fuel pump relay ?
04-04-04, 04:23 PM
#1
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fuel pump relay ?
were is the fuel pump relay on a s4 n/a? its my buddies car and hes not getting voltage to the fuel pump..what could it be? i checked the fuses, everything looked fine... can this relay be tested?
thanx in advance for any info
thanx in advance for any info
04-04-04, 05:16 PM
#2
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The fuel pump circuit-opening relay is under the dash by the steering column. It's black with a yellow 5-pin plug. See the FSM for testing the fuel pump circuit.
Last edited by NZConvertible; 04-04-04 at 05:21 PM.
04-04-04, 05:20 PM
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The fuel pump only operates when the engine is running OR the key is HELD to START.
It does not run if the key is turned to ON and the engine is not running. Just some FYI
It does not run if the key is turned to ON and the engine is not running. Just some FYI
04-04-04, 05:24 PM
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Ya. I noticed while doing some testing that the pump only turns on while the engine is turning. Not really running. Im guesing its getting a signal from the CAS maybe?
Justin
Justin
04-04-04, 05:59 PM
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Nope. There are two ways the relay gets pulled in. One is from holding the key to START. That energizes the Circuit Opening Relay which in turn feeds the pump.
The second way of energizing the same relay...is when the air flow meter opens just a crack. When it does that a switch in the afm sends/makes a ground to the Circuit Opening Relay, which energizes the relay which then feeds the fuel pump.
A third way is something called a Fuel Pump Check Connector, located just aft of the afm. It's yellow in color. Has two sockets. When a piece of wire is inserted b/t the two sockets, and the key is to ON, the jumper makes the same ground that the afm usually makes to the Circuit Opening Relay, which in turn makes the pump work.
Bottom line is ....the switch in the afm is what keeps the pump a working once the engine is working. Just remove the filter and push the vane with your finger, with the key to ON, and you'll make the pump work.
The second way of energizing the same relay...is when the air flow meter opens just a crack. When it does that a switch in the afm sends/makes a ground to the Circuit Opening Relay, which energizes the relay which then feeds the fuel pump.
A third way is something called a Fuel Pump Check Connector, located just aft of the afm. It's yellow in color. Has two sockets. When a piece of wire is inserted b/t the two sockets, and the key is to ON, the jumper makes the same ground that the afm usually makes to the Circuit Opening Relay, which in turn makes the pump work.
Bottom line is ....the switch in the afm is what keeps the pump a working once the engine is working. Just remove the filter and push the vane with your finger, with the key to ON, and you'll make the pump work.
04-04-04, 08:41 PM
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[ A third way is something called a Fuel Pump Check Connector, located just aft of the afm. It's yellow in color. Has two sockets. When a piece of wire is inserted b/t the two sockets, and the key is to ON, the jumper makes the same ground that the afm usually makes to the Circuit Opening Relay, which in turn makes the pump work.
[/B]
[/B]
thats what i did and thanx for the relay info
04-04-04, 09:13 PM
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Don't leave it like that for long. The jumper wire bypasses the safety switch in the AFM that cuts power to the fuel pump if the engine stalls. This is to stop fuel being pumped out of broken fuel lines after an accident. The reasons for doing this should be obvious...
If jumpering the plug is the only way to make it work, it's probably a faulty safety switch in the AFM. It should be tested as per the FSM, and the AFM replaced if necessary.
If jumpering the plug is the only way to make it work, it's probably a faulty safety switch in the AFM. It should be tested as per the FSM, and the AFM replaced if necessary.
Last edited by NZConvertible; 04-04-04 at 09:20 PM.
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