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Zero voltage on gauge only with ignition on?

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Old 08-25-2010, 09:22 AM
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Zero voltage on gauge only with ignition on?

One of my manuals says that the fuel pump relay is located in the engine compartment with the other relays on the passenger side of the car. I've been pulling it when I park the car but I was reading the other day that the fuel pump relay is actually in the passenger side foot well. I decided to check it out when I got to work. Pulled the relay and jumped into the car and the fuel pump came on. Started the car and it started up right away. Apparently in the '83 its the bulb check relay ('83 FSM page 128 position #4) - I'm pretty sure my Hanes manual said it was the Fuel Pump #2 relay but I'll double check. I mention that just in case it had something to do with my "problem" which I doubt.

I'm always watching the gauges, etc when drive the car - my dad hammered that into my head when he taught me how to drive years ago (even though he does nothing mechanical on any of his vehicles). Everything was working fine before I parked. After I pulled the Bulb Check relay and started the car the voltage readings were weird on the car like reading 6 volts when the ignition was on and the oil presure was pegged as well. I turned the car off and the voltage came back to its normal resting voltage of around 12V and the oil presure stated full on. Turned the car back on and the voltage reads at zero. Car off back to resting voltage of around 12V. I poped the hood to make sure the battery wasn't being shorted but I didn't have anything to measure with so I grabed the cable to see if it was drawing massive current to drag the voltage down to 6 volts. Not warm at all and the car runs fine so I think its the gauge but why it would read zero volts when the ignition is on is a bit of a mystery to me. The crazy reading on the oil presure gauge had me going as well so I pulled the plug on the oil presure transducer and started the car and the presure went back to zero so I'm sure the gauge is working fine. The transducer is weaping oil and there was oil on the plug as well but the boot wasn't full of oil so it must have just started leaking. I didn't bother plugging it back in and checking as the plug was covered in oil and I want to clean it before I plug it back in so I get an acurate reading.

Any ideas on why the voltage would be zero with the car running and return to 12V when the ignition is off? I searched but didn't find anything.... I thought when I disconnected the faulty oil presure transducer that the problem may go away but it didn't. There was still oil on the plug though so that may be causing a problem.

Last edited by FricFrac; 08-25-2010 at 09:33 AM.
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Old 08-25-2010, 10:32 PM
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I cleaned out the connector with some degreaser and blasted it with compressed air. Hooked it all up after work and the voltage was reading OK as was the oil presure. I'll keep my eye on it. The transducer is still weeping. Hopefully it was just the connector full of oil that gave me the odd readings. Just have to track down a new transducer....
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