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.

[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.

[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?

[Marian Claire]

"The water separator / filter is mounted slightly above the level of the fuel tank." From post # 1.
Man that reminded me of my air leak issue found here http://www.moyermarine.com/forums/showthread.php?t=8205
I believe a small air leak allowed air to collect in the high spot of the system and caused my shutdowns.
Dan S/V Marian Claire

[pdecker]

Thanks, Marian Claire! I double check all the connections on the water sep / filter.

[hanleyclifford]

If at all feasible I would consider moving the filter/separator to a location lower than the fuel tank. As mentioned earlier this is not an extra burden you want to impose on the pump if it can be avoided.

[David Pugh]

This may sound odd but I had a similar problem with my engine shutting down unexpectedly. When I installed a new pick-up line in my fuel tank it was too close to the bottom of the tank and when the engine was running the tank contracted and the bottom of the tank was against the pick-up tube blocking any passage. I removed the pick-up line, cut the end on a 45 degree angle and solved that problem. Also could you blow compressed air backwards through the line the dislodge any obstructions?

Hope this helps you, Dave.