HELP! Fuel issues crushing primer bulb under vacuum
 

Sorry for the long post, but please bear with me. I could sure use the help of the brain trust.

My boat is new to me. The boat sat up high and dry for an unknown length of time before I bought it. I filled the aluminum tank with 40 gallons of new fuel and promptly had significant fuel issues, including pulling a vacuum on the primer bulb.

The first time I ran the boat, I could not even get onto plane before I crushed the primer bulb under vacuum. I burped the primer bulb and the boat restarted but the same thing kept happening over and over again. Vent line clear and functioning. Opening the fuel fill did not burp the system. There is no check valve in the supply line at the tank. Limped back to the dock at idle with periodic burps to the primer bulb necessary.

When I got home I replaced the fuel filter which was full of varnishy looking flakes and a bit of water. I pulled the sender and siphoned about 7 gallons out of the tank and tried to siphon out all of the particulate matter that I could see. Ran the boat again and while it did not pull a vacuum on the bulb, the motor would not rev out.

Took the boat home again and replaced the filter again, put a spare filter on the boat, put in more fresh gas and tried it again. This time, I ran through 15 gallons with no problems, motor ran great and reved out with no problems. At gallon 16, the boat began surging with the surging getting worse as I ran. I changed out the fuel filter for the spare while on the water (old filter had gas the color of mud and large particulate matter settled out to the bottom) and did great for another 3 miles when the boat began surging badly again and again pulled vacuum on the primer bulb, crushing it.

This time I burped the fuel filter (spin on cartridge) and had to continue to do so to get the boat back to the dock while on plane. Boat would still rev out so long as I kept burping the system. Checked the fuel filter after it was back on the trailer and still dirty as before.

Despite the dirty filter, I cannot for the life of me determine why this thing is pulling a vacuum on the bulb unless there is just too much crud at the fuel pickup for it to be able to flow more than 10 GPH. But that does not make sense to me because when I burped the system, the boat ran at 12.1 GPH the whole way back to the dock. Aren't these Sierra cartridges bypass filters anyhow?

Anyone have any thoughts on what might be the problem here and how I can fix this? :cen:

Where is the vent outlet on the tank? At the front or rear of the tank? It could be air locking. Also do you have an elbow at the tank? Some have back flow preventers and some just get clogged very easily. We pulled bumble bees out of the elbows on my Sportsman when it kept dieing on us.

If you think the tank is very dirty you may have to do what i did to my 250 Sportsman, cut a 6" circle through the tank and clean it manually. I had to pull 50 gallons of fuel out of the tank and then filled it with water before cutting. I pumped all the water out and flushed it with the garden hose and let it dry for a day. I then took a piece of 1/8" aluminum and used gasket paper to seal the hole back up. The only problem i have had since then is water getting into the tank due to a piss poor design. The overflow was getting flooded in rough water.

sounds like the filter is doing its job and you have a lot of crud in the tank. try running on a portable tank and see if the problem goes away.

replace all your fuel lines. Does it have the grey "quicksilver" fuel line? Cut a section off, slice it length wise, and open it up. You will probably see the inner lining of the fuel line turning brown and coming apart. Replace all the lines from the tank till you get above deck with A1 type line, its a little more, but it holds up better, replace all the above deck line with good quality B1( I use trident hose), replace the primer bulb with a good one made by Mercury, Bomb, or Yamaha. Make sure your water sep filter housing is flushed as well. Check the filters/strainers on the engine as well.

Oh, and BTW, that thing doesn't have a fiberglass tank does it?

your boat looks sharp man. in addition to what spare said, if you are replacing all the hose. If it were myself I would trash the anti-siphon fitting for a standard brass barb.

Thats what was causing the same problem on mine.

I was having the same trouble once (bulb sucked flat), the anti-siphon was stuck.

I Agree with patdaddy running on a portable tank and see what happens sounds like the reg. tank is filled with crud

I've already replaced every fuel line in the boat. I also replaced the primer bulb. I pulled the fuel sender and pick-up and hoovered out the tank as best I could see and reach. There is no screen or anti-siphon valve on the tank.

I am taking it apart again on Wednesday and see whats happening then.