Fuel Tank pick up problem

Tad and Toby Jackson · Posted: Wed Jun 04, 2008 1:39 pm Post subject: Fuel Tank pick up problem

Brats,

I am hoping some of you can help me with this problem. Toby and I took the Comfy Dory for an 11 day "Mini Loop" for the last 10 days of May. We launched on the St. John's River west of Titusville, FL and went north up to Jacksonville. From there we turned north on the ICW and made it up to Jekyll Island before turning back south on the ICW to our home on Merritt Island. That was the fun part...beautiful weather and wildlife and a great chance to "get away from it all!"
The problem began on the St. John's when we made the first change from running on the port side fuel tank to running on the starboard tank. After about 12 miles or so, the engine sputtered and I found that I could not get any pressure in the gas line by pumping up the bulb. Fortunately, I had not run all the fuel from the port tank and switched back and was able to pump up pressure in the fuel line easily and proceed to the nearest fuel stop in Astor, FL. We decided to run on the port tank only until we could find a marina with mechanic service. We did fill the starboard tank back up with the 2 gallons or so that we had used before the problem started. No real problem to use only the one tank as there were fuel stops within our single tank range along the way.
Ran into Marvin with the C-FLE hanging in straps from his boathouse near Nassau Sound and had a chance to talk with him for about a half hour. He told us of a couple of marinas to the north that had mechanics. We stopped at the Amelia Island Marina and got great help from their lead mechanic Kurt. He was busy trying to get an outdrive functional for a customer, but took time to listen to my problem and suggested that it might be the fuel/water separator which I had a replacement for onboard or an air leak in the fuel lines that might be creating the vacuum. Said I should start with the filter. I had tried to change the separator out that morning, but broke my filter wrench. Kurt lent me his and said he would come back by to check on us after he finished with the I/O. There was some nasty looking water in the separator and Kurt also lent us his drill driven pump to flush anymore water out. He said I would need some more separators because it would be a good idea to check it and change it out again...maybe a few times. He told me where the nearest West Marine was and also an auto parts store and lent me his truck to get there. I left a $20 in the truck for his generous loan of the truck.
I started the engine on the starboard tank and ran it for 15 minutes and all seemed ok, so we left an additional $20 for Kurt with the girl in the ship's store and headed north again. I can't say enough about how curteous and helpful they all were at that marina, especially Kurt. Well, about 12 miles or so north it happened again, so I decided to keep going north until we found a marina where I could buy new fuel lines. Stopped at Fernandina Harbour Marina at the north end of Amelia Is. and found a "Boat Shop" about 2 blocks away where I purhchased new fuel line. I changed out all of the lines and found some baaad rubber, so I figured that must have been the problem. Again, started and ran on the starboard tank for about 12 miles until the vacuum happened again.
At this point, we decided to continue north and just work with the port tank. We made it up to Jekyll Is. thinking that we would go even further north, but the Jekyll Island marina's gas tank was inoperable and the next marina north on Jekyll had quit selling fuel altogether. It was at this point that we decided to turn south for the trip home on the ICW. We were already further north than we though we would make it. Made it back home 4 days later using only the port tank, but I tried the starboard tank several times and the problem was still there.
I will pull the Comfy Dory out of the water this weekend and begin work on removing the tanks and all hoses and get to the bottom of the problem. I need to clean the plastic tanks anyway, as our governor has just signed a bill that requires ethanol added to all gas sold at stations and I understand that it will cause sludge or other crud to come off the insides of the tanks and lines and clog fuel filters. It will even ruin fiberglass tanks we have heard.
I have developed a theory about the vacuum problem and I would be glad for any comments about my theory or suggestions about what the problem might be. I think that there must be some sort of hole in the fuel pick up line inside of the tank so that when about 2 - 2 1/2 gallons are run out, the hole is exposed and allows air to be sucked into the line. It's the only explanation that I can think of at this point.
Has anyone come across a similar problem before?

Any help will be greatly appreciated....Tad

thataway · Posted: Wed Jun 04, 2008 2:00 pm Post subject:

It could have been bad fuel, but usually this will involve both tanks. Definately carry several extra filters.

Look at all of the fittings, and be sure that they are tight. Most tanks have an antisiphon valve (looks like a hose barb fitting to the draw tube at the top of the tank) This can go bad, and either cause a restriction or allow back siphoning. So check and see if there is an antisiphon valve, and replce it. Next the draw tube. The bottom may have a mesh over it to protect from debris--and this can be plugged. There may also be a crack in the draw tube and thus air is pulled into the line.

Is there fuel when you pump the bulb? (Disconnect at the end of the bulb and squirt into a container). If there is air, then a leak. If no fuel, some obstruction.

Also you may want to check the filter/water separator on the engine. Occasionally some debris gets thru the outer filters.

If the fuel is bad, you probably will want to "polish it"--that is run it thru 2 micron filters several times and flush out the tank. This requires an electric pump. A standard auto pump will work, but a marine pump is better--you just need to be sure it is ignition protected. You then need a container to put the fuel into--and then be able to pour back into the fuel tanks--often these can be borrowed.

Tad and Toby Jackson · Posted: Wed Jun 04, 2008 3:23 pm Post subject: Fuel Tank pick up problem

Thanks Dr. Bob. I had hoped you might chime in with some good information! I don't think it was bad fuel as we used the same fuel for both tanks. I will check for the anti-siphon valve when I get to work on it this weekend. When I pull the fuel line and depress the bead and pump, all I get is air with a little gas spray, so it is probably not the filter on the bottom of the draw tube. I agree with you that the most likely culprit is a crack or hole in the draw tub. It consistently would begin to shut down after running about 2- 2 1/2 gallons out of the tank, so it is probably near the top of the tube.
I am sure that all of this equipment is original, except for the supply lines that I replaced on our trip. The Comfy Dory being 13 years old, it is past time to replace all the fuel hoses and pick up tubes and fittings anyway. I like doing any work on the boat and each thing I work on gives me a better understanding of that system. Of course, I thought about replacing the fuel lines before our trip, but thought we could get just one more trip out of it before I had to do that work. Just another personal reminder of: "If you think about it....Do it!"

Thanks...Tad

Steve Grover · Posted: Wed Jun 04, 2008 4:21 pm Post subject:

Is anything blocking the over flow, breather tub. Doesn't the tank need vented to pick up fuel? Myself, I'm not sure on that tank. I know the vent must be opened on an outboard tank. Rolling Eyes

gljjr · Posted: Wed Jun 04, 2008 4:36 pm Post subject:

That was my thought too Steve.

Sounds like the vent is plugged and not allowing air into the tank. After running for a while do the sides of the tank seem to be sucked in? If they are then you need to check the venting of the tank.

Tom on Icarus · Posted: Wed Jun 04, 2008 7:06 pm Post subject:

If the tank was not venting wouldn't the primer bulb be sucked flat?

Tom

Tad and Toby Jackson · Posted: Wed Jun 04, 2008 10:07 pm Post subject: Fuel pick up line

Thanks Guys,
The tanks are the original tanks with hoses out of the top that connect to vent caps on each side of the hull below the gunnel. the chrome caps have a hole about 1/2" on the bottom with a screen inside the hole. If I blow on the hole, it is not obstructed. The plastic tanks are kind of concaved in on the top anyway which is probably where I got the water in the tank that was pulled into the separator...right around the fitting where the old filler hose connects to the tank.
Does anybody have an idea what a new pair of 20 gallon plastic tanks costs?

Thanks...Tad

CAVU · Posted: Wed Jun 04, 2008 10:43 pm Post subject:

Tad,
Great timing-I just returned from picking up new tanks at the factory for my 22. The parts guy originally quoted me $150 per tank. One of my tanks cracked on the bottom and I told him I thought it was defective from the start. Since I drove over to pick them up he gave them to me at cost: $100 each. The tank they use now is made by Moeller and is labeled as a 23gal/80liter capacity. It is shaped about the same as the older tanks except it is not as high and is wider-leaving about 5 inches less room between the tanks. The new shape is required to fit the newer boats with the molded floor. The old cover boards will still work but they will not be wide enough to cover the entire front of the tank.

Tad and Toby Jackson · Posted: Thu Jun 05, 2008 2:08 pm Post subject:

Dr. Bob,

If I find that the problem is a crack or hole in the draw tube when I get in there, is this a part that I can fabricate or find locally or will I have to contact the factory or the tank manufacturer? Same question for the anti-siphon valve?

Thanks...Tad

CAVU · Posted: Fri Jun 06, 2008 12:07 am Post subject:

Tad,
Your tanks may be different than mine-but the dip tube on my tanks was a short length of plastic tubing with a brass fitting on the end and a SS screen. It appeared to be very heavy wall tubing but is was just forced over hose barbs with no clamps. Worked well for 6 years and was still working when the tank cracked.

Salty Dog · Posted: Fri Jun 06, 2008 9:53 am Post subject:

Tad,
I had the exact same problem, except with the starboard tank. Lots of frustration as the motor would run fine at lower speeds, but once I tried to go higher speeds it wasn't long before it began sputtering. I too thought the screen at the bottom of the pickup tube wasn't obstructed because I could blow air through, but I finally broke down and tore that intake tube out of the fuel tank, and low and behold the screen was completely covered in sludge/junk. I cleaned the screen off, put everything back together and it ran fine after that. Cleaning out the tank would be a good idea too if you have it apart to prevent it from happening again in the future.

One word of advice about the way C-Dory did those tanks. The block on top of mine was aluminum, but the hose barb was brass. C-Dory didn't use any sort of mis-matched metals sealant, so when I attempted to take the brass hose barb off it promptly broke off inside the aluminum block. I couldn't find a new block like that anywhere, and I didn't want to wait for C-Dory to ship me one, so I took a plumbers tap and retapped the aluminum block, used some mis-matched metal sealant on the threads and put it back together with a new brass hose barb.

thataway · Posted: Fri Jun 06, 2008 4:33 pm Post subject:

Anti siphon valve is a standard fixture and you just need to know the thread size and hose size (take the old one along).

Draw tubes can be made of anything. With a plastic tank, I might consider copper tubing, since it is so easy to work, and use either compression or flare fittings. I have fabricated several draw tubes "on the fly"--when problems occured as we were cruising. I am not sure what the junction at the top of the tank is on your boat--they varied from year to year and model to model. But you do have to have a fitting similar to what was there, to fill the space and match any screw holes...

cemiii · Posted: Mon Jun 09, 2008 9:27 pm Post subject:

Tad, please let us all know what you find and how you went about fixing it. Thanks,

Chris

Tad and Toby Jackson · Posted: Tue Jun 10, 2008 8:05 am Post subject:

Chris,

I will be starting on it this weekend and I will try and take some photos as I dig deeper into the problem. It is a good reason to go ahead and set up an album for the Comfy Dory.

Thanks to all for your ideas and suggestions. It will be informative to find what the problem actually is.

Tad

Holoholo · Posted: Tue Jun 10, 2008 11:39 am Post subject:

I had problems with my fuel tanks unbeknownst to me when I purchased my '03 CD22 back in Sept last year. I had the same problem with sputtering on higher rpms and then had the carbs gone thru on both twin 50's. Then I changed all fuel lines, fuel filter, primer bulbs, connectors, etc. with still the same problem ocurring. Finally, I discovered that both factory pickups had disintegrated in both tanks so they were replaced and then I drained all 30 gals of fuel and added a new filter. I did notice a LOT of debris and junk in the bottom of both tanks when I cleaned them. Now, both motors are now running tip top and I am really watching as best as I can the fuel quality. Seems to me that these factory pickups were not meant to withstand fuel or alcohol and should definitely be listed as a recall item.

Vern