she runs but then shuts down.....

[GaiaOrion]

Hi guys, a friend of mine has a rebuilt carb, newer filter, etc...
he ran his engine for a few minutes then it quit, and can't start again.
He has taken the carb off to check it and it seems O.K.

Any suggestions for troubleshooting this one?

Thanks

M.

[timangiel]

if an engine wont start, usually you are either not getting gas or you are not getting spark. Try to at least verify you are, or are not, getting spark.

[dabnis]

Assuming you are getting spark, is there fuel in the float bowl? If so, could be some debris found its way into the main or idle jets? Also check the float for proper travel. If no or little fuel in the bowl check to make sure the tank vent is open. If you can see inside the filter bowl it should be full with no air space visible. If its not full you may have an air leak on the suction side of the pump. Check all connections carefully and consider replacing the fuel lines if nothing else works

[SAMUELBURNS]

GOrion - After confirming you have spark, try removing a sparkplug and shining a flashlight into chamber.........chances are it's either completely dry inside, completely flooded, or water in gasoline appears as beads on plug tip. If dry, squirt 3-in-1 oil plus nose-dropper of gasoline into cylinder, replace plug, crank; a short running burst with engine then dying confirms that it is not getting fuel. If H2O in fuel, could be bad gasoline, leaky head gasket, water backing into engine from your VerniLifter exhaust riser, or (worst of all) a leak from water cooling jacket into manifold................not uncommon in 30+ year old A-4 blocks.

[CalebD]

How long did it run before quitting?
Could also be the coil or even the oil pressure cutoff switch if you have an electric fuel pump.
I'd ask this Q at the moyer marine forum.
Moyer Marine Atomic 4 Community - Home of the Afourians - Powered by vBulletin

[erps]

My son-in-law fought with an Atomic 4 that would run great for an hour or so and then it would quit. It wouldn't start until it cooled down. We were both convinced it was a fuel starvation problem and worked from that angle for a long time, but the problem persisted. His problem turned out to be a bad coil that would fail after it heated up, but start working again when it cooled down.

[CalebD]

As Ray said, the coil can heat up which can reduce it's ability to produce the voltage to produce an adequate spark to keep the engine going. It depends on the type of coil you are using but they all can fail - I think. Some are oil filled and others have a more firm filling agent. Check on the Moyer website for the different types they sell.
A new coil at a Napa or other auto parts store place is only about $30 - 40 (or less).

[RobGallagher]

A-4's run great with the correct parts, clean fuel, and good spark.

I have found that previous owners have often gone the cheap route using mail order auto parts and/or the engines suffer from a lack of routine maintenance. They run so well and are so reliable they are often neglected until multiple things may start going bad at once. That is the biggest problem with them when you first start out. Something like... a cheap coil that is failing, old fuel lines, and a clogged fuel vent.... it will one pull their hair out and start thinking about $10K diesel replacements that are not needed.

Go to Moyermarine.com and get the engine in order one step at a time. The forums are amazing!