4.3LX won't start

[ctak]

Well I'm back at it again. A while back the engine died and the symptoms were that the engine would fire for a short time then die. I ran through all the wiring and found out that the oil pressure sensor was bad. To test this I jumpered around the sensor and when I turned the key to the "on" position I would hear the electric pump clicking. Today the engine did the same thing again. I thought OK I'll just jumper around the sensor again. But this time after jumpering and turning the ignition to "on" the electric pump wasn't running. I ran a test light to the wires and neither of them were getting any juice. Does anyone know where the power comes from prior to the pressure sensor? Does it come from the ignition switch or somewhere else. I've traced one wire to the coil and to the round connector going to the ignition. Another one goes to the alternator. Which one should active when the ignition switch is turned on? Any help would be appreciated. Thanks.

 

[petryshyn]

Re: 4.3LX won't start

is this a fuel injected engine?

 

[ctak]

Re: 4.3LX won't start

No it has a weber 4bbl carb.

 

[hondon]

Re: 4.3LX won't start

Purple wire is key on power to the unfused portions of this ignition system.

 

[ctak]

Re: 4.3LX won't start

If the purple wire is key on power to the engine and components then I will disconnect the purple wire from the coil, alternator, and power pack and jumper across the oil pressure switch to see if I have power. If I still don't have power could it be a bad ignition switch? The engine was running in a slow troll when it died.

 

[ctak]

Re: 4.3LX won't start

I'm getting some pretty confusing readings. I disconnected the purple wire from the coil inputs, also disconnected the purple wire going to the starter solenoid, jumpered the oil pressure purple wires together. Turned on the key and nothing. When I took a VOM and measured the resistance between the purple wire and engine block ground I get only about 1.2 ohms. Shouldn't there be more resistance between these two? Also a funny thing when I started probing around I could get the same readings between the hose clamps on the cooling system and the purple wire. Aren't the hose clamps isolated by the rubber on the hose? I'm kinda confused and really don't know what to check next.... Any suggestions very much appreciated.<br /><br />

 

[hondon]

Re: 4.3LX won't start

Keep in mind that you have two oil pressure senders with this electric fuel pump.One on top in the usual spot and one near the oil filter that when open denies voltage to the fuel pump.That purple wire should give you battery voltage at all points after the key is turned on.

 

[ctak]

Re: 4.3LX won't start

When I turn the key on I can't get any voltage on the purple wire. I'm wondering if it is grounded somewhere or if there is something wrong with the ignition switch. If I disconnect the wiring harness connector and check the no. 5 pin it should have 12v with the key on. If it doesn't does this indicate a bad switch?

 

[ctak]

Re: 4.3LX won't start

OK, I've disconnected the wiring harness connector. When I turn the key to the on position I get a short from pin 6 (12v) to pin 1 (gnd). Any ideas where this could be coming from? I checked the ignition switch and it's working OK.

 

[ctak]

Re: 4.3LX won't start

Finally traced the problem..... checked the wiring up at the console and found that the kill switch wasn't working. I didn't realize that the motor would crank if the switch was activated. Again thanks for all the suggestions. This is a great resource..<br />