Fuel Sending Unit

[dmfconsult]

My sending unit is not matched with my VDO gauge (when tank is full, the gauge reads 1/2). The VDO sending unit is not a component that has the fuel draw outlet incoporated in the assembly so I have to find a FS_Unit that incorporates the fuel draw outlet and has the same resistance range as the VDO unit. Does anyone know what part I need?

Thanks,
Dave F.

[dscott]

The sending unit that comes with the fuel tank from Classic is the correct one. I'm not following what you have in yours. If you didn't use their tank or sender then use a GM 0 to 90 ohm from VDO. If you are using the Classic sender you may have a ground problem. I always run a separate ground from the dash to the cowl bar. If you don't you will get false readings from your guages. There is a single lug ground that goes to the speedo mount which is wire #190 run a ground from that point to the cowl. If I missed something in your explanation please let me know.
Don

[dmfconsult]

Don, since I did not assemble my Cobra I'm not sure of the source of the parts. I am assuming that the tank and sending unit is what CRL provides. The I.P. consist of the VDO "Cockpit" kit.
When I received the car I was told that included with it is the correct sending unit provided by VDO (which has to be installed if I wanted a correct gauge reading). I removed the tank and the FSU (fuel sending unit) assy. I found out that the VDO assy did not provide an outlet to draw fuel from like the one I removed, further, I found the the physical size of the VDO FSU would not fit into the tank opening. So I'm wondering what sending unit should go in there. Was the CRL FSU defective or is the resistance ragne incorrect. I have asked VDO for the specs. on their gauge but they do not respond. Is anybody else using VDO with the CRL FSU? The tanks 19 gal.

Dave

[Double Venom]

Dave
A couple of ways we fix this problem: Pull out the CR sending unit, gut it, but leave the pick up, re-install. Drill a proper size hole for the VDO or any other gauge sending unit and re-install it.

Problem solved.

Or: We simply take the VDO and the CR's sending units apart, swap the VDO unit for the CR's unit.

Clear as mud - huh?
DV

[dscott]

I have had 2 problems with the fuel sending unit and guage from Classic. I have had several sending units that the float was wrapped around the pickup when installed in the tank. The fix was to remove the sending unit and release the float. The problem from this was the guage always reads empty. The second problem was the guage itself. This is a recent problem so I don't know if the fuel guage was ordered incorrectly or just bad. The problem was the guage would only show 1/2 tank when full. This 2nd problem can also be the ground problem I discussed earlier.

I just checked the last guage that didn't work properly and found it is a 33 to 240 ohm. This explains the problem since the sending unit is 0 to 90 ohm. I will call Classic and let them know.
Don

PS. I just talked to Pete and they are checking thier fuel guages to make sure they are the correct ones. If you have this problem on a recently purchased guage from Classic you should call Pete for a replacement.

[dmfconsult]

Following is an address to the VDO FSU test procedure sheet, I have the 10-180 ohm FSU. I'm gonna have to ensure it is indeed the one compatable with the I.P. gauge. If so, what R my options?

Dave

http://www.vdona.com/Tech%20Support/...resistance.htm

[dscott]

The fuel gauge should be marked. There normally is a label attached to the back. If they are matched then one or the other is bad. You can pull the parts and do a bench check with a battery and some wire. The gauge requires power, ground and the wire from the sending unit, the sending unit requires a ground. Once power is applied to the gauge you can work the float up and down and watch the gauge for proper reading.
Don