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1992 F150 Voltage Drop

Kaajot

Micro Machine Manager
I can take some pictures of the trucks and connections if you need them tomorrow.

Funny thing, I went back and looked at my 92 flareside project truck, it's 3g.
the 93 flareside sitting next to it that was my son's is 3g.
My 94, the 94 Cantorian, and my 95 Eddie Bauer are all 3g.
You must have ended up with a "parts leftover " truck.
post the build date off the door please, this one has me stumped1

It's a 1991 build date, sold as a 1992 "Custom." So I guess it's kinda like the 2014 Mustang leftovers they converted to 2014 Warrior Mustangs to sell to Soldiers in Afghanistan. I always wonder why they differentiated between Flareside/Lariats and Customs in same years and engines/transmissions.

I'm guessing this is the answer.

I'll be shopping tonight. Guessing the alternator is NOT going in tomorrow. :p
 

dustybumpers

don't play well w others
No, you have some soldering, and taping to do

In the end, you will be glad you did it.

Oh, and my wife said she wants the last truck done now too, so I have an alternator on the way from rockauto. guess I'll have pictures...….LOL
 

dustybumpers

don't play well w others
Custom was a truck from 80-91. I guess you got a left over. LOL
The xl replaced the custom.
 

Kaajot

Micro Machine Manager
No, you have some soldering, and taping to do

In the end, you will be glad you did it.

Oh, and my wife said she wants the last truck done now too, so I have an alternator on the way from rockauto. guess I'll have pictures...….LOL

That's awesome! smiliegitrdone

I'll take pictures of the soldering and taping and kinda show my process. I'm pretty good on documentation (Aviator/military/data analytics training & IT Contractor experience).

May the odds be ever in your favor! :)
 

dustybumpers

don't play well w others
where you really see the difference, the frame rails in the front on 91 are straight

the frame rails on 92'96 are crimple, to bend in an accident ( air bag trucks)
except the diesels, and 460's they kept the straight frame
 

dustybumpers

don't play well w others
Oh, and which alternator did you buy?
The 95 amp uses your stock belt. The 160 amp, that's the one with the 180* mounts. ( straight up and down, and huge)
Uses the belt for a 94 f150 with a 5.0.

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Kaajot

Micro Machine Manager
Oh, and which alternator did you buy?
The 95 amp uses your stock belt. The 160 amp, that's the one with the 180* mounts. ( straight up and down, and huge)
Uses the belt for a 94 f150 with a 5.0.

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Just spent $600 between dogs, hydroponics, and alternator conversion stuff (ebay/amazon). I'm spent.

The Alternator I got -- forgot, there's a core charge, woohoo -- is from Advance. It's Stock #7761A by CarQuest, 130amp. It's for a 1995 F150, hoping it'll fit. Has mounting positions at the 12 and 6 position. May need a new bolt and spacer to make the gap solid, and I know there could be some grinding involved to get it to slide into the framing mount inside the truck.

I got it from there because it's one of those things you don't want to wait for on the road and Advance is everywhere, plus Carquest and the other main brand they carried have a limited lifetime warranty whereas the RockAuto only had 1-2 years pending the brand. Better brands, lesser warranty. Figured it was worth the lesser brand with a better warranty and faster turn-around to replace.
 

dustybumpers

don't play well w others
The 6 cyl mount takes both style alternators.

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Old_Paint

Old guy with old cars
225
29
Alabama
The shortest answer is to take the alternator off the truck and take it to your friendly neighborhood parts house and get it tested. Then you're standing in front of the counter when they tell you it's shot. If the battery is staying charged, I wouldn't worry too much about a dip in voltage at idle speed, especially if you've got the HVAC fan running, the lights on, and the ghetto blaster rattling the windows. I have a manual transmission, and sometimes bog the engine down a little when backing or whatever. Not uncommon if the engine speed drops below 800 RPM to see the alternator output droop a little. I still have the original factory 2G in my truck. Unless you're adding a bunch of electrical load to that truck, I don't think I'd bother with changing to a 3G. It's an easy enough conversion, but if you don't need the extra output, it won't really help you with anything but bragging rights.
 

Kaajot

Micro Machine Manager
The shortest answer is to take the alternator off the truck and take it to your friendly neighborhood parts house and get it tested. Then you're standing in front of the counter when they tell you it's shot. If the battery is staying charged, I wouldn't worry too much about a dip in voltage at idle speed, especially if you've got the HVAC fan running, the lights on, and the ghetto blaster rattling the windows. I have a manual transmission, and sometimes bog the engine down a little when backing or whatever. Not uncommon if the engine speed drops below 800 RPM to see the alternator output droop a little. I still have the original factory 2G in my truck. Unless you're adding a bunch of electrical load to that truck, I don't think I'd bother with changing to a 3G. It's an easy enough conversion, but if you don't need the extra output, it won't really help you with anything but bragging rights.


Welll, I already got the 3G and all parts except the little red connector for the battery terminal (think I can manufacture something from the local parts shops).

The other thing is, the voltage drop happens with all electronics off whenever I put it into gears. And it goes to minimal power when in park/neutral/drive with brake pressure on and turning the wheel (power steering pump engaged) left and right. And the voltage drop was locking up at minimal indicator, but this could all be alternator issues and may all fix themselves based on a new alternator.

I'll take the old one to the parts store, but they want it for the core charge anyway! :) $40 in my pocket when that's done.

Appreciate the confidence that I'm probably not draining the alternator's power supply though! The 750 Watt Amplifier is the biggest draw. I don't even have a compressor/condenser to run (no AC). In Arkansas I would just run the alternate 2-70 AC unit (2 windows down, 70 mph). In NY, not as necessary and 70 mph hasn't been seen in quite some time. HOWEVER, may be able to hit 70+ mph soon :) :guns:
 

Kaajot

Micro Machine Manager
Oh, and which alternator did you buy?
The 95 amp uses your stock belt. The 160 amp, that's the one with the 180* mounts. ( straight up and down, and huge)
Uses the belt for a 94 f150 with a 5.0.

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Did you mean 130 amp?

We took a look -- the alternator pulley is different (bigger) than the gen 2.

Does this mean all my belts are useless? :-( Can we transfer the pulley to the new alternator, or do I need to buy 4 more new belts? (Spares) Just bought 4 Serpentine Belts for the current pulley configuration.

Still waiting on the 3g 6g battery terminal connector and the 2 AWG wiring and then we're ready to do the whole mod, except the pulley is technically wrong on the new alternator.

EDIT: Took a look at the belt size being just about 2 inches larger on both 1994 and 1995 5.0L, so this makes sense. Ordered 2 cheapo ($8) belts to avoid changing the pulley and voiding the alternator warranty plus causing extra maintenance in the event another alternator has to be installed. Better to just use the larger belt for the larger pulley it comes with!
 
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dustybumpers

don't play well w others
The pulley can be changed, just not with the fan.....
No fan on 3g.

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dustybumpers

don't play well w others
I'll be doing one tomorrow, so I will do pictures.

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Kaajot

Micro Machine Manager
The pulley can be changed, just not with the fan.....
No fan on 3g.

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I did an edit up on my question.

The belts (1992 4.9 to 1994/1995 5.0L) are about 2 inches larger going to the 5.0L, which makes sense with the size increase with the pulley.

I'm inclined to just know I have to use a different belt rather than modifying the alternator and "voiding" the warranty by changing to a smaller pulley, particularly in case the alternator fails and in order to warranty it I would need to pull the small pulley off for next alternator AND put a larger pulley back on.

They all assume there is an air conditioning unit in the 5.0 it seems, but I don't have that pulley (no AC). However, it does seem to be the right length at only 2 inches longer to wrap around the larger pulley. Is that correct?
 

dustybumpers

don't play well w others
Not sure, I assumed you had a/c too. I'll look it up in the morning.

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Kaajot

Micro Machine Manager
Hey Dusty, any advice on the belt length vs pulley?

I mean, if the pulley can be changed without voiding the warranty, I reckon that would be ok too. However, I've got two very cheap $8 belts coming for a 1994/95 (same) 5.0L and it's about 2 inches longer, which looks TLAR by Mark 1 eyeball (That Looks About Right). Of course, it could be too slack too given it's just a slightly bigger pulley stock on the 130 amp Gen 3 Alternator (maybe 1-2 inches larger in diameter).
 

dustybumpers

don't play well w others
Take the belt that's on your truck now, and hand it to the counter person. Tell them you need a belt 1/2" longer. He can read the number and do that. Belt tensioner can make difference back or forth an inch.

Save the sleeve if it works so you know what to get next time

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Kaajot

Micro Machine Manager
Good news! Put new alternator in, put 5.0l belt on. Good n snug wi hour being too tight. Ran it and didn’t fall off. Have spare too, just in case. Did not change pulley size so I can go replacement alt to replacement alt.

Have not finished yet the wiring (just did a battery start). Cut the ignition harness and will have the small wire in shortly, but took the alternator out because I’m having an issue seating the in-line fuse wire with the adapter end onto the back of the alternator.

Am I supposed to just tighten a lug on there if I can’t make it work? There is a plastic connector over the terminal presumably as a water guard.

Attaching photos of my wiring and the connector I’ve already semi-snapped off (the eBay $7 one). And yeah then 2 gauge in-line wiring could be a little shorter but it’s done and crimped and shrink wrapped so if I can make that work, great.

Any advice about the in-line? Or is it supposed to connector the starter solenoid?

Also, can I remove the other two wires now? Looks like they go to the starter solenoid once I unbolt that’s wiring set in the right nutt, but that’s the last thing I want to do before hooking up battery. Want to finish this alternator wiring issue first.

Mechanic already left, I’m just trying to get the conversion done. Gonna do the little wire connector and hopefully find the info but any replies in next couple hours will help greatly!
 

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dustybumpers

don't play well w others
For whatever reason on this last alternator I just finished, I had the same issue. So I ground down the sides of the copper until it fit in there. Put the yellow wire on top, and tightened it down.working fine.
Sadly I didnt get that picture.
I got the rest though
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