HELP! Fuel issues crushing primer bulb under vacuum

S

Shrek

Junior Member
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.
 
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.
 
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.
 
The anti-siphon - is it the fuel pickup y'all are referring to? I've had the flattened bulb sporadically almost as long as I have had the boat. At least 4 or 5 times. Each time I remove the fuel line from the H2O separator that runs to the tank and blow back into the tank to clear it.

I've always suspected trash and gunk in there but there's no sign of anything whatsoever in my fileter(s). So could it be as simple as the fitting getting stuck rather than trash in the lines? As a side note, I need to replace all of my hoses as well. I may get to it this winter, hopefully.
 
the anti siphon valve is made into the hose barb fitting on the top of your tank, remove the hose barb and look thru it, you will see a check ball, spring and collar. I can't legally tell you what to do with it, But i've float tested them in the past, if it floats in water, its probably good(:zip:), I've taken a Phillips screw drive and punched the check ball, spring and collar out, just to see they were there :zip:
 
you should probably get some one to open it up and clean it out.
I know these guys are out of houma but they do good work and a fair price.

H & P Sheet Metal Works
1138 Barrow St, Houma, LA 70360
52.0MI from New Orleans
(985) 868-2761

for someone closer try calling Metro Boating to see who they deal with for their aluminum fab work. They probably know someone in the area. If I remember correctly they would bring a lot of their repair work to Jefferson Fiberglass. I don't remember if they did aluminum work in addition to glass work or not.

Metro boating
3028 4th Street
Harvey, LA 70058-2828
(504) 341-4852

If you take the tank out your self I don't see anyone charging over 2 hours to do the job including pressure testing it.
 
Sounds like good info to me on the check valve float test.

Not to derail too badly. Cterrebonne, what is the name of the 30 to 40 foot aluminum center consoles that I have seen in your neck of the woods? They remind me of big Fiberglass boats like the Contenders, the workmanship is awesome.
 
RidgeRunner said:
Sounds like good info to me on the check valve float test.

Not to derail too badly. Cterrebonne, what is the name of the 30 to 40 foot aluminum center consoles that I have seen in your neck of the woods? They remind me of big Fiberglass boats like the Contenders, the workmanship is awesome.
Click to expand...

you must be talking about the Gravois Hulls.They are very nice and built solid. I know a local guy that sold a contender to buy the Gravois.

http://www.facebook.com/group.php?gid=230652745784&v=wall

then there is another smaller co with really good lines "Gaubert Boat Co." i believe.
 
That is the one. Gravois, I read their Info section they are only building patrol boats and such. Not much info on them. First glance at one and you would swear it was a fiberglass boat. Awesome, and thank you.
 
The verdict is in.

My tank is 40 gallons. I emptied 17 gallons of fluid from the tank. 3 gallons of which was salt water. That would explain the surging. My tank vent is at the extreme stbd quarter of the boat at the transom, just below the rub rail and in front of the bilge pump outlet. I think that between the bilge and the spray from running on plane, I shoved a bunch of bayou water down the vent pipe and voila, problem. There was also a bunch of varnishy goodness in the bottom of the tank that I was able to hoover out. I blew the pickup tube out with compressed air; it was clean. I've already replaced all fuel lines with the good stuff prior to this problem and there is no pickup screen on the pickup tube, nor do I have an anti siphon valve.

My plan is to move the vent line on Friday and run it again on Saturday with a clean tank and see what happens.
 
Shrek, I think you got your basic issue w/the location of the vent fitting...that's absolutely the last place to put an air intake...no wonder it had water in the tank...our V20s vents on some models are poorly located...I repositioned mine ABOVE the rub rail and never had another problem...
 
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