Fuel Shutdown Issue

[gdasw]

I apologize for the long post but want to provide as much info as I can.

I have a Tartan 30 (1976) with a RWC Atomic 4. On the Tartan 30 the engine is mounted mid ships in the cabin just aft of the mast. The fuel tank is at the stern on the port side and is quite large (20 gallons I think) and is triangular in shape, narrow at the bottom and wide at the top. The top of the tank is about 4 feet above the level of the fuel pump on the engine. We have an electric fuel pump, a sierra water separator filter and a second fuel filter. There was a check valve (now removed) and there is a shut off valve at the top of the tank. The carb was new in 2007 and I did disassemble and clean it a couple of years ago and it seems in good shape.

One of the challenges I have is using up the fuel in my tank over the short season to try and keep the fuel reasonably fresh. We usually race weekly, do a some day sailing and the odd cruise. We generally do not motor for hours. Getting in and out of our harbour is about 15-30 minutes depending on where we are going. Last year I tried to burn through the old fuel in my tank before I added fresh fuel. I get my gas from a station that does not use ethanol in their premium high octane fuel so I usually use that.

Last August my tank had fuel to just below the halfway point in the tank and while going out for a race it died. The way the engine died I suspected a fuel issue. I gave it a minute or so and was able to restart it again. We came back in and it died again on the way in and again I was able to restart it and get back to my slip.

I opened the drain on the carb and a little bit of gas came out. I ran the pump by jumping the OPSS on my oil filter (Indigo) unit and only got a slight dribble of fuel. I changed the filter on the water separator and checked the other fuel filter. I also added about 15 litres (4 US gallons) of fuel to the tank. I rechecked the flow of fuel from the pump and it was flowing well after running the pump for about 20 seconds. I did not have any problems for the rest of last year.

Over the winter I checked the fuel pick up line in the tank to ensure that it was ok. I also removed the check valve since there were some posts saying it was not required with the fuel shut off valve and I was wondering if it was causing at least part of the issue.

This year the engine has been running fine but again died on me last week while I was warming it up in my slip. I had not added any more fuel since the end of last season so the level was again down to about half way up the tank. Again I checked the carb and fuel flow and found the flow to be just a dribble. I added more fuel (again about 15 litres) and the fuel flow was fine. I ran the engine for about 15 minutes without any issues. I also checked my fuel tank vent and it is clear.

I am not sure of the make of the fuel pump on my engine and I am not sure if it is original or has been replaced at some point. It is a small silver unit and I can’t see any identification on it. I am wondering whether my issue is related the height of the tank, the level of fuel in it and the ability of the pump to draw it from the tank. As the level of fuel falls in the tank I think it becomes harder for the pump to pull the fuel from the tank and it reaches a point where it just does not have enough umph to get it to the carb.

I would appreciate any comments on my suspicions. I was thinking about replacing the pump and keeping the existing one as a spare. If I replace it should I get the facet pump for Catalina 30s which has a 3-4 PSI rating? I guess the other option is to keep the fuel level to at least above the half way point in the tank.

Thanks in advance.

[Dave Neptune]

gdasw, not so sure it's the pump. I'd first take a look at the pic-up tube in the tank. It is not uncommon for them to crack or get a pin-hole in them. Once the fuel is down to that level it could just be sucking mostly air. I seriously doubt the pump is having trouble drawing fuel up the few inches difference between full and half way, especially if the tank is above the pump. Could be a slight air leak anywhere behind the pump so do check the integrity of the hose-clamps for piece of mind.

It is simple to check the pump with a fuel pressure gage and I suggest one permanently mounted between the carb and secondary filter.

Dave Neptune

[edwardc]

How well did you check the fuel pickup?

This has all the earmarks of a leak in the pickup tube. When the fuel level gets below that point, you would start sucking air. Adding fuel would cure the prolem. I believe Bold Rascal had a similar problem a year or so ago.

With your tank so high, the pump should have no problem getting the fuel moving.

[JOHN COOKSON]

Originally Posted by gdasw

I was thinking about replacing the pump and keeping the existing one as a spare. If I replace it should I get the facet pump for Catalina 30s which has a 3-4 PSI rating?

+1 on what Dave N. & Ed said.
Don't replace the fuel pump just yet.
If you want to go to the trouble you can prove (or disprove) the problem is before the fuel pump by running off an auxiliary tank directly to the fuel pump with clean fuel when the shut downs occur.

TRUE GRIT

[Mo]

gdasw,

As the per the previous posts...sure sounds like a problem in the tank / tube. I realize you took it out over the winter but a small hole might be difficult to see. A couple of years back we had a member check his tube, had the same problems and eventually pulled the tube again. On the second check he found multiple pin holes.

Did the tube you removed actually extend near to the bottom of the tank. Also double check gauge float function.

[Dana Mace]

You're fuel pump is not working
Dont ask how I know
Dana
Capricious C&C 27 1976 mark 3

[Mo]

Dana, very possible as well. Could try a pump when the problem next occurs. I do believe I have a 5 psi pump on my C&C 30...will have to double check the psi ...will attach a pic that is actually it or very very similar. You could give Ken a call at MMI and he would know exactly what you need...

[yeahjohn]

Could it be the coil? I know we are all thinking fuel related but the coil could just be acting up... and that's a cheap starting point.

[gdasw]

Thanks for the responses and ideas. My first thought was a hole or crack in the pickup tube which is why I pulled it out for inspection. I was expecting a crack or hole but I could not find one. I looked at it very closely and pressure tested it as well. It looked in good shape.

I don't Think it is the coil. I did replace it a couple of years ago and the way it shuts down and restarts seems to be like a fuel issue.

I will look into adding a fuel pressure gauge and I will recheck my fuel lines and connections for any possible leaks.

Geoff

[ndutton]

Let's keep our eye on the prize (a reliable running engine) and as I've demonstrated many times before, I have no problem spending your money to that end.

I read your original post carefully and I'm in complete agreement with the pick up tube and fuel pump suspicions. The alternative of running around off the top half of the tank means you're carrying a half tank of fuel you can't get to. Not a great option.

I recommend getting aggressive with this and be done with it. I'd replace the fuel pump with the Cat 30 model from Moyer AND replace the pickup tube no matter how good it might look. While you're mucking about in there, be sure the fuel hoses are all A1-15 alcohol rated. If they're not clearly marked as such, change them too. Triple check the tightness of all the hose clamps at every connection. Why not be thorough?

[romantic comedy]

I like to by pass all that stuff, when trouble shooting. I get a gallon bottle, fill it with fuel, and stick a hose in it, and connect it to the carb. Now I can tell if there is a problem with the fuel delivery to the carb.

That is a start anyway. I would like to know what happens.

There is an alternative also. If the engine runs fine with more then half a tank full, then just keep it over half full. You say that tank is 20 gallons, but dont get to use it all? Then you can fill the tank half full with rocks. That would take up a fair amount of space. Rocks will only occupy about 50 percent, depending on size. Concrete might work better.

[sastanley]

RC, the only problem with that is, for racing, rocks are slow.

Get the Mr. Gasket $15 fuel pressure gauge from Amazon as Dave Neptune suggested. This little gauge has made fuel delivery diagnosis a no-brainer. If the gauge is not reading zero..there's fuel at the carb at least.

[roadnsky]

Originally Posted by gdasw

...My first thought was a hole or crack in the pickup tube which is why I pulled it out for inspection. I was expecting a crack or hole but I could not find one. I looked at it very closely and pressure tested it as well. It looked in good shape...

Geoff-
Visual inspection (unless under a microscope) isn't a certainty of finding a pin hole. Are you comfortable with how you pressure tested it?

As Dave and Shawn said, a pressure gauge in-line tells you a lot.

Neil's advice (as usual) is solid but I'd take it a step further if it were my vessel...
As long as you're in there replacing the pick-up tube, I'd go all the way and just replace the tank itself.
I know, easy for me to say. It's your money.

But IMHO, the fuel system is the most important part of your A4

[Bold Rascal]

But the fact that it eventually fuel starves and then runs fine after the addition of more fuel only to eventually starve out again sounds extremely familiar.

It's amazing how even the tiniest of hole(s) in the pick-up will stop the draw of fuel.

[JonnyQuest]

Originally Posted by sastanley

Get the Mr. Gasket $15 fuel pressure gauge from Amazon as Dave Neptune suggested. This little gauge has made fuel delivery diagnosis a no-brainer. If the gauge is not reading zero..there's fuel at the carb at least.

...and if the gauge happens to read unexpectedly high pressure, then it may indicate a blockage in the carb (or whatever else is downstream of your gauge). Don't ask how I came across that one.

Liek Shawn says, the gauge is a very handy diagnostic tool.

[ndutton]

Originally Posted by romantic comedy

. . . . . you can fill the tank half full with rocks. . . . . . Concrete might work better.

Rocks or concrete? Did I miss a smiley face?? Like this: or this:

Whaddya 'spose the concrete will do to the bottom end of the pickup tube?

[romantic comedy]

Big yellow face, with a big smile, arms waving around, with black hands waving, long legs, white shoes, jumping up and down, in a high wind, facing North, standing on the windward rail.

Are you kidding me Neil?

[gdasw]

Thanks again for the additional responses. I will order a new fuel pump and replace the pick tube as Neil suggested.

I will pass and the rocks and concrete idea for now although it does sound like a good idea. Maybe I could use sand instead.