Looking for solutions. Engine runs for 6 hours stumbles to a stop but restarts to run

[pknier]

Removed, drained, and cleaned tank...new in-line filter, new rubber gas line, cleaned sediment bowl, disassembled and cleaned carburetor. New coil, plugs, points, and condenser last year. Started an 8 hour trip, engine stopped about half hour into trip, restarted with out problem, ran excellent for 6 hours, only to stop 6 hours into the trip, started up and ran 2 hours for the rest of the way. The next day ran excellent for almost 5 hours. Looking for what may cause these the uncertainty of these shutdowns that make our trip less enjoyable. Thanks for your input

[chapster5]

I am no expert but I will throw this out there, some kind of electrical intermittent issue. I would have thought maybe coil but you said it starts right back up and then runs for Hrs again.

Maybe describe better how it shuts down, does it cough and die? shut off just like using the key? Rpm's slowly lower and then die??

Smarter fella's will chime in soon I am sure.

Chapster5

[roadnsky]

Try this...

Connect a jumper wire (12-14 gauge) between the large battery terminal on the starter solenoid and the positive terminal (+) of the coil.
Connecting this jumper wire is the same as turning on the ignition switch and it will by-pass any problem that might exist in the "starting circuit", including the ignition switch itself.

IF the shutdowns stop you know you have an issue somewhere in the ignition wiring.

DON'T leave the jumper wire installed very long unless the engine is running or you'll pretty likely burn out the coil.
It's the same as having the ignition left ON

One other quick place to check is the ground wire where it passes under the distributor cap.
It is fairly common for it to get pinched or the insulating cover to get cut.

[Marian Claire]

I had a small air leak in my fuel supply system that I believe allowed air to build in the main fuel filter. The filter was the high point of the system. Same symptoms as you describe. Almost drove me crazy with the irregularity of the shut downs. You may have a small leak from the new work done on the lines, fuel pump, filter etc. A fuel pressure gauge just before the carb may provide some good info if you can watch it during operation.
Here is the long winded post.

http://www.moyermarineforum.com/forums/showthread.php?p=81137#post81137

Dan
S/V Marian Claire

[Dave Neptune]

We will need more of an idea as to how it died. Like the ign was shut off IE a sudden shutdown or did it stumble to a stop?

When it restarted did it act just fine like "normal" or was it a bit rough or sluggish?

Since it started right back up it is unlikely a fuel issue as you have a mechanical pump, correct?

Fire it up and check voltages at the connecting points on the key switch all the way to the coil. Look for loose connections and/or corrosion. Give the wires a wiggle and if you have the "trailer plug" style connector wiggle and clean if necessary. While wiggling and checking if the engine dies your probably wiggling a faulty connection.

Dave Neptune

[ndutton]

Fuel pressure and coil input voltage data during shutdown would be valuable information.

[pknier]

I have mechanical fuel pump rebuilt three years ago. I stops like turning the key off. I do not have fuel pressure gauge, but will have to add one. Is there a link for installing coil voltage meter?

[pknier]

Ran fine after start up. Will do some wiggling and cleaning. Thank everyone for their suggestion

[ndutton]

I have mechanical fuel pump rebuilt three years ago. It stops like turning the key off.

This pretty strongly suggests an electrical connection or switch problem. I'd lean more toward the switch because manipulating it to restart seems to clear the problem.

I do not have fuel pressure gauge, but will have to add one. Is there a link for installing coil voltage meter?

I don't recall a coil input voltage meter discussion but it should be simple to install between the coil '+' post and a ground. To be useful in this case the gauge should be visible from the helm so it can be observed at the exact point of shutdown. FYI, two of the five parameters monitored by the EWDS are fuel pressure and coil input voltage.

[Dave Neptune]

I did not mean a "coil voltage meter", I meant check the voltage at the coil and everywhere else on the circuit "with a meter".

Dave Neptune

[joe_db]

This is designed to find issues:

https://moyermarine.com/product/the-engine-warning-and-diagnostic-system-ktas_01_564/

It is not as easy as you might think to tell spark and fuel issue apart. Under cruise power, the engine quits stone dead pretty fast with no fuel, almost as fast as an electrical issue.
IMHO I would get a fuel pressure gauge ASAP and preferably one that can be seem underway if you don't get the warning light. I tracked down a vapor-lock issue that would have taken 100 years to find otherwise. A vacuum gauge on the fuel filter is a huge help too.

[ndutton]

It stops like turning the key off.

Hey wait, that contradicts the thread title ("stumbles to a stop"). Please confirm which is accurate.

[joe_db]

If you are moving at full speed and shut the engine down, sometimes water pressure on the prop will make it turn over a few times. This can be confused with "stumbling".

[pknier]

It is more like turning the key off than sputtering(run...stop...try to run...stop) to a stop

[roadnsky]

Have you tried the procedure I suggested in Post #3 yet?