Gas Gauge not reading
04-09-2009, 10:05 AM
#1
Instructor
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Gas Gauge not reading
I bought my 1984 corvette from a private owner. When I bought it, he told me that when he replaced the fuel pump, he forgot to hook up the fuel gauge. The gas gauge always reads 100% full. I haven't taken the pump out yet, so my main concern was...
Do you think he broke the fuel level float assembly when removing/installing the new fuel pump? Or does his story fly?
What do you guys think?
Thanks!
Do you think he broke the fuel level float assembly when removing/installing the new fuel pump? Or does his story fly?
What do you guys think?
Thanks!
04-09-2009, 10:21 AM
#2
Team Owner
Have you confirmed that the gauge wont go down? The '84-'89 gauges are not exactly the most accurate especially the gas gauge, mine works when it wants to but it does work.
04-09-2009, 12:29 PM
#4
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St. Jude Donor '10-'11
Mine is accurate down to the drop. Ask me how I know.
I had that problem. Most say it's the sending unit. I bought a new sending unit and had to sell it because it did not fix my problem.. The gas gauge was frozen due to a broken solder. Fixed the solder and it is as accurate as ever. When it says you have 0 gallons left on my car, you have 0 gallons left.
I had that problem. Most say it's the sending unit. I bought a new sending unit and had to sell it because it did not fix my problem.. The gas gauge was frozen due to a broken solder. Fixed the solder and it is as accurate as ever. When it says you have 0 gallons left on my car, you have 0 gallons left.
04-09-2009, 12:40 PM
#5
Le Mans Master
If the float /pump assembly is anything like the later C4 models that I am familiar with the pump and float wiring are all on the same plug and not separate. The only way to find out what’s going on is to remove the float unit and check it out.
Find the wire that is for the float unit (wiper) and the other one is just ground. Measure the resistance and see what it is. If your float is anything like mine the resistance is approximately 10 to 110 ohms as the wiper moves across the wire coil. You have to find out if electrical contact is made, if the wiper (coil) is dirty, if something is broken or what’s ever wrong. If for some reason it all checks good, then there is a problem with the fuel gauge/car electronics.
You can actually do a preliminary check with out removing the unit. There are only 3 wires probably, fuel gauge, pump and ground. If you disconnect the plug under the fuel door assembly you can measure this. Having a FSM and having the color code would give you all the necessary information. However depending on your knowledge, if you find ground, then you can check the other 2 wires. The pump will definitely have low resistance and the other is the float. If you can’t read any resistance, its open and needs further investigation. The resistance will depend on your gas level.
If you do pull the unit to check it out be sure the sock on the pump was not left off.
Find the wire that is for the float unit (wiper) and the other one is just ground. Measure the resistance and see what it is. If your float is anything like mine the resistance is approximately 10 to 110 ohms as the wiper moves across the wire coil. You have to find out if electrical contact is made, if the wiper (coil) is dirty, if something is broken or what’s ever wrong. If for some reason it all checks good, then there is a problem with the fuel gauge/car electronics.
You can actually do a preliminary check with out removing the unit. There are only 3 wires probably, fuel gauge, pump and ground. If you disconnect the plug under the fuel door assembly you can measure this. Having a FSM and having the color code would give you all the necessary information. However depending on your knowledge, if you find ground, then you can check the other 2 wires. The pump will definitely have low resistance and the other is the float. If you can’t read any resistance, its open and needs further investigation. The resistance will depend on your gas level.
If you do pull the unit to check it out be sure the sock on the pump was not left off.
