Engine runs for a couple minutes, stops hard, no fuel flow

[pdecker]

Folks, this a follow-on to my earlier thread for my problem that I assumed was coil related. I installed a new coil, added a ballast resistor, and had the same problem of a hard shut down after 90 minutes and would not restart. I checked for spark and had plenty. I checked for fuel flow out of the fuel pump (disconnecting the fuel line into the carb) and had NONE. I jumpered out the OPSS, listened for the pump clicking which it did, and still had no fuel flow.

Yesterday, I installed a brand new MMI Facet electronic fuel pump, like the old one. Instead of running for 90 minutes, it now runs for only two minutes and shuts down hard. Plenty of spark, no fuel flow. Here's what I did to try to isolate the problem, and would like your advice to see what else I can do to fix it.

I disconnected the fuel line from the water separator to the fuel pump and stuck the suction end into my red dinghy fuel can. The outlet fuel line from the fuel pump runs to a coffee cup. I turned the key on, and the fuel pumped just fine from the fuel can to the coffee cup. I reconnected the pump to carb line. The engine started and ran just fine for several minutes with gas from the fuel can. So, I assume the fuel pump is working fine.

Next, removed the water separator/fuel filter element and inspected it. It is less than one year old and looked fine visually, and so I put it back.
I reconnected the line to the water separator and I removed the fuel line from the fuel tank and stuck it in the gas can. Once again, it pumped fuel into the coffee cup. I reconnected the line to the carb. The engine ran fine for several minutes until I turned it off. So, I conclude the water separator / fuel filter is fine.

Maybe it's the fuel tank vent. I was able to blow air fairly easily into the tank from the external fuel tank vent at the stern of the boat. It looked silly, but there is no apparent blockage. I removed the tank level sender through the big port on top of the tank, and confirmed there is more than half a tank of fairly fresh gas seasoned with a little MMO. I visually confirmed there was no gunk at the bottom of the tank and the screen as the fuel pickup looks clean. I reconnected everything, and it would run for only a couple minutes again and then stop suddenly. I removed the fuel tank cap to see it it is a venting issue and tried it again, and it would not start. Also, no fuel flow into the carb.

I'm thinking there must be something mostly blocking the fuel between the top fitting of the fuel tank and the fuel pickup at the bottom. How can I check, and how can I remove the blockage if there? The fuel tank is aluminum. A brass elbow is welded to the top connecting the fuel shut-off valve and the barbed fitting for the fuel hose. The water separator / filter is mounted slightly above the level of the fuel tank.

Phil Decker
S/V Catmandu
1982 Catalina 27

[JOHN COOKSON]

Bypass or short across the OPSS to prove or disprove.

TRUE GRIT

[pdecker]

Yes, I jumpered out the OPSS for these tests.

[ndutton]

It may sound out there but please try this: put more fuel in the tank, like 2 or 3 more gallons and test.

[JOHN COOKSON]

Originally Posted by pdecker

I'm thinking there must be something mostly blocking the fuel between the top fitting of the fuel tank and the fuel pickup at the bottom. How can I check, and how can I remove the blockage if there? The fuel tank is aluminum. A brass elbow is welded to the top connecting the fuel shut-off valve and the barbed fitting for the fuel hose.
Phil Decker
S/V Catmandu
1982 Catalina 27

I have a 1980 Cat27 Hull #4446.
I've disassembled the outlet fitting and have replaced the outlet tube. It's an easy job. Just have at it. I sealed it with permatex (#2?).While you have it apart it is a good idea to replace the outlet tube with a plastic tube. My outlet tube was copper when I took it apart. Having copper around aluminum makes me nervous. Also I ditched there screen on the bottom of the tube so there won't be any blockage in the tank. The filters can take care of any KRAP that might come through.

TRUE GRIT

[pdecker]

Similar problem with similar boats. I think I will inspect the pickup tube and remove that screen.

http://forums.catalina.sailboatowner...d.php?t=133015

[dvd]

Have you ever replaced the fuel tank or is it an original?

[edwardc]

Originally Posted by ndutton

It may sound out there but please try this: put more fuel in the tank, like 2 or 3 more gallons and test.

I agree. A pinhole in the pickup tube can cause these symptoms.

[ndutton]

Originally Posted by edwardc

I agree. A pinhole in the pickup tube can cause these symptoms.

We've seen it before but not often. This is one of those things that can drive you nutty if it's not eliminated early.

By the way, the EWDS would have uncovered the fuel pressure issue instantly.

[hanleyclifford]

Having your filter/separator higher than your fuel tank imposes an extra burden on a fuel pump already tasked with drawing fuel up a tube inside the tank. Easy to see how the pump could lose it's prime dead heading against the needle and seat while using insufficient fuel to keep the flow coming up from the tank should there be the slightest air leak. I recommend you install a fuel pressure gauge right at the carb. If you had a fuel return line to the tank the pump would always be circulating plentiful fuel up the pick up tube.

[pdecker]

Yesterday I removed the fuel line valve and pulled the pick-up hose from the tank. To my surprise, there was a check valve connected that I was not aware of. I unscrewed the check valve from the shut-off valve, and tried to blow through it like Popeye the Sailor Man (toot! toot!), and could barely blow any air whatsoever through the check valve. I don't know what pressure the check valve is supposed to release at, but the actual pressure required now is much much more than the 1 - 2 PSI that the Facet electronic fuel pump is rated. I found the pick-up tube, screen, valve, and elbow squeaky clean. I went to McDonald's Hardware Store in Fort Lauderdale and bought a straight connection to replace the check valve. See the photo attached.

I don't know why Catalina put a check valve in that system, but I really think it is the cause for my lack of fuel flow. My working theory of why the engine would work for 90 minutes and then shut down is that the pump would heat up (being mounted on the engine), which would somehow cause reduced fuel flow and/or vapor lock due to the shut check valve. I ran the engine for over 80 minutes at the slip, changing the speed every so often. Works great. I think it is fixed. I'll find out this weekend!

Phil Decker
S/V Catmandu
1982 Catalina 27

[hanleyclifford]

Congrats - it's a miracle that poor little pump is still alive, deadheading against a needle and seat while pulling a vacuum on the other end, and sitting on a hot engine to boot!

[BunnyPlanet169]

ABYC and the USCG require an anti-siphon in gas lines if the tank is not entirely below the level of everything else. That's probably why it's there. It can be a check valve, electric, or manual. The check valve was probably the cheapest....

[JOHN COOKSON]

Originally Posted by hanleyclifford

Congrats - it's a miracle that poor little pump is still alive, deadheading against a needle and seat while pulling a vacuum on the other end, and sitting on a hot engine to boot!

Time will tell.
If there are any more fuel delivery problems the fuel pump would be the first place I'd look.

TRUE GRIT

[Bingy]

My engine has been running fine except for longer runs.
This weekend after almost two hours of running it shut down.This has happened before and I i have replaced vent system, changed gas filter/water separator at tank and secondary small filter at pump. new plugs , condenser , coil .Gas is clean and water free.

Yesterday I removed primary filter at tank and only used in line filter at pump.

Left marina and motored up river and back at 1900 RPM for well over two hours.
Motor ran perfectly and fuel flow was constant.

I have a electric fuel pump and was wondering if the two filter systems was too much and was creating the starving for fuel.
Comments appreciated.

[hanleyclifford]

The quickest way to diagnose the fuel system is to install a fuel pressure gauge right at the carb.

[hanleyclifford]

Originally Posted by BunnyPlanet169

ABYC and the USCG require an anti-siphon in gas lines if the tank is not entirely below the level of everything else. That's probably why it's there. It can be a check valve, electric, or manual. The check valve was probably the cheapest....

In the Age of Ethanol I cannot imagine anything stupider in a fuel system than a check valve in a pick up tube. FWIW

[joe_db]

You REALLY need a pressure gauge.
Also note my boat has two filters plus the screen in the pump and has no issues with it when everything is working properly. If your filter is clogged, full of water, or leaking air it will be a problem. Leaks on the suction side do not always leak fuel OUT, but they may leak air IN which will disprupt the fuel flow.
I had some odd fuel issues I solved with a pressure gauge and two vacuum gauges, one before and one after the filter. Vacuum after the filter = clogged filter, vacuum before and after = clogged tank inlet or other issue back at the tank. I had my tank fill hose disolving and dropping rubber bits into the tank.

[joe_db]

Agree!!!!
If you are worried about siphons, you can turn the fuel pump off and run the fuel out of the carb to shut down. This is what I do. You can also buy a fuel pump that shuts itself off when it is turned off, get an electrical solenoid valve, or turn a manual valve on and off.

Originally Posted by hanleyclifford

In the Age of Ethanol I cannot imagine anything stupider in a fuel system than a check valve in a pick up tube. FWIW

[JOHN COOKSON]

Bingy
Is your engine a late model A4 and does it have a wire that is co joined at the OPSS with the wire to the electric fuel pump the other end of which runs around the back of the engine and under the distributor to the starter motor?

TRUE GRIT

[Marian Claire]

"Leaks on the suction side do not always leak fuel OUT, but they may leak air IN which will disprupt the fuel flow."

"You REALLY need a pressure gauge."

+1

Dan S/V Marian Claire

[Bingy]

John
Engine is a late model installed on a 1978 C&C 34,with parogon reduction gear and Martec 2 blade folding prop .
Will check wiring in morning and report back.
Please explain why you asked?

[pdecker]

Originally Posted by joe_db

You REALLY need a pressure gauge.
Also note my boat has two filters plus the screen in the pump and has no issues with it when everything is working properly. If your filter is clogged, full of water, or leaking air it will be a problem. Leaks on the suction side do not always leak fuel OUT, but they may leak air IN which will disprupt the fuel flow.
I had some odd fuel issues I solved with a pressure gauge and two vacuum gauges, one before and one after the filter. Vacuum after the filter = clogged filter, vacuum before and after = clogged tank inlet or other issue back at the tank. I had my tank fill hose disolving and dropping rubber bits into the tank.

I thought the fuel problem was fixed, but it's not. I'm going to install a couple vacuum gauges and a fuel pressure gauge as recommended above.

On Saturday, I motored down the ICW to a resort marina for the weekend. It was a three-hour run and I had no problems at all. The fuel tank was down to 1/2 full at the end. Yesterday morning, I put in five gallons of gas from my can which brought it up almost full. The engine ran fine for two hours and then I had another hard shut down. I had spark, but no fuel flow to the carburetor. I could hear the new fuel pump clicking while the engine was cranking, so I don't think the pump or OPSS was an issue. My water separator / filter is less than a year old, but it could still be the culprit. But I still have not replaced the fuel pickup line in the tank since it looked so good when I took it out, but I might just replace that just to be sure there are no leaks. Anything else I should try?

[hanleyclifford]

Your theory from post #11 about heat and vapor lock is sound. Once you have your fuel pressure gauge in place it will be interesting to see if pressure fails suddenly or deteriorates over time. It would also be interesting to know how hot that pump is getting. Next event, check the temp on the pump - be careful; it could be really hot.

[pdecker]

Thanks, Hanley! I'll pick up a non-contact pyrometer to check the temperature of the fuel pump. Perhaps the common thread of my problems is that it happens when the engine is at its hottest and it's a really hot day here in S. Florida. Yesterday, it happened at about 3:00 pm. I'm thinking of just moving the fuel pump from the engine to the bulkhead now on the assumption that it's vapor lock from the pump being too hot. But maybe I should wait to get some readings from the gauges to see if it's a clogged water sep / filter. Towboat US is going to get tired of towing me home one of these times.