SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: CanadianCougar on May 31, 2016, 06:40:19 PM
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Hey! First post on the forums been on the facebook group for a bit.
I have a 78 cougar bubble deck with a mild 468 n/a.
Last year I had problems with the boat everyonce in a while running out of fuel under acceleration, it would shut down. You would re-prime the electric pump (carter ~70gph rotary vane) and you would be off to the races again, it did feel like it was running out of fuel up top. Only had the boat out twice for short periods decided to deal with it over the winter.
So I noticed I had sucked one tank almost dry' the other almost full, so Re-ran the fuel lines so they were equal length hoping that may even it out a bit (Glenn has corrected me on this).
So today I go and try and start the boat to head out. Fuel pump wont prime.
Take it out bench test it. It works great.
Fuel to the pump. No fuel out of the pump. I can blow in the tank with an air hose and push the fuel up to the carb but even than the pump doesnt want to take over.
I am thinking that I dont have enough volume of fuel coming at the pump for it to pump efficiantly, as rotary vane pumps are not the best at scavanging fuel?
Soo.. How should I approach solving this?
I am thinking going back to a mechanical pump would probably be easyst as they are great at sucking fuel out of tanks..
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Sounds like s small pump to me. Maybe get a bigger one. Or is the pump gravity fed?
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Pump is gravity fed at this point. But I cant get it to prime up at all now in the boat so I am thinking I have always been lacking flow to the pump.
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If a line has a Crack or loose clamp it won't prime. Like if a straw in a cup has a Crack in the straw. Check your lines. You may be able to presure through the caps but leave the pump off and look for fuel leaking.
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Hey! First post on the forums been on the facebook group for a bit.
I have a 78 cougar bubble deck with a mild 468 n/a.
Last year I had problems with the boat everyonce in a while running out of fuel under acceleration, it would shut down. You would re-prime the electric pump (carter ~70gph rotary vane) and you would be off to the races again, it did feel like it was running out of fuel up top. Only had the boat out twice for short periods decided to deal with it over the winter.
So I noticed I had sucked one tank almost dry' the other almost full, so Re-ran the fuel lines so they were equal length hoping that may even it out a bit (Glenn has corrected me on this).
So today I go and try and start the boat to head out. Fuel pump wont prime.
Take it out bench test it. It works great.
Fuel to the pump. No fuel out of the pump. I can blow in the tank with an air hose and push the fuel up to the carb but even than the pump doesnt want to take over.
I am thinking that I dont have enough volume of fuel coming at the pump for it to pump efficiantly, as rotary vane pumps are not the best at scavanging fuel?
Soo.. How should I approach solving this?
I am thinking going back to a mechanical pump would probably be easyst as they are great at sucking fuel out of tanks..
. Put a valve on both tanks and run.one at a time.
Sent from my iPhone using SoCal Jet Boats
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I recommend what jim said. Also check the pickup's. I had a cracked one and had the same issue
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Here's what mine was like
(https://www.socaljetboats.com/proxy.php?request=http%3A%2F%2Fimg.photobucket.com%2Falbums%2Fv643%2Fsteves86ta%2FMobile%2520Uploads%2FIMG_20150530_110222_zpsze2cpyp9.jpg&hash=78ec087c901ec8df87ecb970b8e26aca7f916b41) (http://smg.photobucket.com/user/steves86ta/media/Mobile%20Uploads/IMG_20150530_110222_zpsze2cpyp9.jpg.html)
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Oh wow! So the pickups come out as a complete piece like that? Can they be easily replaced? Theres enough room to get them out with the tanks in the boat? I have all new hoses installed. But this seems very likely.
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Oh wow! So the pickups come out as a complete piece like that? Can they be easily replaced? Theres enough room to get them out with the tanks in the boat? I have all new hoses installed. But this seems very likely.
in my boat i was not able to get them out. i had to cut the tanks out then replace it
G&J made me a new pickup out of stainless for like 30.00 if i remember right
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Hacker Alert
Having absolutely, positively eliminated all other possible causes:
1) VERY PRECISELY project the location on the gunwale where the fuel suction tube would intersect the gunwale if the tube were long enough. A long drill or piece of close-fitting tubing or pipe, inserted inside the existing suction tube, can be used to do this. Shine a bright LED flashlight on the inside of the gunwale in order to be able to see where the drill/tube/pipe is on the OUTSIDE of the gunwale, and mark that location.
2) Drill a pilot hole in the middle of your marked location. Stick a rod through the pilot hole to verify your hole location on the gunwale. This is your last chance to make small adjustments in the (larger) hole location.
3) Enlarge the gunwale hole to the appropriate fuel suction tube size (3/8" or 1/2").
4) Install a Swagelok (or similar) pipe-to-tube adapter fitting in the female NPT bung on the tank. The fitting will have to be bore all the way through for your suction tube size.
5) Use your gunwale hole and your Swagelok fitting (installed in the tank bung) as a drill guide to drill out the suction tube that is welded to the tank bung. If your tube is welded to your tank fitting, then you don't need to do this step.
6) Insert new suction tube through hole in gunwale and swage in place ~ 1/2" off the tank bottom. I baloney-sliced the end of my tube to ensure that I didn't put it on the bottom of the tank.
The most important thing for you to do is use your existing fuel tank bung to help you locate the hole in the gunwale, since you will need to put the suction tube in straight.
Install a large, free-flowing filter upstream of the fuel pump to capture all of the crap that you just introduced onto the tank, if you don't already have one.
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I dont think it is fuel pickup issue.
My main issue rite now, is i cant get this pump to prime, all last year wasnt a problem.
Now i can push fuel from the tank past the pump rite to the carb with air and it still wont build pressure or move fuel once pressure is released in the tank you can watch it bleed back into the tank.
I am pretty confident I have a couple big air bubbles in my hoses not allowing this pump to create a suction.
I just am unsure how I can get rid of them. I blocked off each tank with ball valves tried pulling seperately with the same outcome.
I have no obstructions in the lines. I can blow freely into the tanks through the lines and get fuel in return.
It is frusterating as to why the boat started and ran fine on the trailer when I winterized it, now I cant get it to prime.
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Electric push fuel an manual suck fuel. If you put a small gallon tank of fuel on the floor an run a line from it to pump an its works then it might be the pickups in the tank. Wheres your water fuel sep located? Do you have a fuel pressure gauge to ck the flow on pump? Could be a weakened/failing pump.
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Mine wouldn't prime when my pickup was cracked
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I chased a fuel delivery problem from one of my tanks for two years before I finally gave up and installed a mechanical pump with a remote-operated selector valve this year.
This was on a system that had functioned perfectly for over 20 years. The fuel system was totally "against the book": A high-mounted electric vane-type pump for each tank, pulling through a spin-on type filter. A low-restriction check valve on the outlet of each pump allowed me to draw from either tank without filling the other. But it worked well for over 20 years.
Then one of the pumps started losing its prime frequently a couple of years ago. I replaced the pump twice, replaced the filter housing and filter, added additional tank vents, pressure-checked the system umpteen times looking for an air draw/leak, and finally drilled out the tank suction tube (see above), figuring that the suction tube was cracked inside of the tank where it attaches to the tank bung. To say that I was severely disappointed when that didn't fix the problem would be the understatement of the decade.
So I switched to an old-fashioned mechanical pump, with a home-brew remote fuel switching valve to allow me to draw from one tank or the other. Problem solved, and I still have no clue as to why I couldn't get the original system to work again.
Good luck with yours!
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Thanks all for the advice.
I was able to get it running today, I stuffed a hose into a gerry can and was able to watch the pump burp all the air thru the filter i have at the carb. Took the line off hooked it back up to the pump, flipped the pump on' and voila'.
I think with the lines being dry, the pump being dry, and the way the hoses wre routed left to much air infront of the pump for it to suck anything..
I am headed out on sunday with a buddy' if for some reason I loose the prime, I will be swapping to a mechanical pump and see if that solves it.
If not' I will be buying some 8" alum and making my own tanks to solve this once and for all :) !