[larrygaither]

After soaking the top of the engine several times with diesel fuel from a leaking fuel filter I have had no problems until the most recent. After starting the engine now it takes a good 5 minutes for the alternator to start charging. Is this normal, my vehicle is a 2001 Excursion 7.3 psd? After it starts charging it does fine until I turn it off and then start it again.
Thanks

 

[redcell6613]

I found this kind of interesting. It's from ARCO Systems Alternator Tech Bulletin:
I never knew this but I suppose it makes sense......

Just because the alternator looks like it’s turning, doesn’t mean it’s turning fast enough to charge. Most
alternators do not start charging until they reach 1,000 RPM alternator shaft speed. 5,000 RPM alternator
shaft speed is normally required to reach maximum output. If you’re not sure what the alternator shaft
speed is, you can determine this with the pulley ratio. Measure the diameter of the crank shaft or drive
pulley and the alternator pulley. Divide the crank shaft pulley diameter by the alternator pulley diameter. This
figure would be the engine-to-alternator RPM ratio. A normal ratio would be 2.5 to 1. For example, let’s say
we have a 7 inch diameter crank shaft pulley and a 2.75 inch alternator pulley. We would divide 7 inches by
2.75 which equals 2.54 to 1. If the engine was turning 1,000 RPM we would multiply 1,000 by 2.54 which
would give us 2,540 alternator RPM.
Again, with today’s high amperage alternators, belt condition and tension are critical in proper
alternator performance.

 

[larrygaither]

Thanks Redcell, but my problem seems to be regardless of the rpm the engine is turning. It does the same thing for the same amount of time whether I am going down the road or sitting in my drive at idle. The voltmeter shows 11.54 volts for the first 5 minutes or so.

 

[normanpaul]

I think what you are seeing is normal for these trucks, I have a volt gauge in my truck and my buddy's 99 both have 6 speeds. If you have issues like slow cranking or volts dropping below 9 volts while cranking check and clean all battery terminals and grounds. My volt gauge only climbs to 14 volts a few months out of the year when i don't run heat or ac.

 

[444-4D]

The voltage won't immediately jump to 14.4 after startup, the glow plugs use too much current. Once the glow plugs turn off the voltage should increase. If the voltage is low after they turn off, I'd make sure both batteries are good.

 

[larrygaither]

Thanks guys, bought 2 new batteries Wednesday. After the charging system kicks in after 4 or 5 minutes of run time every thing is fine.