Oil Pressure and Fuel Gauges inop 77 F250
#1
05-16-2013, 07:35 PM
Oil Pressure and Fuel Gauges inop 77 F250
I went to move my trusty `77 for the first time in a couple of months and had no oil pressure indicated. Had my son climb up with a voltmeter, he reported several volts at the sending unit which I interpreted to mean that all was well in the gauge circuit, so I suspected a broken oil pump drive shaft. We pulled the sender and no oil came out after ~10 sec or so of cranking, so I assumed the worst and dove in to replace the oil pump drive shaft. Fortunately I chose to try cheating and do it from above, because when I got the distributor out the shaft was fine. Made a tool to spin the pump with a drill and got plenty of oil out the sender hole, so now I'm thinking maybe the pump just lost its prime. Put the distributor and sender back in, fired right up, but still no oil pressure showing. No gas gauge reading either, but I hadn't thought anything of that initially 
I've got voltage at both ends of every fuse in the panel - does Ford actually run the gauges straight off the key with no fuse protection? Has anyone gone through this before, who could perhaps give me an idea where would be the next place to check? I guess I need to see if there's power at the blk/gy wire on the switch and if so yank the instrument cluster and start tracing; is there a specific component in there like the voltage stabilizer that's known to go bad?
I've got voltage at both ends of every fuse in the panel - does Ford actually run the gauges straight off the key with no fuse protection? Has anyone gone through this before, who could perhaps give me an idea where would be the next place to check? I guess I need to see if there's power at the blk/gy wire on the switch and if so yank the instrument cluster and start tracing; is there a specific component in there like the voltage stabilizer that's known to go bad?
Last edited by MarcV; 05-16-2013 at 07:38 PM.
#2
05-16-2013, 11:24 PM
Welcome to the site..
To check the gauge/circuit ground the sender wire and it should sweep and 'peg' the gauge quickly. If so, you can take the gauge/s out of the diagnostic. Good chance for a failing sender, but checking pressure with a installed mechanical gauge is always good insurance..
The gas gauge test would be the same, ground the sender wire and the gauge should peg. Was pretty common for the tank float to crack under/around the lever arm attachment, filling it with fuel and sinking the float for an empty reading
To check the gauge/circuit ground the sender wire and it should sweep and 'peg' the gauge quickly. If so, you can take the gauge/s out of the diagnostic. Good chance for a failing sender, but checking pressure with a installed mechanical gauge is always good insurance..
The gas gauge test would be the same, ground the sender wire and the gauge should peg. Was pretty common for the tank float to crack under/around the lever arm attachment, filling it with fuel and sinking the float for an empty reading
#3
05-17-2013, 12:07 AM
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you're troubleshooting your truck's fuel system to find out why the fuel gauge isn't working (or not working accurately) or simply need to know how to check a junkyard part, knowing what to do can save you a lot of headaches and money in the long run. On this page I hope to give you the information you need to know to make an accurate diagnosis of your parts. I'm only going to be covering factory setups on this page, however, since the vast array of aftermarket auxiliary fuel tank setups would obviously make this tutorial an impossible task.
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2013 MERCEDES BENZ SL-CLASS
-
you're troubleshooting your truck's fuel system to find out why the fuel gauge isn't working (or not working accurately) or simply need to know how to check a junkyard part, knowing what to do can save you a lot of headaches and money in the long run. On this page I hope to give you the information you need to know to make an accurate diagnosis of your parts. I'm only going to be covering factory setups on this page, however, since the vast array of aftermarket auxiliary fuel tank setups would obviously make this tutorial an impossible task.
----------------
2013 MERCEDES BENZ SL-CLASS
-
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