1993 Subaru Loyale - Only runs well on jump starter

I have a 1993 Subaru DL wagon, it starts and runs great when it has the jump starter connected but as soon as the jumper is disconnected the car runs really rough and if you try to rev it up it starts to die and something in the engine bay makes a hissing sucking sound as the throttle is opened but as soon as the jumper is reconnected it runs like a dream, whats going on?

That sounds like a main system voltage problem. Before the first start of the day the battery should measure about 12.6 volts. Immediately after starting the engine, 13.5 to 15.5 volts. What does your shop measure?


Thanks for the reply George
I haven’t been able to take it to a shop because there are none nearby and it’s not registered at the moment. I probably should have mentioned this in the original question, the car had been sitting at my grandparent’s place for a few years and my dad reckons that the battery is so dead that it is creating resistance in the system. I just wanted to get a second opinion on that theory.


Free car.
Buy a battery.
How much gas is in tank? Old gas?

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Battery needs a full charge, then a test. Or just replace it.

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