CAT 304.5 - Will not shut off - Bad alternator?

[skymoco]

I have a CAT 304.5 with a odd problem. Sometimes it will not shut off. I've tried disconnecting every relay, the ignition switch, just about every other thing I could find. At first I had to stop it by pulling wire to the fuel shutoff, then I figured out the circuit breaker to the console would stop it, and finally if I pull the bulb to the alternator light that will do it.

I'm thinking that my alternator is bad, and that somehow, when it's running it sends enough power back through the bulb to keep the main power relay energized.

Before I spend a couple hundred on a new alternator, does this sound right?

 

[01DUALLY]

Does it maintain a charge if you have a load on battery lights etc ? Try turning lights on while engine is running then diconnect positive side of battery. If alternator is bad the lights will dim eventually and machine will shut down. This may take some time before it shuts off. Not sure if this trick works with every machine but worth a try.

 

[joispoi]

Does your machine have a cab or open ROPS where the ignition switch might be getting water in it?

 

[skymoco]

Does your machine have a cab or open ROPS where the ignition switch might be getting water in it?

What's actually going on is that the connection for the alternator (not the power connector, but the two little wires) has cracked with age and the two wires were touching. When that happens, it somehow allows enough power to flow back that the main relay stays powered with the key off.

Now I need to find a pigtail with a new connector.

 

[joispoi]

Glad to hear you found your gremlin.

 

[NCPIPELINE]

Interesting problem, glad for the info.

 

[Plumberboy76]

I have a similar problem, but for starters my 304CR will shut off pretty often and that gets annoying. Fuel filters, air filters are all good. Occasionally the machine will not shut off when I want it to????Any ideas? I will post this question in a new thread also. Thanks

 

[NCPIPELINE]

Fuel Solenoid.

 

[Plumberboy76]

Replaced fuel solenoid and still have same problem, what controls the fuel solenoid

 

[4x6HeavyMetal]

Most fuel solenoids are de-energized while the machine is in operation. This saves having an energized solenoid the whole time a machine is running. The solenoid would just draw energy eventually getting warmer and warmer. Not efficient. Anyway, when the operator switches the ignition key to the off position then the fuel solenoid timer is actived for a short time...like five to ten seconds energizing the fuel solenoid which in turn shuts off the flow of fuel. In case you have replaced the solenoid and the problem still exists then check the terminal at the solenoid with a voltmeter just as you switch the ignition off. Battery voltage should be present for several seconds. If no voltage then I would locate the fuel solenoid timer and/or associated wiring. Best of luck!

 

[Lil' Puss]

ignition switch - key switch. If the plastic connector fails, and the sense circuit (red wire) touches the field circuit (white wire) the alternator will continue to charge.

 

[Lil' Puss]

I might add that on all the fuel shut-off solenoid valves I've seen the coils are rated for a 100% duty cycle, which means they are energized as long as the key switch or power source is turned on, engine running or not. Some engine manufacturers will have an oil pressure switch used in conjunction where an electric lift pump is employed so the lift pump will not operate unless there is oil pressure - in this instance there is an automatic override to allow for starting.

 

[Lil' Puss]

Now I need to find a pigtail with a new connector.

Local auto parts store, about $6.00.