I emailed with Speedhut, they “think” it will work. I guess there is only one way to find out. I can always switch back to the original dash
It wasn't the alternator
- Thread starter 01yellercobra
- Start date
I’m dealing with a bit of an alternator issue now myself. After driving a bit the car will idle at like 12.7-12.9 volts but once I start moving it goes up. I did the big 3 upgrade and a 130amp PA performance altenator back in 2020. Probably going to just do a KMJ and be done.
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That sounds like an alternator on it's way out. Personally I'd go another route for an alternator. Talk to PA about getting it rebuilt. Or get it rebuilt locally. A lot of times you can find the parts online and do it yourself.
I'm still chasing mine. Found another issue yesterday that might be causing it. But I need to find a good wiring diagram to be able to check it better. My shop manual doesn't have the detailed schematics.
If anyone has the wiring diagrams on PDF that would be great. Prodemand doesn't have the fuse box under the dash available.
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granted mine is a different alternator with the 4g and mounted in the valley but I've not had good luck with alternator output at idle when heat soaked from J2F or KMJ. If the PA was good before Id have them or a local shop redo it as mentioned.
Once I swapped pullies on the KMJ it did decent. Honestly, looking at what I've found the alternator itself is probably still good. It's just all the experience I've had that makes me look elsewhere. The J2Fab was solid until the regulator started acting up. And even then it never fully failed.
I have to double check my alternator pulley size. I can’t remember which one is in there because this was 2020 when I did this, but I do know that I did the research and used that chart that’s floating around. Problem is once I did the alternator on my car it melted 3 pistons shortly after lmao so the car basically sat from then until this past December. I’m concerned the 130amp isn’t enough. I never had issues with alternators or voltage before I did the whipple swap and the dual 430 pump return set up.
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I had the 3" pulley that was recommended to me. The problem was at idle I would see 12vdc. And naturally everything dipped with that. He recommends that size to keep the WOT RPM for the alternator down. I swapped to a stock size pulley and I would see 14.5-6 at cold idle. It might drop to 14.0 once hot. I figured the couple seconds it was overspun at WOT would be worth better charging down low.
just a thought, for those that have an issue and did the big3 upgrade, did you replace the power wire or run the new one on top of the factory? knock on wood but I have the 250kmj for about a yr and don't see these issues with replaced wire.
I ran the upgraded wire parallel to the stocker. It's been like that since 2019 I think and it's been fine.
what do yall mean by this? Are you saying you put the stock alternator wire on the alternator AND the upgraded power wire goin to the fuse box and then to the battery?
it means he didn't replace the original wire and just connected the new one on top of the factory wire. In my case, the factory wire was removed and replaced with the wire from the big 3 kit. To do it this way, you have to make a connection change at the fuse box but I think its cleaner and eliminates another potential issue. The instructions have both ways listed.
I have the big wire with the fuse running between the alternator and fuse box. I also have the stock wire with the fusible link connected to the alternator and fuse box. It's overkill, but I prefer it that way.
I have a shorter upgraded wire running between the fuse box and alternator. Then a fat ground wire running from the alternator bolt to the negative terminal on the battery. As well as an upgraded ground running from the negative terminal to the ground on the core support.
Next time I have the time I’m going to see what size alternator pulley I have on my car. I also really want to do a Hobbs switch for my pumps and do it so they both don’t run at the same time. I’m not sure if that would maybe help, but I know that’s how Fore recommends it be set up.
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Is it the 3"?
It would be interesting to see what your voltage is at idle. With the 3.0" and stock lower mine would dip into the low 12's. To be honest if I wasn't watching it I probably never would have noticed.
Interesting. I guess you got a better alternator than I did.
That would be great, so far so good. I do have a new battery and only other difference from some is the big3 with the factory cable replaced. Not sure if any of that makes a difference.
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