New A4 owner, fuel delivery problem?

[Cityhix]

Hello. I've done a fair bit of reading here and on the Moyer site regarding fuel delivery problems. I have some ideas about where I should go but thought I would throw out a query.

-Late model A4 in a '71 Ericson 29.
-Facet electronic fuel pump installed more than ten years ago.
-Fuel tank is above the motor and approx 5-6 feet away.
-New carburetor installed less than ten years ago.
-Last tune up done about one year ago.
-Main fuel filter changed within the last four months.
-Failure to turn on the raw water intake resulted in overheating (240?) last weekend.

Problem:

Engine starts easily and idles beautifully. Motoring out of the harbor this week, the engine started to sound like it was faltering. The temp appeared to be fluctuating (can't recall the high/low). Motor finally stopped but restarted immediately. We went sailing and had to restart several times on our way back into the harbor. At the dock, idling was great but while tied up and in forward the motor will run great up to approximately 1400 RPM and then quit abruptly. Pulling the choke out will keep it running for another ten seconds or so.

I intend to go through the whole system up to the carburetor, replacing the inline filter, fuel lines, valves possibly, assure that the main filter is properly seated and possibly add a priming bulb. I've read of the possibility of pulling air into the system from a tiny leak. I should probably add an inline fuel gauge to make sure that we are getting good push from the fuel pump too.

I know not an easy answer but thanks for any insight!

[BunnyPlanet169]

Welcome to the Forum!

Everything you said makes sense, but let me add a little:

Depending on how long you ran hot and dry, your water pump impeller is suspect at best.

No priming bulbs, please. At least not for permanent installation. They are not rated/safe for interior machinery spaces.

A fuel pressure gauge is invaluable for troubleshooting. $15 or so at YLFAPS (your local friendly auto parts store).

Do you have an OPSS in the fuel pump circuit?

[Al Schober]

Cityhix,
I'm going to muddy your waters a bit and suggest an electrical problem - possibly the ignition switch. Intermittent high resistance in the switch (or it's wiring) will give you problems running and also make the gauges go nuts. A jumper from battery + to coil + will bypass the switch, but is only a temporary measure for diagnostics.
As for the carb, it's at the end of the fuel system and all flows to the carb - gas, water, and krap. Yeah, the filters are supposed to let only the good stuff through, but I've learned to carry a spare carb. I've lost count of the times I've had the float valve hang open or had the main jet clog - even with a Racor primary and an inline secondary filter. BTW, carb changes are quicker if you go with studs in the carb and nuts over the manifold flange.

[BunnyPlanet169]

BTW, carb changes are quicker if you go with studs in the carb and nuts over the manifold flange.

Thusly.

http://www.moyermarine.com/forums/album.php?albumid=150&pictureid=1881

[JOHN COOKSON]

As Far As The Variable Temp Reading Go......

Have a look see at the water pump impeller to see if any of the veins are broken off. If there are any pieces of the impeller in the cooling system they may be acting as a flapper valve to the water flow. This is sort of far out but still possible. Are you RWC or FWC?

TRUE GRIT

[Cityhix]

First, thanks for all suggestions.

I did swap in a new raw water impeller today. The old one was definitely looking tired.

Replaced the plugs and added a dash of Marvel into each cylinder. That made me feel like the neighborhood polluter for sure! Sprayed some carb cleaner down the intake. Replaced the inline fuel filter between the fuel pump and carb.

I also found a blown 10a fuse in a lead to the oil pressure sender. The fuel pump is supplied with power from the same unit but from a terminal on the aft side of the sender (not the lead that had the blown fuse). Not sure if this had anything to do with my problem but it seems to be running properly now.

I was rescued by a buddy who showed up today with a cold beverage. After I had everything back together, the motor kept quitting after shorter and shorter intervals. I was baffled and about to throw in the towel when he poked his head in and noticed that I had shut off the valve at the fuel tank. I was burning through the fuel in the filter. He switched it back on and all seems well.

Fun day on the boat today!

[BunnyPlanet169]

The blown fuse is everything.

The circuit is coil + to the ( EDIT usually the fuse ) to the OPSS and then to the fuel pump. The fuel pump then supplies the ground via mounting. The OPSS is a low pressure safety switch that requires minimal pressure to close, supplying power to the fuel pump only when the ignition switch is on, and the engine creating oil pressure ( I.E. Running).

Bring a spare - if the fuse blows again, you've got a problem in that circuit.

[hanleyclifford]

Questions come to mind

The circuit itself is a problem. The ignition circuit should be independent of the fuel pump. I recommend separate OPSS for both. If you are blowing a 10 amp fuse with both ignition and fuel pump that raises another question. Who is getting all the juice? Or is there another user in there? Are you in effect using a messy circuit as a coil resister?

[JOHN COOKSON]

10 amps is a lot of electricity. My bet is something was\is grounded somewhere. Maybe the fuel pump, maybe the wiring.
If you keep not rembering to turn the fuel shut off valve on put the key on the valve when you shut it off.

TRUE GRIT

[ndutton]

I load up my ignition circuit pretty heavily - without a single issue by the way - and still remain under 80% of the 10 amp fuse value.

Ignition load = 3.4 amps
Alternator excite = 0 amps (single wire self excite)
Facet fuel pump = 1.6 amps
Johnson CM30P7-1 coolant pump = 2.2 amps
EWDS = 0 amps (by design, no draw unless triggered)

Total ignition circuit load = 7.2 amps

Point being, even with considerable loads on the ignition circuit a 10 amp fuse is fine under normal conditions. That your fuse was blown indicates a circuit or device problem as mentioned by others.

[Cityhix]

The blown fuse is everything.

The circuit is coil + to the ( EDIT usually the fuse ) to the OPSS and then to the fuel pump. The fuel pump then supplies the ground via mounting. The OPSS is a low pressure safety switch that requires minimal pressure to close, supplying power to the fuel pump only when the ignition switch is on, and the engine creating oil pressure ( I.E. Running).

Bring a spare - if the fuse blows again, you've got a problem in that circuit.

OK. I think I understand. But I am confused why I was able to run the motor at all with power supply to the fuel pump interrupted by the blown fuse. Will fuel flow through the pump passively? The fuel tank is located somewhat higher than the carburetor. Maybe gravity is my friend?

Cityhix

[ndutton]

You are exactly correct. The pump will pass fuel on a gravity feed but the flow won't keep up with the running engine's demands. This is not necessarily a good thing when the boat is sitting idle. If you don't have one you might consider a positive fuel shut off valve immediately ahead of the carburetor.

[BunnyPlanet169]

FWIW - looked at mine today - it's only 5A and I've never had it go....