Mercruiser 4.3 lx gen2 2bbl fuel problem

[kcitrin]

I have a 1997 Regal Destiny 200 4.3lx Gen2 with 2bbl carb. Out of the blue the fuel pump doesn’t run. I have done the following trying to find the problem. It will run going directly from the battery to the pump. Bypassed the oil pressure switch and got no power to the pump. Ran power to Purple/Yellow wire at the oil pressure switch and fuel pump worked. I need help finding the issue as I’m not sure what else to try. I think by putting power to the Purple/Yellow wire at the oil pressure switch it eliminates the starter solinoid since the pump gets power... of course I could be wrong in that assumption. Anyone have any other test ideas? Any help would be greatly appreciated!!

 

[alldodge]

Turn key to ON and measure voltage at the oil pressure switch, one side (purple) should have 12V on it. Also check for 12V on the + side of the coil

 

[kcitrin]

Thanks I will check that tomorrow. If it doesn’t have 12 v then the issue is the alternator?

 

[alldodge]

Trying figure out why it didn't run the pump when you bypassed the oil pressure switch. One side is feed by the key switch, so when its turned ON it should be there. If its not there then there is a break in connection.

The purple wire goes to the ALT field winding's, the coil, oil pressure switch

THe pump should also be feed from the starter as you mentioned, and that could be from a problem in the starter solenoid

 

[kcitrin]

Sorry this took so long to test! So I did test the purple wire from to the oil switch with the key on and there was 0 volts.... then tested the orange wire to the alternator from the starter and it had 12.49v. Tested the Alternator where the Purple wire connects and it also had 0v. So based on this I am leaning towards an alternator problem... do you agree? What other tests should I do?

 

[alldodge]

With the key ON there should be 12V on the purple wire, the key switches power to the wire

When connecting battery directly to the pump your back feeding the ignition

Here is what I'm reading is the issues
Can turn the key to start and the motor cranks but does not start, reason is the fuel pump is not running. The starter does not supply power when cranking to the Purple/Yellow wire

So power makes it to the key switch and back to the slave relay on the Yellow/Red wire from the key.
Power makes it thru the 50 amp breaker because starter will crank

Power is not going to the purple wire.

Purple wire connection could be; Bad key switch, bad connection on kill switch to 10 pin connector or bad kill switch or broken purple wire

Purple/Yellow wire could be; bad starter solenoid internal connection, or bad wire cnnection

Do the gauges turn ON when key is turned ON?

 

[kcitrin]

The gauges do turn on with the key in the ON position. I tried to run a jumper from the alternator to the purple/yellow wire at the oil switch and the key ON and still got nothing. Will check the kill switch next.

 

[Rick Stephens]

Sorry this took so long to test! So I did test the purple wire from to the oil switch with the key on and there was 0 volts.... then tested the orange wire to the alternator from the starter and it had 12.49v. Tested the Alternator where the Purple wire connects and it also had 0v. So based on this I am leaning towards an alternator problem... do you agree? What other tests should I do?

The battery supplies voltage to the ignition switch, the ignition switch then, through the purple wire, powers the coil, choke and oil pressure switch. NO, the alternator is not the fault - your alternator just charges the battery. It has ziltch to do with purple wire not getting power.

 

[kcitrin]

Is there a way to bypass the kill switch to test?

 

[alldodge]

Is there a way to bypass the kill switch to test?

Yes, run a jumper from the key switch to one of the gauges

 

[Edroberts55]

I have been reading this thread to figure out what the purple/yellow wire from the starter solenoid does. I bought a new solenoid and it does not have a terminal for the purple/yellow wire.

Maybe I am wrong but here is my understanding:
While the solenoid is energized 12 volts is passed to the purple wire terminal to power the fuel pump via the oil pressure switch. The engine starts, the solenoid is de-energized after which the purple wire gets 12 volts from the alternator.

 

[achris]

Hello and welcome to iboats.

Please start your own thread if you have a question.

Chris...
iboats mod team.