4.3L mercruiser engine starting problems

[fredmeyer]

First time user so please bare with me. I have read the forums before and have gain a lot of knowledge and help on previous boat problem. Today my question is I have a 4.3L mercruiser (chevy) engine. I bought it used from a dealer and have been working on it over winter. Long story short I just got it running yesterday. I've been working on it in my garage and starting it with a hand held remote starter switch to start it. The problem I'm having is when I release the switch the engine dies, but runs fine when I hold the switch in. does the engine harness need to be attach to the boat harness to make stay running? I'm not sure what year the engine is but it does have a mechanical fuel pump on it.

 

[tpenfield]

Re: 4.3L mercruiser engine starting problems

Unless you are powering the ignition lead at the at the engine harness connector in some other way, which it sounds like not, then yes. The two harnesses need to be joined. The power to the ignition actually goes up to the helm to the ignition switch and comes back to the engine via the harness.

 

[Fun Times]

Re: 4.3L mercruiser engine starting problems

Is the engine out of the boat?

You may want to watch this video, engine start mov.wmv - YouTube

And have a look at this thread, http://forums.iboats.com/mercruiser...ng-mercruiser-engine-stand-update-368994.html

Let us know if the information works out okay for you or not.

Good luck.

 

[Bifflefan]

Re: 4.3L mercruiser engine starting problems

when I release the switch the engine dies, but runs fine when I hold the switch in.

In any "points" operated engine there are 2 wires that need to be attached to the + side of the coil.
One has 12 volts to it while cranking to make the spark hotter and thus the engine easier to start. This one usually comes from the "S" post on the starter solenoid. The other comes from a "switched" 12 volts source and runs through a "ballast resistor" to take the volts down to about 9. This lower voltage makes the points live much longer and still provides enough power for the coil to make a decent spark.

When you are cranking the engine you are getting the 12 volts from the starter to make it fire, as soon as you let off the trigger the power goes away and the engine dies. You are missing a wire to the + side of the coil.

 

[achris]

Re: 4.3L mercruiser engine starting problems

In any "points" operated engine there are 2 wires that need to be attached to the + side of the coil.
One has 12 volts to it while cranking to make the spark hotter and thus the engine easier to start. This one usually comes from the "S" post on the starter solenoid. The other comes from a "switched" 12 volts source and runs through a "ballast resistor" to take the volts down to about 9. This lower voltage makes the points live much longer and still provides enough power for the coil to make a decent spark.

When you are cranking the engine you are getting the 12 volts from the starter to make it fire, as soon as you let off the trigger the power goes away and the engine dies. You are missing a wire to the + side of the coil.

All Merc 4.3litre (carburetor) engines have Thunderbolt ignition systems, none had points.

OP. You need to supply power to the + side of the coil (should be a purple wire) for the engine to keep running. When you want to stop it, just pull the wire off at the battery end.

Mechanical fuel pump makes it between 1985 and 1992. Got an engine serial number? (Look here at find out where to find the serial number -> http://forums.iboats.com/non-repair...engine-serial-numbers-630103.html#post4398826)

Chris....

 

[Bifflefan]

Re: 4.3L mercruiser engine starting problems

All Merc 4.3litre (carburetor) engines have Thunderbolt ignition systems, none had points.

I learned something today. Now I can justify sitting in front of the computer most of the day. LOL