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No power to 92 240 wagon fuel pumps

2manyturbos said:
Before you go any further test whether you are getting power to the fuel pump. The pump itself may have quit. You will need to have someone cycle the key on and off while you have a test light on the yellow power lead going to the fuel pump.
The body harness goes back to the floor area under the back seat on the driver side and goes down the fuel pump right below that area. There is a connector there for the short section of the harness that goes down through the floor. There is a 6mm bolt there that the pump ground wire attaches to.
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next on list tomorrow. ive been away. back on this job now.
 
2manyturbos said:
Report your findings and we can go from there. The ECU grounds the relay turning on power to the pumps. The orange wire going to the relay is switched power. That is what supplies power to the electromagnets in the relay. The yellow-black wire is the ground for the main relay. The blue-green wire is the ground for the fuel pump relay. The ECU is what turns those grounds on and off. This is a 1990 240 LH 2.4 diagram. The only difference between this one and you 1992 is the fuse F is located on your fuse panel. It is fuse 6 if I remember correctly.

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2manyturbos said:
Report your findings and we can go from there. The ECU grounds the relay turning on power to the pumps. The orange wire going to the relay is switched power. That is what supplies power to the electromagnets in the relay. The yellow-black wire is the ground for the main relay. The blue-green wire is the ground for the fuel pump relay. The ECU is what turns those grounds on and off. This is a 1990 240 LH 2.4 diagram. The only difference between this one and you 1992 is the fuse F is located on your fuse panel. It is fuse 6 if I remember correctly.

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this is very helpful. sorry for delayed response. been away. back on this job now. thank you.
 
haroldburbank said:
this is very helpful. sorry for delayed response. been away. back on this job now. thank you.
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ps. the fuel relay is powered with key on (tested). you mentioned yellow-black wire as ground for main relay. what is main relay? if this has to do with the bulb out relay, that could be a problem area. the harness for that relay overheated and melted a bit months ago, the relay was replaced and works. im wondering if the melted harness impacts the fuel pumps somehow.
 
Does the relay click over then when you turn key on? You usually can feel it click over holding it in your hand. I've fixed the relays by taking them out of the plastic box and soldering up the backside of the board where the relay is soldered in, it cracks the solder does. Other then that, take test light down to fuel pump, see if it lights up when relay clicks, if so and pump don't pump then pump is bad... You use test light at pump, put test lead of test light on the positive to the pump wire connection, then ground test light to chassis of car. This tests the ground wires to pump if no test light up test no worky then ground could possibly be bad, but if light lights up, grounds are good pump is bad...
 
haroldburbank said:
tested today. relay is powered with key on.
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Yes, but it's a two section relay. The large red wire has power all the time. The large red/yellow should get power when you crank. The first section of the relay turns on with the key. But the fuel pump section only turns on when the ECU detects the rpm signal from cranking.
 
found a disconnected wire at the external fuel pump. there was a rusted connector between 2 thin black wires of apparently 2 different gauges. i re-connected them. no luck. pump still does not prime. im on my back in the driveway. the front is jacked so i can see the electrical harnesses from below. will jack the rear next and unbolt the fuel pump bracket to test for power and other problems. cannot see or test everything until i raise the back of the car. so far there is no evidence power is getting to the pump. to me this means there could be a bad ground, a break in the harness under the rear seat, or the pump failed. all to be checked tomorrow.
 
sbabbs said:
Does the relay click over then when you turn key on? You usually can feel it click over holding it in your hand. I've fixed the relays by taking them out of the plastic box and soldering up the backside of the board where the relay is soldered in, it cracks the solder does. Other then that, take test light down to fuel pump, see if it lights up when relay clicks, if so and pump don't pump then pump is bad... You use test light at pump, put test lead of test light on the positive to the pump wire connection, then ground test light to chassis of car. This tests the ground wires to pump if no test light up test no worky then ground could possibly be bad, but if light lights up, grounds are good pump is bad...
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there is power to the relay (test light) with key on but i feel and hear no click. the relay is only 2 weeks old and only been switched on a few times for testing.
 
dl242gt said:
Yes, but it's a two section relay. The large red wire has power all the time. The large red/yellow should get power when you crank. The first section of the relay turns on with the key. But the fuel pump section only turns on when the ECU detects the rpm signal from cranking.
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thanks. did not know. will test and report tomorrow.
 
haroldburbank said:
there is power to the relay (test light) with key on but i feel and hear no click. the relay is only 2 weeks old and only been switched on a few times for testing.
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re-tested the fuel pump relay female connector sockets for power. good power at large red wire female socket (12 V). minimal power at red-yellow wire female socket. i have a digital test light. tester red light comes on during the test (power) but no digital read out, which i think means less than 1 V. this must mean very low power from ECM to fuel relay. tested #4 fuse (fuel pump) in driver's door side panel with volt meter. far below 1 V found there. all nearby fuses show 12 V with key on. wondering if bad ignition switch contact is causing power loss to #4 fuse. also hear some kind of relay cycling on and off at firewall near steering column but cannot see this relay. ideas? i have a spare ignition switch. will plug it in and re -test system.
 
You won't get fuel until the computer thinks it's making spark. So start checking the ignition for switching at the coil terminal 1 when cranking. If not there you move to the ignition amp on the left inner fender for signal testing from the ECU and to the coil.
 
haroldburbank said:
there is power to the relay (test light) with key on but i feel and hear no click. the relay is only 2 weeks old and only been switched on a few times for testing.
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dl242gt said:
You won't get fuel until the computer thinks it's making spark. So start checking the ignition for switching at the coil terminal 1 when cranking. If not there you move to the ignition amp on the left inner fender for signal testing from the ECU and to the coil.
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thanks. i dont know what an ignition amp is or location. pics? what about lack of prime of the fuel pumps (due to no power there)? even if the amp has failed the pumps should prime if all else normal right? i think i found the ignition amp next to the headlight high beam relay mounted on driver side fender wall.
 
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dl242gt said:
The ignition amp is the module bolted to the left inner fender right next to the battery.
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thanks. think i found it next to the high beam relay. even if the amp has failed, the fuel pumps should prime if all else normal right? so far cannot get pumps to prime.
 
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