I may not explain this good but here goes. I need to test the alt for feed back, my apps or something is causing it to feel like its running out of fuel. It doesn't cut out hard, it has that running out of fuel feel to it. The more you mash the pedal no help its dead, let it all the way up then start back into it and it will either accelerate or you have to let it up again then it will run ok. It may run all day and never do it again or it has done it 1/2 dozen times. No codes, well it has a 1693 but nothing in there. I have put three diff. apps on and they all do the same.

Fuel filters are clean, fuel pressure is 15. I just cant find the write up.

Thanks

Put your meter on AC volts, put red on the stud coming out of the back of the alternator and black on the battery ground terminal.

P1693 code means there is other codes present. Might need a better code reader.

 

Ronman got the alternator test right on the money. Make sure your volt meter is capable of small voltage on the AC side like 2V or 200mV.

Ok on my meter it has ACV 750 OR 200. On 750 it reads 029  On 200 it reads 30.2   
I have no idea what that means, this is a cheap meter, I have a good one at the shop that is a better meter. Can anyone make since of this?

Not low enough scale and the meter can calculate small voltage numbers. The meter has to have either 2V or lower setting. You current meter is designed for 200V and 750V AC but doesn't have the ablities for small voltages. You going to be measuring 10mVAC to about 50mVAC (Millivolts).

Bad grounding of the alternator causes additional AC noise and so does bad grounding to the engine, truck frame and truck body from the batteries. On mine I found that the painted alternator mounting bracket was causing a poor ground to the engine block so I ran an added ground from the alternator housing to the battery. To check for a poor connection in a ground you use the OHM meter. Batteries should be disconnected because any voltage being sent thru the wiring during a test will damage the volt meter on the OHM setting.

On the volt meter set for OHM's, take the two probes and touch them together to learn what it should read with a good clean connection. Should say Zero OHMS on good clean contacts and good clean grounding paths in the wiring.

Very basic stuff here but it's difficult for some like me who have to rethink the basics again and again to test things properly.

I have a better meter at the shop, I think I remember it has lower settings. Thanks for the reply's, I will get back with ya tomorrow afternoon.

Another note that is commonly missed. An alternator may read within spec at idle, but be out at RPM.  Either use the Max function on your meter or have a friend (I have no friends) sit inside and slowly rev up (I went to 2800ish) and then back down to idle.  

Other factors can be temperature and load.  When it is super hot out and you're asking the alternator to power lights, ac, radio, inverter, etc. it will get WAY hotter than normal.  

 

If you have a lousy ground, or a a bad lead going to the battery (the factory one is quite small for trucks with extra electrical demands) you can also build extra heat in the alternator.  

Ok I got my other volt meter and set it at 4 volts acv and ,o30. I also ran the heck out of her today, I pulled 34k with the ac on and lights on for about 15 miles. I mean I had my foot in it 21lbs boost all most all the way 1-1100 egt and she's stock. And it never missed a lick ran good. Go figure