

 

[gotnitro]

Sounds like you've checked everything and replaced everything except the fuel line its self. If you're mechanic friend said it will take the motor and transom removal to get to the entire fuel line for inspection or replacement, do it. That engine is light enough to lift off by hand.

 

[Potomacbassin’]

Old fuel line could be collapsing internally and creating a blockage. Or as you mentioned crud in the tank.

Ethanol and FUEL LINES - The Hull Truth - Boating and Fishing Forum

The Boating Forum - Ethanol and FUEL LINES - I recently had an issue with my Yamaha's, my starboard motor started to sputter intermitantly, I changed all the filters, everything seemed ok. Took the boat back out ran great all day, then on the way in it started again, hmmmmm..... Do I have a...

www.thehulltruth.com

I'm surprised you don't have access to your tank and have to remove anything on your transom, but if that's your observation certainly a tough deal. If it's under the decking can you cut an access hatch (warranty is over at this point)? Abandon and plumb in another tank in a better location?

Some pictures may help the brain trust come up with other solutions.

 

[Jack M]

Another thing you can try is , hooking up a portable gas can and temporary line

 

[SEMPERFI8387]

Another thing you can try is , hooking up a portable gas can and temporary line

Jack, They stated they tried that (first paragraph) and it runs fine.

 

[SEMPERFI8387]

I’d check a couple things.
1. is fuel line bulb collapsing when it quits?
2. If you pop tge gas cap when it quits do you get a “whoosh” of air?
If either of these is the case, you may have a vent problem and it’s starving for fuel.

O only have a 20hp and there’s times on EXTREMELY hot days, running full rpms, mine would stall. For whatever reason it was not venting and or vapor locking or combination of the two. I’d pop the gas cap, huge suck of air. Pump prime bulb and it would then run fine. Never really sure the cause but only would do it when approx 100 degrees out.

 

[mtudb24]

I had an issue back in 1999 on my brand new wellcraft CC ( I know, about 10 years prior to your boat, but looks like it reared its ugly head in 2012 too with this thread) where the fuel lines from the tank to the motors delaminated from the inside and caused a blockage and they wouldn't run. Sierra fuel lines had a recall at the time (unbeknownst to me) and I had a local marina inform me of this and replaced for free without having to trailer back the 2.5 hours to the selling dealer.
I am surprised you have no access to that, but sounds like its true.

Warning about Sierra Shieldsn gas line... [Archive] - Scream And Fly Powerboat and High Performance Powerboating Discussion Forums

I was battling a WOT fuel starvation problem on my boat for too long. Replaced all of the fuel lines from the tank to the Racor filter to the motor with Sierra Shields fuel line. Some folks I know recommended it since it is a laminated line that has an inner liner that is alcohol resistant...

www.screamandfly.com

Good luck and keep us posted