Cold Shutdown

[JackConnick]

Hi;

Boat starts up great, runs out of gear fine, warms up, revs good. But then if I put it under load it runs ok for a minute or so with good power, but then slowly shuts down. No amount of throttling back and forth will stop it from shutting off.

I can restart it fine, but same deal, shuts down after a minute under load. If I sort of baby it a bit and gradually increase power under load it will run fine, usually about try 3. Runs fine the rest of the day, restarts fine.

Just happens on first start of the day.

I just changed both fuel filters. Gas was old, but I added 2/3rds of a tank of fresh and some Stabil and SeaFoam. Gas appears clean and clear, no water in separator. Same deal.

I guess my next chore would be to clean the carb... or just keep adding some more new gas and see if if stops it?

Ideas?

TIA,
Jack

[Al Schober]

No idea what's going on, but two recommendations.
First, add a pressure gauge at the fuel inlet to the carb. Fuel issues will show up as a drop in inlet pressure.
Second, add a test light to the + terminal of the coil. Perhaps an electrical issue?
Another thought, while it's shutting down, give it a shot of starting ether and see what happens.

[joe_db]

No idea what's going on, but two recommendations.
First, add a pressure gauge at the fuel inlet to the carb. Fuel issues will show up as a drop in inlet pressure.
Second, add a test light to the + terminal of the coil. Perhaps an electrical issue?
Another thought, while it's shutting down, give it a shot of starting ether and see what happens.

^
What he said.
Get the fuel pressure gauge! I solved an issue that I would have NEVER figured out without one.
Also try what he said with the ether. If the engine revs back up, it is lacking fuel.

[JackConnick]

It starts right back up easily, that's not the issue.

What problems did you solve by having a fuel pressure gauge? Bad fuel pump? I have a Moyer electric.

I thought about the coil, but usually that issue is when an engine has been running for a while and the coil gets too hot.
I solved that issue with mounting a high output coil on a bulkhead off the engine.

Jack

[Dave Neptune]

An electrical issue will usually cause the engine to just stop like you turned it off.

A weak fuel system can idle and often restart but when throttle is applied the fuel can't keep up with demand and it will fade away and possibly die AND still be able to restart and idle.

What is the fuel pressure at idle and what is it when throttle is applied in gear?

Could be the fuel pump, a clogged filter or a vacuum leak in the fuel system before the pump. A simple gage will answer all of that.

Dave Neptune

[Surcouf]

It starts right back up easily, that's not the issue.

What problems did you solve by having a fuel pressure gauge? Bad fuel pump? I have a Moyer electric.

Jack

Seen several times of this forum: a plugged vent line on the fuel tank. Engine runs fine for some time, then tanks gets into negative pressure when gas level goes down, pump cannot suck gas anymore, engine stalls. Quickly after, engine can re-start, until it stops again... This can be trouble shooted with the ether when it starts stalling, or with a fuel gage

Another usual cause of stalling after some time is an overheating coil, but you cannot usually re-start immeadiatly...

[JackConnick]

OK, but this is very intermittent. Just happens on the first cold start and then resolves itself after a couple of times. A plugged vent would be more pervasive.

I'll check the fuel lines and tighten anything I see. As I said, I changed both filters.

Jack

[Sam]

Question can be answered by opening fuel cap and see what happens with starts.

[ndutton]

Happens only when it's cold and no mention yet of possible choke issues?

[JackConnick]

Choke is fine.

I talked to Don and he said any of the above would make it run bad all the time, it wouldn't be intermittent.

He thought it was some dirt or something in the carb. He had me do the hand on the air intake thing a couple of times as it was shutting down.

It seemed to fix it, but it needs another test when cold.

Jack

[Indy]

Does anyone have a nice photo of a fuel pressure gauge installed with a mechanical pump?

[GregH]

Does anyone have a nice photo of a fuel pressure gauge installed with a mechanical pump?