1993 LX 2.3L fuel pump voltage is low
03-31-2017, 08:44 AM
#1
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Join Date: Jul 2005
Location: Georgia
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1993 LX 2.3L fuel pump voltage is low
I hate to start a new thread, but searching posts produced nothing.
The car has run fine and then suddenly it will not start. The fuel pump has about 100 hours maybe, so that doesn't seem likely. I replaced the PCM (passenger shock tower) a few days ago and still nothing. The pump does not power cycle.
I decided to check voltage at the connector to the tank. On set of wires is 5 VDC and the other is 7 VDC. My understanding is that the 5 volt side is the sending unit, leading me to believe the 7 volt side is the pump side. However, it's hard to run a 12 volt pump on 7 volts. I check the rear interior light (same wiring harness) and got 12v there, so it's limited to the pump wiring. I tried grounding to chassis, but still 7v, so it's not a ground issue.
I'm not overly good with electrical, so I'm stumped. From everything I've read, there is no fuse to replace (plus I'm still getting voltage) and no other component between the pump and the PCM. I know some models had a relay or some such under the driver's seat, but this car did not.
Anyone had this same problem?
The car has run fine and then suddenly it will not start. The fuel pump has about 100 hours maybe, so that doesn't seem likely. I replaced the PCM (passenger shock tower) a few days ago and still nothing. The pump does not power cycle.
I decided to check voltage at the connector to the tank. On set of wires is 5 VDC and the other is 7 VDC. My understanding is that the 5 volt side is the sending unit, leading me to believe the 7 volt side is the pump side. However, it's hard to run a 12 volt pump on 7 volts. I check the rear interior light (same wiring harness) and got 12v there, so it's limited to the pump wiring. I tried grounding to chassis, but still 7v, so it's not a ground issue.
I'm not overly good with electrical, so I'm stumped. From everything I've read, there is no fuse to replace (plus I'm still getting voltage) and no other component between the pump and the PCM. I know some models had a relay or some such under the driver's seat, but this car did not.
Anyone had this same problem?
04-24-2017, 07:28 PM
#2
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Join Date: Jul 2005
Location: Georgia
Posts: 2,387
Something of an update. I finally had time to do some more testing. Turns out, when I disconnect the inertia switch, I'm losing the 5 volt side, not the seven. Exactly the opposite of what I expected.
Yea, I don't know.
Yea, I don't know.
05-10-2017, 05:21 PM
#4
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Join Date: Jul 2005
Location: Georgia
Posts: 2,387
Update #3:
The computer and wiring are fine. The pump might be fine, except the ethanol in the fuel destroyed every piece of rubber in or on the tank, including the shrink wrap on the fuel pump wiring. Not sure if it was a factory job or a previous owner, but bare wires were exposed.
New pump is tested and functioning normally. Awaiting gas tank vent grommet to arrive to re-assemble and install everything.
The computer and wiring are fine. The pump might be fine, except the ethanol in the fuel destroyed every piece of rubber in or on the tank, including the shrink wrap on the fuel pump wiring. Not sure if it was a factory job or a previous owner, but bare wires were exposed.
New pump is tested and functioning normally. Awaiting gas tank vent grommet to arrive to re-assemble and install everything.
