engine only runs when hook up Pos terminal of battery to Purp wire on startersolenoid

[synergy141]

I have a 1994 mercrusier 4.3 LX. I was having starting issues, first thought was the carb, cleaned that all out, still the same problem. Starting and shutting off 2 seconds later. I got a tip from another forum. I hooked up a wire with alligator clips to my postitive terminal on the battery then ran the other end to the purple wire on the coil. engine now fires up right away and stays running. The only way to shut it off is to disconnect the wire with the alligator clips. My question is What parts do I need to replace?

 

[thumpar]

Re: Engne only runs with wire hooked up from Pos terminal of battery to Purp wire on

Re: Engne only runs with wire hooked up from Pos terminal of battery to Purp wire on

The resistor wire is probably bad.

 

[synergy141]

Re: Engine only runs with wire hooked up from Pos terminal of battery to Purp wire on

Re: Engine only runs with wire hooked up from Pos terminal of battery to Purp wire on

is it only one wire? any idea on color? where is it located?

 

[thumpar]

Re: Engne only runs with wire hooked up from Pos terminal of battery to Purp wire on

Re: Engne only runs with wire hooked up from Pos terminal of battery to Purp wire on

Usually it is purple and runs from the alternator to the coil. Easy way to check it is measure voltage at the coil with the key on. It should be around 9v.

 

[rodbolt]

Re: Engne only runs with wire hooked up from Pos terminal of battery to Purp wire on

Re: Engne only runs with wire hooked up from Pos terminal of battery to Purp wire on

sounds more like the emergency stop switch is pulled, or bad.
cause its bypassed at engine start and back in at engine run.
check it. should be closed for running and open to shut down.

 

[synergy141]

Re: Engne only runs with wire hooked up from Pos terminal of battery to Purp wire on

Re: Engne only runs with wire hooked up from Pos terminal of battery to Purp wire on

I pulled out the emergency stop switch while it was running and nothing happened.It diddent shut the engine down.

 

[thumpar]

Re: Engne only runs with wire hooked up from Pos terminal of battery to Purp wire on

Re: Engne only runs with wire hooked up from Pos terminal of battery to Purp wire on

I pulled out the emergency stop switch while it was running and nothing happened.It diddent shut the engine down.

That is because you had the jumper on the coil. I forgot newer boats had those. Measure for ohms across the switch contacts like redbolt said.

 

[synergy141]

Re: Engne only runs with wire hooked up from Pos terminal of battery to Purp wire on

Re: Engne only runs with wire hooked up from Pos terminal of battery to Purp wire on

sorry it isnt my coil that I hooked the wire to. Someone off another forum told me I hooked it up to the purple wire on the started soleniod.



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[Alpheus]

Re: Engne only runs with wire hooked up from Pos terminal of battery to Purp wire on

Re: Engne only runs with wire hooked up from Pos terminal of battery to Purp wire on

Here is a link to the Mercruiser service manual. The wiring diagram is in there and its pretty simple. Learn it,live it, love it.


http://www.4shared.com/document/IqpHQm7h/Mercruiser_Service_Manual_7_GM.htm

 

[synergy141]

Re: engine only runs when hook up Pos terminal of battery to Purp wire on startersole

anyone know how to measure the voltage at the coil?

 

[Bt Doctur]

Re: engine only runs when hook up Pos terminal of battery to Purp wire on startersole

You jumper is powering the pump from the coil.there is a pressure switch for the fuel pump mounted just above and foward of the oil filter.

 

[synergy141]

Re: engine only runs when hook up Pos terminal of battery to Purp wire on startersole

is that the same thing as the oil pressure switch or completly different?

 

[dubs283]

Re: engine only runs when hook up Pos terminal of battery to Purp wire on startersole

yep

oil pressure switch - only allows the fuel pump to run when oil pressure is above 3 psi - or when cranking

check the wiring diagram - it will make sense

 

[synergy141]

Re: engine only runs when hook up Pos terminal of battery to Purp wire on startersole

I used a test light on the ignition coil and no light came on while the key was turned on. I replaced the ignition switch*, still does the same thing

 

[Bt Doctur]

Re: engine only runs when hook up Pos terminal of battery to Purp wire on startersole

no reason to start throwing parts at it, it was running ,correct? .so why replace the coil????
follow the power.
system power comes from the smaller red wire on the starter, then thru the circuit breaker, thru the main harness plug, thru main harness to dash ,thru ign switch, back to the + side of the coil.may go thru a safety lanyard switch also.
http://www.boatfix.com/merc/Techbk/96/96HGD4.PDF

 

[synergy141]

Re: engine only runs when hook up Pos terminal of battery to Purp wire on startersole

*edit, sorry I replaced the ignition switch, not the coil

 

[dubs283]

Re: engine only runs when hook up Pos terminal of battery to Purp wire on startersole

you NEED to follow the link for the downloadable manual in an earlier post

it has wiring diagrams that are key for solving your problem

look into the wiring for the fuel pump - starter solenoid and oil pressure switch