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Re: bad ecu?-jumping pump relay to run Posted by RS [Email] (#15) [Profile/Gallery] (more from RS) on Sun, 4 May 2003 19:23:58 In Reply to: bad ecu?-jumping pump relay to run, corey jorgensen, Sun, 4 May 2003 18:55:30 Members do not see ads below this line. - Help Keep This Site Online - Signup |
One common failure mode of ECUs is that the transistor which the unit uses to activate the fuel pump relay becomes degraded by backfeed from the relay when it turns off. This is basically what happened to the ECU in my '89 900T.
So it sure sounds like the ECU. In a few instances, it could be the fuel pump relay.
If you have access to a good used one (or the time to get it mail order from one of the sponsors, assuming you're in the US), try putting in a new fuel pump relay and see what happens. The fuel pump operates off of one of the contacts in the relay. On mine, that contact was badly pitted, and added a bunch of resistance into the fuel pump circuit - the running for a while could possibly be due to a badly-pitted contact in the FP relay.
Depending on the year and model, ECUs from other years should work. For example, ECUs from '88 900S, early '89 9000, '90 900S, and '90 900T work in my '89 900.
In any event, as long as you get it running, buying a new FP relay won't be wasted money. You should replace the FP and system relays whenever you have an ECU failure to protect the new ECU.
Which year and model is the car? Which market (US, Euro, Canada) is it?
posted by 172.150.59...
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