Runs great for 4 minutes or so

MAW31

Petty Officer 1st Class
Joined
Aug 15, 2009
Messages
217
4 times I left the dock lift at the marina where i keep my boat and 4 times after maybe 5 minutes, the motor runs rough and dies. This is in a no wake zone, so i'm more or less, just off idle.

Here's the interesting part: Each time, when i return to the lift and lift the boat just enough to hold it in place, i run the motor and it runs absolutely perfect.
Totally perplexed.

i cleaned the distributor cap, put a fresh fuel filter/water separator on, added Dry-gas even. charging system shows 14 volts when running, water and oil pressure look good, full tank of gas.

while changing the fuel pump / water filter, i poured the gasoline that was in the filter into a jar to inspect. while i detected tiny fragments of water, I couldn't say I found the smoking gun. either way, after changing the filter, the motor acted the same way.

after it begins to run rough, its almost mandatory that I goose the throttle every 2 seconds to keep it running and get me back to the dock, if i do nothing it eventually stalls.

I had the boat out 2 weeks ago, and it ran perfectly, no probs whatsoever.
What I had done in the meantime was add an A/B switch, added a second battery and the Tropical Storm Hermine passed over (I live in Florida).

two thoughts i had. First, i had water in the tank somehow from the storm, and second, the air-line to the tank was clogged. but i've only heard of a clogged breather line affecting the running while at full throttle - either way, i'm at idle, and the problem does not present itself while idling on the lift. and the dry-gas seemed to not affect anything. certainly didn't fix the issue.

've got a Yr 2000, 1900 LSX Regal, 4.3 GL motor, #4110188221, carburated.

Any thoughts as to what may be the issue?
Thanks
 

jerryjerry05

Supreme Mariner
Joined
May 7, 2008
Messages
18,076
Test the coil.
​Start and run the motor.
The coil should get hot but not so hot that you can't touch it.
When it dies touch the coil.

The vent line can affect the running even at idle.
Depends on how clogged it is.
Try blowing air through the line.
NO COMPRESSED AIR!! BOOM!!!
 

MAW31

Petty Officer 1st Class
Joined
Aug 15, 2009
Messages
217
Update: so... 2 days went by since putting the dry-gas into the tank and at that time, when I ran the boat, it changed nothing that I could tell.

The boat sat for 2 days now, and when I started it this time...voila. It ran perfect. drove around, put on a plane, idle ran for 20 minutes. ran perfect.

So, does it take time for the dry-gas to work? I'm hoping so because otherwise, i've no clue what happened.

I hate it when there is no 'smoking-gun' solution, and the problem seemingly just 'goes away'...without being able to explain it.
 
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