43 merc starts then dies after a few seconds

Engine started perfectly and t

Engine started perfectly and then stopped after about 4 seconds. Over the next hour the engine would crank over fine but had absolutely no ignition. 3 hours later tried it one last time and it started right up and then died after 1 or 2 seconds. I don't know if it has anything to do with it but we have had heavy rain the last 4 or 5 days. Any ideas?

"What year 4.3L? Check for mo

"What year 4.3L? Check for moisture under the cap. Check for a rusted optic sensor under the rotor. Replace corroded ignition cap, rotor. What about the spark plugs?

Try this test.

Tests for Thunderbolt Ignition:
W/ignition key on AND BILGE WELL VENTILATED OF GAS FUMES!!!

#1 - Connect your voltmeter neg. lead to the engine ground and pos. lead to the white/red wire terminal at the dist. It should read 12 volts.

#2 - If 12 volts is present, remove the coil spark wire from the distributor and connect it to a spark gap tester to ground. Remove the white/green lead from the dist. terminal. Turn the ign. key to on and strike the white/green lead to ground. If there is spark, replace the ignition sensor in the dist.

#3 - If there is no spark, substitute a new coil and repeat test #2. Now if you get spark, install a new coil. NO SPARK, replace ign. amp.

#4 - In #2, if there is No voltage present, disconnect the white/red wire and check it again for 12 volts. If 12 volts is present, replace the ignition sensor inside the dist. cap. If no 12 volts present w/it disconnected--ignition amplifier is shot and must be replaced."

"Thanks Guy, The engine is a 2

"Thanks Guy, The engine is a 2002 4.3 serial # OM series. Going to try a cap and rotor this morning and see if that makes a difference."

"check for spark at plug, and

"check for spark at plug, and if got spark try starter fluid or carb cleaner into intake and see if it will start. This will check the basics and put you on the right track as what needs fixin, ignition or fuel.

Kurt"

Are you sure you have no ingni

Are you sure you have no ingnition or maybe you are not getting gas to the carb???

If no gas read below.

You have a electric fuel pump correct?

The fuel pump will not run unless there is enough oil pressure. There are two wires (same color wire) going to the oil pressure sending unit that if removed and jumped together ( only for testing and must be put back on when done testing!!!) will allow the fuel pump to run with the key in the on/run position. Remove the fuel line from the carb and try to put/aim it in a bucket.
Turn the key to on.run and confirm you have fuel comming out a a good rate/amount. If you could do this a different way and I am not suggesting this but the gas should shoot out several feet if the pump is working correctly.

good luck

Try Bypassing the oil pressure

Try Bypassing the oil pressure switch for the fuel pump. Mine was clogged and fuel pump wouldn't run. Funny thing was the day before I had been out all day and it was fine. Put it in the lake the following day and it wouldn't run. The replacement switch had a bigger port so my thinking is that it has been a problem....