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Thread: Charging Problem OR Too much power usage

  1. #1
    Half Throttle
    Join Date
    Apr 2007
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    350

    Charging Problem OR Too much power usage

    Need some insight-so I know how to proceed here. No one knows these cars like you guys do-so lets see what works!

    Problem- Car doesn't have enough power to start after its been running.-depending on how long I idle and my mixture of driving/ avg RPMs. The starter will click, but not be able to turn over.

    I think I may need a larger amp alternator-such as a 140 or 150. I added up my amp usage using a calculator and I show 115. MY grounds have been checked and redone. No shorts on the car etc.

    Car dips into reserve battery storage-by what Ive learned- into the 12's while driving.
    Under acceleration I hit 13v but usually cruise in the 12.5-13.5 range. Rarely am I in the high 13's or 14v's.

    I probably could upgrade to a better battery-less internal resistance-such as an optima or best NAPA.

    Knowns:

    1. 105 A. alternator tested fine.
    2. Battery is good. Passed a several stage test.
    3. Starter is good.
    4. Car always starts from a cold start.

    To add to the mix:
    1. I increased the belt length when I added a supercharger.
    2. I currently have an underdrive pulley on the crank. I DID run an underdrive pulley on the alternator but since went back to stock size pulley on the alternator and it seemed to help a little.

    Major Electrical
    1. Megasquirt
    2. PIAA Halogen headlights
    3. 255lph fuel pump
    4. MSD DIS 4-currenlty waiting to reinstall new one but my last one fried-I believe b/c of low voltage. The coil interface arc'ed badly.

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  3. #2
    Light Throttle
    Join Date
    Aug 2013
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    111
    Sounds like a heat soak issue. If it always starts cold and only struggles when hot, I would look at buying/creating a heat shield for your starter.

  4. #3
    Half Throttle
    Join Date
    Apr 2007
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    350
    I initially thought the same thing. I installed a heat wrap on the starter and checked the grounds/wiring at that time.

    Is it possible that the alternator is getting heat soak from a radiator line that I have draped over it?. On a 3.4 that line typically goes under the alternator, however the blower sits there now.

    Could a longer serpentine belt cause the system to charge slower-or the pulley to not spin fast enough on the alternator? I installed a much longer belt with the blower.

  5. #4
    Full Throttle Extreme!
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    Apr 2007
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    A longer belt will have no effect on the rpm's of the pulleys. I had an underdrive crank and alt. pulley on my 3.4 and had charging problems. I ended up keeping the crank pulley and putting the original alt. pulley back on and still had problems. To fix the problem I put an overdrive pulley on the alt., unfortunately they don't sell them anymore where I bought it. I eventually installed a 140 amp on my car and have no charging problems.

  6. #5
    Half Throttle
    Join Date
    Apr 2007
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    350
    Thanks grape. when you say overdrive on alt, that's larger than stock? I have one that I took off. My situation got better when I went back to stock alt, and kept the under on the crank. longer belt makes sense. I a going to get the powermaster 140 alternator.

    Should I keep the stock pulley on there or put the overdrive pulley? Does it matter?

    Also, what battery? I have a NAPA premium- since I work for them. I can get the highest grade NAPA for nothing, but if I upgrade to Optum I would have to fork out some dough. Thoughts?

  7. #6
    Half Throttle
    Join Date
    Apr 2007
    Posts
    350
    Turbo what size is the stock alternator wiring and battery cables? 6 ga? I got a powermaster the other day and might upgrade. They call for 6 ga in the manual.

    Did you upgrade your wiring? If so, what did you get? I don't see any stock style harnesses that have the splits etc. I want it to look neat. I am running a side post battery.

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