Charging issue with my 3400

whiteretta · Post by **whiteretta** » Thu Aug 14, 2014 11:46 pm

My 3400 seems to have a charging issue, primarily with my lights on.

While moving, the car was running about 13.5 volts. When coming to a stop I drop down to about 11 volts. Keep in mind, I have new positive and negative battery cables with a good battery at this point in time.

My alternator was under warranty, so I went ahead and swapped it out along with finally finishing the big three. I also made sure to use a nice thin coat of dielectric grease on all the electrical connections.

First drive went great. Constant 13.5 volts, even with all the lights, including my aftermarket fog lights. Next time I drove it, the problem was back again.

I have no problem testing wiring and components, but where should I look next? I haven't verified good connection on my battery cables at the ground and starter, but I have excellent cranking.

Ideas?

Ramborogers44 · Post by **Ramborogers44** » Sat Aug 16, 2014 11:15 am

well with your car running it should be putting out 14-16 volts, but i would check the alt. fuse if that is good make sure all of your fuseable links are good( there the wires that run from your starter to the alt they are bad about breaking over time)

Post by **3X00-Modified** » Sat Aug 16, 2014 11:52 am

whats your idle and do you have an underdrive pulley?

whiteretta · Post by **whiteretta** » Sat Aug 16, 2014 8:47 pm

My idle is at about 700 RPM, and I do have an FFP pulley.

1988GTU · Post by **1988GTU** » Sat Aug 16, 2014 10:28 pm

Its not sensing rpm/load due to the udp and set idle speed.
you will want to increase the alt pulley dia or create a load device to implement charging at lower speeds, if applicable.
More than likely you will need to have an alternator altered to meet your needs.

whiteretta · Post by **whiteretta** » Sun Aug 17, 2014 12:33 am

Interesting... Is this why some companies also offered a lightweight alternator pulley, or does that simply function as reducing weight?

1988GTU · Post by **1988GTU** » Sun Aug 17, 2014 7:41 am

whiteretta wrote:Interesting... Is this why some companies also offered a lightweight alternator pulley, or does that simply function as reducing weight?

Functions as reducing weight & your discretionary income.

whiteretta · Post by **whiteretta** » Sun Aug 17, 2014 9:26 pm

Well that just about seems like a waste then, lol.

I'll have to do some research and find a larger pulley for the alternator. I looked into other alternator options, but can't find anything with more power that has the same mounting brackets.

Post by **3X00-Modified** » Tue Aug 19, 2014 6:46 am

Larger pulley basically eliminates what the underdrive pulley is doing. The gains are so small on those vs the chance of damage to the valve train it's not even worth running a UDP on the 3400 engine.

No dampener is not a good thing.

whiteretta · Post by **whiteretta** » Tue Aug 19, 2014 8:42 pm

Thanks for the info... Probably why not a lot of people run them.

SummitBalt08 · Post by **SummitBalt08** » Wed Aug 20, 2014 12:55 pm

When I bought Andys old 3400 Aqua Z26 .. it had the UDP on it..

That thing was annoying as hell..

At stoplights the gauges would dim at night and all kinds of stuff..

Once you put a stock pulley on there its much much nicer lol best thing I ever did to that car.

Still sucks that I had to sell it though

whiteretta · Post by **whiteretta** » Thu Aug 21, 2014 11:18 pm

I did some better research, smaller pulley = faster spinning alternator, so... Better charging.

Not a lot out there for our style of alternator with an external fan though!

Post by **3X00-Modified** » Fri Aug 22, 2014 6:02 am

Yes of course but the smaller crank pulley made everything slow down so putting a smaller pulley on the alternator will speed it back up and defeat the purpose of the UDP... Hence my point before is it really worth it now since all that your slowing down is the water pump and power steering...

1988GTU · Post by **1988GTU** » Fri Aug 22, 2014 9:09 am

Better off just going manual rack, losing the A/C and all it's parts, while keeping the stock pulley.

The only benefit for the solid aluminum UDP is the ease of removal with no risk of separating the rubber from the pulley ... since the udp is not dampened.

Post by **3X00-Modified** » Fri Aug 22, 2014 9:24 am

Buy a proper harmonic balancer puller and you'll never separate the rubber from the pulley

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