No fuel to sediment bowl

[Tryoung]

I reinstalled my newly-cleaned-and-reassembled carb today. The engine would not start afterwards. I saw that the sediment bowl on my mechanical fuel pump was bone-dry, no fuel at all. No fuel smell either. Prior to removing the carb, I hadn't had any fuel pump problems. When I took the carb off I closed the fuel line valve to the fuel pump (at the top of the fuel tank) -- and turned the valve back on prior to trying to start. I also have about half a tank of fuel. I have a simple in-line fuel filter (fairly new) just before the fuel pump.

I tried using the the manual pump lever and the also cranking the starter motor an excessively long time (maybe 20 seconds) several times (I did this with the raw water turned off).

Is there something else I can or need to do to prime the fuel pump?

Is there a test or check that I can do to check the fuel pump?

Is there anyway that the carb could be causing this issue? This is the first time I removed and cleaned my carb. I would not be surprised if I did something wrong (although I did try to follow the Moyer Manual closely).

Thanks,
Tim Young

[Cool Beans]

On my pump, I can put my finger over the outlet and either bump the starter or work the manual lever, and feel some air pressure. It took 10-15 seconds of hand priming the pump to get fuel to the carb, and another 10 seconds or so to get the motor to start.

If the needle is stuck in the seat, you might not be able to prime the fuel system. Air pressure will build up to the point the diaphragm stops pumping (just like if it was pumping fuel). Of course if it isn't pumping, that means it isn't pulling. . .

You can pull the outlet hose and put it in a can and try pumping the lever and see if you get fuel flow. If you get fuel, then you definitely need to open your carb up again.

[Tryoung]

Thanks for the reply! A stuck needle seems like a possible issue, based upon my recollection of trying to make the float parallel to the surface of the housing.

Before trying that I'll disconnect the U-shaped tube and check for suction while cranking.

Thanks,
Tim

[sastanley]

Tim, I ditched the U-shaped tube and went to soft hose & barbs between the pump & the carb..this also allows you an easy way to add the little polishing filter & a fuel pressure gauge to see what you're really getting, in terms of pressure in the fuel line.

It was a great diagnostic tool this weekend when I had an unexpected shut down...I must have had some air in the fuel line, because the gauge said 0 PSI for quite a few seconds while cranking after the shutdown, when previously it was showing 2.5 PSI while running. Once it burped out the air and pressurized, we were back in business and the engine ran great the rest of the weekend with a nice solid 2.5 PSI. I also tightened up all the clamps, as it is possible I was introducing air in at one of the fittings, which is a slight downside to soft hose with all that stuff in there. Each fitting adds several possible leak areas, but I personally feel the benefits of the polishing filter & gauge outweigh the negatives of extra clamps.

[Tryoung]

I finally got back to my boat today. Still no fuel through the pump.

I disconnected the inlet fuel line from the pump, blew air into it, and heard bubbles in the gas tank - no blockage in the line.

I reconnected the fuel line and disconnected the U-line from the pump to the carb (I might try the gauge if this problem continues to baffle me!). With this setup I first worked the manual bailer. With my finger on the outlet, I don't feel pressure, but I hear it when I take my finger off.

After working the bailer for about a minute (no finger over the outlet), no fuel came out the outlet and there was no fuel in the sediment bowl. I tried the same thing with the starter motor (gingerly at first, worried that I'd spew gas everywhere). Still no fuel out of the outlet and no fuel in the sediment bowl.

At that point I pulled the the pump off and took it home.

If the manual bailer provides pressure to the outlet, does that prove that the pump is working? Or could the pump still be at fault?

If the pump is working, what else could be at fault? Could a small air leak cause NO fuel to the fuel pump?

When I started this project the engine started and ran fine except that it sputtered and stalled at idle. I figured it was a carb issue (which is why I first took off the carb for cleaning). Could this really have been a fuel pump issue?

Or could taking the carb off to take home, and leaving the pump outlet open to the air have caused an issue to the pump?

Thanks,
Tim

[Cool Beans]

I'm guessing you hear a little "pfffft" when you pull your finger from the opening? That means it is doing something. . .

An air leak could prevent it from pulling fuel. If you can continuously pump the manual lever, and air is coming out, you might have an air leak somewhere.

Not sure what else to throw out there. . .my only fuel pump experience says "if the pump don't work, nothing does"

[67c&ccorv]

Try rebuilding the mechanical fuel pump with MMI rebuild kit...you already did the carb;

...might as well do the pump at the same time.

[67c&ccorv]

Originally Posted by Tryoung

Thanks for the reply! A stuck needle seems like a possible issue, based upon my recollection of trying to make the float parallel to the surface of the housing.

Before trying that I'll disconnect the U-shaped tube and check for suction while cranking.

Thanks,
Tim

The carb float comes after the fuel pump in the fuel flow chain - if you are not getting any fuel to the carb the problem lies between the carb and the fuel tank.

I'd be rebuilding the pump if it were me...and working my way back to the fuel tank if that did not solve the problem.

[Tryoung]

Success!

I tested the fuel pump at home with an extra length of tube and a gas can. At first it did not work. I added fuel to the empty sediment bowl and it worked.

I noticed that I had a small air leak in my test setup - between the hose that ran to the gas can and the inlet fitting on the fuel pump. Each time I pulled the hose out of the gas can the fuel in the hose would run out. But no fuel would run out of the sediment bowl no matter how I tilted the pump. That taught me how a tiny air leak can completely screw up your fuel delivery.

I reinstalled the pump on the boat, along with a new Racor filter. Engine started easily and idled smoothly. I still need finish carb installation - tweaking the idle screw. And the electronic ignition - adj the timing.

The real test will be when I take it out and get it up to speed for an extended period.

After doing this work I see two more Moyer upgrades I want to make - (1) change the oil pressure regulator to the early version and (2) add the oil change fitting.

C&C - I thought long and hard about rebuilding the pump since it was out. But the pump seems fine, and I didn't want to wait for the rebuild kit. I may do that in the off season.

Thanks to all for you input!

Tim

[toddster]

Well, it seems like an obvious point, but I just re-commissioned the engine with a new racor filter, new fuel lines, and freshly scrubbed out sediment bow. That's a lot of air to purge, and the little manual pump only moves a cc or two per stroke. I did use a little suction to get fuel to the filter. Then as per the moyer manual, I removed the plug on the bottom aft side of the carb to prime the system. You could hear the rush as the fuel hit the sediment bowl . Yeah, I had a few spills and leaks to clean up. Lots of fittings on that racor setup, plus I added a drain valve and a shut-off valve.