A4 30HP Late Model - Engine randomly shutting off in Idle

[ColeHarmening]

Hello,

Yesterday I tried to go out sailing but when I fired my engine up it ran for a minute then randomly shut off. Fired up again, ran for 30 seconds then shut off. Then I fired it up again and it ran fine for 30 minutes without an issue before I shut it down. I decided to not go out sailing after all due to those two random shut downs. I am trouble shooting the issue tomorrow and would like to know if anyone has suggestions of what I should be troubleshooting first? My three hypothesis are this:

1. Check fuel pump for clog in the line or particles blocking the passage of fuel - which caused the passage to be blocked of fuel and was the sudden shut down of my engine.

2. Check fuel pump to see if it has gone bad or has a bad electrical connection - The fuel pump may be not pumping fast enough or is randomly turning off due to a bad connection.

2. Check Wires coming from distributer cap to coil - possible bad connection or chafing of wire lead to random engine shut down

I will be running the engine for a while today again to see if I can get it to shut down again.

[JOHN COOKSON]

IDEAS

Check to be sure the choke is is working correctly and the cable adjustment is not slipping.
There may have been a bit of krap in the carburetor that worked itself loose.
Oil pressure safety switches can fail in weird manners. If it a OPSS problem the shutdowns will become more frequent over time.
Others will have other ideas.

ex TRUE GRIT

[ColeHarmening]

Check to be sure the choke is is working correctly and the cable adjustment is not slipping.
There may have been a bit of krap in the carburetor that worked itself loose.
Oil pressure safety switches can fail in weird manners. If it a OPSS problem the shutdowns will become more frequent over time.
Others will have other ideas.

ex TRUE GRIT

John, thanks for the feedback. What do you mean by an OPSS problem? UPDATE: I am running my engine this morning at the dock. Its been on a half hour and its running great. I did however just notice that my water temperature gauge is reading at its resting spot 100 degrees. My engine typically runs from 140 - 180 after its been running for a few minutes. It seems as though my water temperature gauge is not working/reading wrong. I wonder if yesterday this gauge not working is what caused my engine shutoff?. Any advice on a faulty temperature gauge is helpful! I suppose I will be needing to replace mine now.

[JOHN COOKSON]

When the OPSS does not close when the oil pressure is up it is defective.
Do you have a wiring harness between the gauges\key and the engine that have some sort of plugs in it? ("Trailer plugs") If so pull the plugs apart and check for corrosion.

ex TRUE GRIT

[Al Schober]

Fixing problems by replacing parts willy-nilly can get expensive and take a long time. Handy diagnostic tools:
Fuel pressure gauge at carb inlet. Is the fuel pump putting out?
Test light at the + terminal of the coil. Is the system getting voltage?
IR thermometer? How hot is the head/stuffing box/etc ?
Once you narrow down a problem, most of the individual components can be tested separately. I prefer to buy a new part after I'm pretty certain the old part isn't working properly.