Low FICM voltage

[Wyoming6.0]

So I've been monitoring my FICM voltage with my scangauge ii for about 2 mo.the or so. A while back my truck died. I ended up having a bad IPR valve. While replacing it my batteries died. Over the past month or so I noticed my FICM voltage has been dropping during cold starts. Just while I'm waiting on the glow plugs. Tonight I seen it drop all the way to 26 volts. As soon as the glow plugs quit it starts climbing again goes back to 48 volts. I also noticed that at WOT the volts will start to drop too. Haven't seen below 44 volts yet. My guess is I should replace my FICM before I start ruining injectors and all that. But I wanted to get your guys opinion before I do that. Oh, I haven't had my batteries checked yet. Could that be the problem?

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[kinnisoj]

If you wanna learn a TON about the FICM give Ed at FICMREPAIR.com a call. That man is a wealth of info.
He fixed my ficm and truck runs 100% better

[mhatlen]

Yea it's time to deal with the ficm before truck leaves you walkin.
Good time to look into getting a larger alternator on the truck too, will keep you from going down this road again. 48 volts all the time all temps and speeds is what you should see, a occasional momentary drop to say 47 or even 46 is acceptable when first startup but 48 is the magic number.
Good Luck with it and look into a new alt well worth it on these trucks.......

[ldhost1]

What do you guys suggest for an alternator?

[ZMANN]

DCpower ,,,,,,,,

[mhatlen]

x2 We both went with 190 amp, batteries have more bite......

[PSDMikeB]

I just put in the DC Power 190. Performs as adevertised - my stock alternator was putting out about 80 amps at initial start-up (less than the glowplugs were using) and the voltage was sagging way down (less than 12 volts while glowplugs were running).

New DC 190 puts out 140 amps at idle (as they advertise and as I verified) so it covers the glowplug draw and about 40 amps more - keeps the the voltage up over 12 even with glowplugs running.

MikeB

[ldhost1]

Thanks, any brands you recommend?

[mhatlen]

Ok that is kinda funny, :the brand is: (DC Power) you can look them up on Google.

They have all different alts for sale, if your truck is stock and you do not have a big stereo or lights ect a 185 amp would do fine if you want 140 amps @ idle go with the 190 amp model.

Make sure you get the spacers if you do go with the DC Power brand. The pulley is 1" smaller so it can make more power at idle but it can leave the serpentine belt a little on the loose side. (1/2 round stock spacers)

BTW I paid $335.00 for the 190amp, IIRC the 185amp was $285.00 but not sure.
Anyways have heard nothing but good about them and they are 100% USA........