tarus fuel pump


Old 05-06-05, 10:52 AM
Thread Starter
Join Date: Sep 2004
Posts: 238
tarus fuel pump

The car is a '94 3.0l taurus w/ 155k

Occasionally, the car will not start. This happens maybe 1 in 50 starts or about once every two weeks. After the second failed start, I put the key in run not start and listen for the fuel pump. I do not hear the usually thee-second hum.

The car will run if I wait a minute and try again or if I whack the relay w/ 24 wires going into it that sits above the radiator under a plastic shield. This relay is called a constant control relay module or an integrated relay depending on whom you talk to. Pep Boys sells them for $85 and the dealer sells them for $150.

While tracing another problem, I found that the car is setting codes 556 and occasionally codes 556 and 543 when this no start condition occurs. These are KOEO memory codes only, and the dash CEL never comes on. The car never dies once started.

The codes are 556 f. pump primary circuit failure and 543 f. pump secondary circuit failure.

I replaced the pump a year ago with similar symptoms because the pump had gotten very loud. The problem went away for about ten months. The symptoms have reappeared and in the interim, I did enough research to find the relay in question and pull the codes.

Is it the relay? The wiring looks good. The pump is cheaper to buy but a lot more work to change. Since it is a random problem how do I know when it is fixed?

I am hesitant to buy parts because in the fall I was sold every component of the EGR system (valve, sensor and vacuum control valve) by the dealer and others. The dealer even offered to order a computer for me for another $600 and someone else tried to sell me a maf sensor for another $200. I later fixed the problem myself by cleaning out the egr passage in the upper intake. I spent about $300 chasing down the problem that took me about 3 hours and a $5 gasket to fix.
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Old 05-06-05, 01:01 PM
Join Date: Dec 2001
Posts: 2,538
if tapping the integrated relay box gets the vehicle to start then I would suspect that to be the problem.
you could take the vehicle to a shop but they would need to see the vehicle acting up long enough to determine for sure.

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