Universal M21, long story and fuel line question
A few weeks ago I test ran the engine when the boat was on the hard. She started right up after sitting all winter. I noticed a fuel leak at the Racor water separator / fuel filter. As I wrote previously, a trip to West Marine solved the O - ring problem. After bleeding the air out, the engine started and ran fine.
This past weekend my boat was launched. I went down Saturday to move the boat from the marina to my mooring. I got on the boat and started the engine. Again, she started right up. I let the engine warm up while I checked the transmission (forward AND reverse), made sure the stuffing box didn't leak, checked the bilge pump, etc. After 5 minutes I felt confident the engine was running OK. So I cast off and motored about 1/4 mile to the town dock, so I could load sails and other gear.
The engine ran run and my wife met me at the dock and helped me tie up. As I was connecting a spring line, the engine, which was idling, just died. I was not able to restart it. It was very lucky that the boat was on the dock. It would not have been fun to have engine die when I was in the harbor, with no sails on the boat, etc.
Anyway, we forgot about the engine for the next two hours as we loaded gear, ran lines, etc. Then I tried to restart the engine. No go. It seemed like a fuel problem. I bled the lines at the fuel filter on the engine and got a steady stream of diesel. However, the engine would not run, it would get close to starting, and sputter a little, but would not stay running. The fuel pump was making a funny sound, not the usual ticking I expected to hear. I removed the output fuel line, and with the pump energized, only a trickle of fuel came out.
At this time I suspected the pump had died. Fortunately, the PO left a brand new spare pump on board, so I spent 20 minutes installing it. I bled the air from the fuel pump mounted on the engine, but the engine did not start, this time it wasn't even close.
That's when I gave up and went home.
That evening I read the factory service manual, which refers to bleeding air at the fuel filter and on the fuel injection pump. Unfortunately, the manual doesn't have any pictures. Sunday I went down to the boat. No air at the fuel filter. I could not find a bleed bolt on the injection pump. Then, reading the service manual more carefully, it mentions that the injection pump may have a 'self bleed return valve'. Ah ha, that's what I have. I energized the pump, opened the valve and then heard the pump tick as it moved fuel. I let it run for 30 seconds then closed the valve. After cranking for 15 seconds the engine roared to life.
I was now very happy. I let the engine run for 10 minutes, ran it up and down the rev range, in gear and out of gear. I stopped it and restarted it, no problem.
So I went up the beach, got my dingy, and rowed to the dock. I got back on the boat, and started the engine, which ran for 5 seconds and then died.
CRAP CRAP CRAP CRAP.
I repeated the 'self bleed return valve' trick, and the engine started right up.
So, after that long winded story, I get to my question:
It seems like I have an air leak somewhere. When I installed the new fuel pump I did not use any thread sealant. No fuel is leaking when the pump is running, but could air be getting into the lines when the pump is off?
Is it likely or possible that the o Ring on the racor water separator is bad? I don't see any signs of air in the bowl.
Any other ideas? I have ordered a replacement fuel pump and some new fuel lines b/c mine are very old. If I should use thread sealant, what do you recommend? I don't want to use teflon tape because I don't know how it would hold up to diesel fuel.
Lastly, there is a big bolt on the bottom of the fuel pump. Just to see what was inside, took the bottom off. I saw a small screen in there. Ah ha! That's what the filter in my maintenance kit is for! BTW, the screen was very clean, which is what I would expect because it is after the Racor with a 2micron filter. Still, I will change it as part of my normal maintenance.
Thanks for any suggestions.
Deep Blue C, 2002 C&C 110
Mt. Sinai, NY
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