Fuel flow problem

R

Rwinemaker

New member
I'm having fuel problems that sound very much like the threads I've read about the fuel dip tube being cut orthogonal allowing the tube to become restricted due to it sucking onto the bottom of the tank. The fix apparently is to cut the dip tube at an angle. I thought I'd check mine to see what it looked like. The pickup tube appears to be held by a nut on the outside if loosened would allow the bushing and dip tube to drop into the tank. Does anyone know how to pull the dip tube? Maybe, I'm not interpreting what I'm seeing correctly. Any advise would be greatly appreciated.
 
Problems have also included a clogged intake screen at the bottom of the pickup tube, restricted air vent, bad bulb or hose, filter plugged, or anti siphon valve bad. Yes, some pick up tubes are held with a nut around the top of the tube. Some have a flange screwed into the tank. Some have a threaded fitting brazed to the tube.
 
We experience fuel starvation at about 2000RPM, and we expected to find either a sticky antiphon valve or a flatten end of the pick up as others have described. On each of our 30 gallon tanks, the fuel pickup is screwed into a hole in the top of the tank which is slightly canted such that the tube enters the tank at about 10 degrees or so about one inch from the side of the tank. The tube is a very stiff plastic, and the end is cut squarely across. The tube is cut precisely to a length such that one edge contacts the bottom (or near bottom) and the other edge is off the bottom by about a 1/8th inch. As the gas sloshes back and forth, it can cause this tube to bend slightly so the end is nearly parallel to the bottom of the tank which we think then restricts the fuel pick up.

Fisheries in Seattle had the exact pick up in stock. It is a screw in 90 degree aluminum fitting with the hard plastic force fitted. We cut the new tube about 1/8" shorter than the old one and angled it up at a slight angle. This seems to have fixed it as we ran both tanks for some hours without a problem whereas before it would cut out after about five minutes. The vent valve doesn't have a screen and seems clear, but it is still being checked out (it is hard to get to) as a possible cause. All the filters are clean and the lines were previously replaced.

Tim and Dave Kinghorn
 
Tim & Dave Kinghorn":56r34ln8 said:
I've posted pictures of the fuel lines on our photo album's site, Sound Venture, that show the angle of the line going in the tank.

Tim and Dave Kinghorn
Click to expand...

Hello Tim and Dave,

I like all those neat mods you done to your boat. Thanks for posting pics too.

I have a question about the fuel flow pic up 'angle' pic and how this relates to your fuel flow restriction. I may be completely mistaken...but I believe the fuel pic up enters our fuel tanks perpendicular to the TOP of the tank rather than following the angle made by the outboard wall of the tank....I contend that angle is not relevant since the fuel pick up is attached to the top of the tank. At least on my tank, the fuel flow "nut" is threaded into the top of the tank at a 90 degree angle (to the tank's top) which, in my case, caused the fuel flow to become restricted when the pic up tube, which was cut at a nice 90 degree angle, sucked up against the bottom of the tank...so I pulled out my pickup tubes and cut them at a 45 degree bevel.

OR....I could be wrong....please enlighten me

/david
 
Hi David,

It appears the Cape Cruiser folks changed tank styles (ours is an 07). On our tank the fitting on the top of the tank is welded at an angle that parallels the angle on the side of the tank. When you insert the pick up, it goes in at that angle (about 10 degrees--see photo album).
The fuel pick-up tube is attached to a 90 degree elbow, and when you screw it in to the tank fitting, one edge would touch the bottom of the tank and the other would be off the bottom by an eighth of an inch or so. But, thought the tube is stiff plastic, it still can bend a bit (and reduce the clearance to the bottom of the tank). We cut a new one about an eighth of an inch shorter and cut a slightly upward angle on the side away from the bottom to give a bit more clearance. However, you have to ensure that when you screw it in on our set up, you orient it, when tightened, to be in the correct position on the bottom of the tank. The original end was cut straight across, thus it didn't matter which side was down, the other would be up. But when I cut an angle on the end, I had to ensure it oriented correctly with the bottom of the tank when tightened down.

If yours enters the tank at a 90 degree angle to the tank top, It doesn't matter which way the angle faces when you screw it back in to the tank.

Thanks for the compliments on the addition to the boat. Although I know it violates every principle of KISS, I thoroughly enjoy tinkering with the systems. Fortunately, the boat isn't perfect so I have lots to tinker with!

Tim and Dave Kinghorn
 
Tim & Dave Kinghorn":pvuo1fc3 said:
Hi David,

On our tank the fitting on the top of the tank is welded at an angle that parallels the angle on the side of the tank. When you insert the pick up, it goes in at that angle (about 10 degrees--see photo album).

Thanks for the compliments on the addition to the boat. Although I know it violates every principle of KISS, I thoroughly enjoy tinkering with the systems. Fortunately, the boat isn't perfect so I have lots to tinker with!

Tim and Dave Kinghorn
Click to expand...

Well...then that explains it. I'll have to look closely at my tanks. I didn't think the fitting was welded at an angle but rather flat to the top. As you said, that would make a difference especially when re-inserting the elbow to which the pickup tube is attached.

Keep up the modifications...I get all my ideas from guys like you!

Thanks,

/david
 
Tim & Dave Kinghorn":60fwduvf said:
I've posted pictures of the fuel lines on our photo album's site, Sound Venture, that show the angle of the line going in the tank.

Tim and Dave Kinghorn
Click to expand...

Did you check the fuel tank vent? Sometimes they become blocked
I cant fully see the racor fuel filter head. Is the other port used or closed? Sometimes a loose port will pull in air or if the fuel line goes to a kicker, the quick fuel connector on it will not fully close and pull in air.

BTW Nice boat!

You need to add some indicator lights to the electrical panel for the full effect :wink:
 
Hi Brent,

A line from each tank goes to each side of the Rancor Filter. A single output line goes to a tee which feeds two 3-way fuel switches. The kicker fuel switch has 3 stops: 1. OFF 2. ON to kicker 3. On to a fuel pressure gauge.
The main engine fuel switch has 3 stops: 1. OFF 2. ON to main engine and 3. ON to an auxiliary line used to fill the skiff tank.

We are going to check and clean the tank vents, but they're clear when you blow air through the line.

We do have one very bright RED LED that lights up when water is detected in the aft sump by the transom drain. Other dash lights indicated when circuits are being used. It is still a work in progress.

However, we are quite confident the problem was at the pick-up point at the bottom of the tank. With our type of pick-up, this seems to have been a common problem.

Thanks for the kind words.

Tim and Dave Kinghorn
 
On visiting the thread in this forum "Tom Cat Fuel Tank Problem", we learned that there is an ASV inside the hose barb that connects into the elbow on the fuel tank of our 23' Venture. It looks just like an ordinary hose barb! Therefore, in working on the pick-up tube, the valve could have cleared itself giving the impression the problem was in the pick-up.

It would seem that this valve is not necessary according to the regulation cited on the above thread.

If the original problem was this valve, it will return (I'm back)!

As our fuel lines exit above the tank and stay above the tank, and as the motor is above the tank, we don't believe an ASV is required (see citation on above thread). Plus we have turn off valves in both lines before they enter the fuel/water separator, and a turn off in each of the two engine selection valves. One could mount a turnoff valve on each tank at the pick-up, but I don't think that would add any degree of safety. If the fuel lines were below the level of gas in the tanks and sprung a leak, gas could siphon into the bottom of the boat,but we have secured the lines with clamps to remain above the tops of the tanks. However, in an abundance of caution, we may add the turn-off valves and replace the ASV barb with an ordinary hose barb.

Tim & Dave Kinghorn
 
I recently had a similar problem, difference was it is a 1996 model so could be different configuration. The large nut at the top of my tank is actually molded into or attached to the tank. Just pull off the hose and the grounding wires and hook a wrench onto the 90 bend and turn it out. When I finally figured out that it wasn't the filter but the tank the giveaway was when while switched to the starboard tank the priming bulb flattened out. Engines ran rough and eventually, at wide open, both engines stopped. Switched the tank to port and the bulb filled immediately. So I took the pickup out. Found that the pickup tube was a surprisingly large diameter plastic tube, maybe 1/2 " or more, with a 45 degree bevel. No problem there. But the previous owner not wanting to carry unused fuel stuffed about 2" of pipe nipple into that tube to reach the bottom of the tank. I left it in there but cut about a 1/4" off and at an angle. There is also a screen in the plastic tube. All is well now. I suspect that when the top of the tank got sunlight and started to warm, it sagged enough to place the nipple down on the tank bottom and the vacuum was created.
 
I've been having fuel problems as previously reported. I thought the problem was the pickup tube sticking to the tank as others have seen. I pulled the fuel pickup tube and found the anti siphon valve stuck closed. Nothing new here but the condition of the plastic pickup tube was alarming. The port side was deteriorated so bad it broke into pieces as it came out. I also pulled the starboard pickup tube and found it also breaking down to a lesser degree. The alarming part is if the pickup were to deteriorate and break off when you are at sea for example you could end up with a partial tank of fuel you could not use. Scary! I for one would like to see a metal pickup tube. Any ideas out there? I have tried to attach a photo but I don't know how.
 
The photo needs to be somewhere accesable on the internet, try photobucket or some such site. You can also ask one of the nerds, Tyboo or Bill for an album here and put it there. Then use the IMG function.

Charlie
 
I had a mechanic tell me once that all the hoses on a boat ought to be replaced every 5 years, which, I think, is a bit soon, but when there's any deterioration showing at all, it's indeed time!

The prevailing regulations require the date of manufacture be stamped on marine fuel hoses.

Might be interesting for all of you to check yours out! (Both the date and condition.)

Joe. :teeth :thup
 
When we pulled the fuel pick-ups from the tanks, there was no sign of deterioration. Ours was put in service in the spring of 07. But I replaced them with the exact type anyway which I got from the Fisheries in Seattle. They appear to be some type of nylon or a very hard plastic.

If you figure a way to use a metal pick-up, you might want to consider aluminum tubing as opposed to copper to reduce the chance of electrolyze.

You can see a photo of the old fuel pick-up in our photo album.

Tim and Dave Kinghorn
 
We checked the hose bards attached to each tank and found no anti-siphon
valve.

The motor runs great. Therefore, the problem with fuel starvation was due to the pick-up in the tank contacting the bottom of the tank.

Tim & Dave Kinghorn
 
Hi,
My Venture's tanks were marked 2/08 and did not have anti siphon valves.The pickups are attached to a aluminum right angle fittings,aluminum hose barbs with plastic pickups with screen on the bottom of the pickups. The pickup tubes appear to enter the tank on a 90 degree angle. I removed the screens and cut the bottoms of the tubes on a 45 degree angle as suggested. I could easily blow in both directions either from the bottom of the tube or from the hose barb end. I pulled my fuel gauge senders so I could siphon all the gas out and the tanks appear to have a baffle about half way back on the tank which is parallel to the transom. I added some petroleum jelly to all fuel sender connections to prevent corrosion. Having some upcoming cruises I wanted to be sure anti siphon valves or the fuel pickups would not be a problem. I'll post some pictures in my album along with three inspection plates I cut into the cockpit, under the bunk area and by the rear door on the cabin side. Thanks for the info to all concerned.
D.D.
 
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