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Crank, No start..Battery drains after a few cranks


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My Subaru impreza 1995 has a new fuel pump an fuel pump relay. When I position key to on I can hear the fuel pump priming an the relay click....As i keep cranking the battery starts draining within 15 seconds of cranking!.. its a fully charged battery but it is a old battery.. took it to the auto electrician an he thinks its the E.C.U....Please help I really need It to get to work...Any ideas will be appreciated

Edited by AlexAhiao
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They should be able to test the health of the battery, put it on a Load Tester.

 

I doubt it's the ECU.

Are you getting spark?

If you put a little fuel down the Intake and then try to start it does it start and run for a bit?

Does it turn over by hand and feel normal?

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You either have a seriously bad battery, assuming it is really fully charged. Seems to me that if the battery were fully charged and you could drain in in 15 seconds you'd see smoke or smell ozon.

You likely have a starter that is grounding internally, a really badly damages set of windings or brushes inside the starter.

Draining a fully charged battery in that short of time is distributing a lot of amps through wiring not build to handle it.

I have a 750 cca battery in my 97 lob. At 750 cca@12v discharge in 15 sec your looking at an an equivalent of 200v in heat. That'd fry your battery and anything close to it.

Cold start You should be looking for is about a 300 and up amperage draw on the intial surge followed by a roughly 125 amp steady reading. (engine being cranked over and disabled where it will not start as you said yours won't start.)

 

 

 

Use your voltmeter and ch can starter draw.

Edited by shoebee2
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^^^ that. I'd try and boost the battery. If the car starts, leave it running. If it dies out then it could be your alternator or something in your charging system. If it doesn't start, it could be your starter although if you have a manual transmission you can bypass the starter by putting the car in first gear with your foot firmly pressed on the clutch and get a few friends to push start you. Once you're rolling along then release your foot off the clutch and the car should start if it's a starter issue.  

 

You may have more than one issue going on here, but I do know one thing for sure, and it's that you definitely need a new battery. What battery do you have in this car? Any newer technology battery (VRLA/WETcell) we call a "two boost" battery (battery gets drained two or more times) before it usually won't hold a full charge due to it now being damaged and in your case, "old" as you say. And how do you know it's fully charged? If you've charged your battery with a battery charger, many chargers won't recognize a 12V battery if the voltage goes too low and it may only charge the battery to 6V or less or not at all, which isn't enough to start a car I think you need around 10V? What I do in those cases when there's a dead battery, is to set the battery charger to 6V battery setting and let the charger charge the battery to 6V. Then change the charger setting to charge a 12V battery and leave it on overnight or until it says it's fully charged.

 

The battery charger I like the best (and I've tried many) and that I have now is the NOCO G3500. With the Noco charger they have a desulfation/repair mode and I've used that one on my Red Top battery to bring it back to life after 3 discharges due to a faulty car security system.

Edited by coryl
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Great information from Coryl.  Recently on my 02, the car would not restart after I drove to a local store [the starter would just click].  When I jumped it, the car started and I could drive it home.  It turned out to be a bad alternator.  I believe that the alternator was just good enough to allow the car to be driven 10 miles, but not enough to charge the battery.  The car was dead in the driveway after getting home.

 

So the OP needs to change the battery and then maybe the alternator.  The alternator should be generating more then 13.5 v accross the battery terminals when idling. 

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