wizman

have a 74 roadrunner fuel gage not working gage works if grounded removed tank and new sender sending unit smokes if set to full 3 volts coming back to sender when gage reads full voltage regulator grounded? ceramic connector shorted?

wizman

tested voltage across regulator 15 both sides ordered new one and a new sender don't want to burn out the new sender?

RacerHog

Should not have any voltage coming back to the sender !!!! Something is wired wrong for sure.....

wizman

thinking I will replace regulator and re-test with old sender new one ordered better idea? would a shorted gage go to hot at full mark?

RacerHog

1. If you unplug the wire at the sending unit, and the gauge goes to empty, thats good.
2. If you ground that same unplugged wire, the gauge should read full.
If those are happening, that tell you every thing from the wire at the sender all the way back to the gauge is in good working order.

If that is all good, your problem is with the sending unit itself.

wizman

I started out there, gage would not work when I acquired the car. they installed a comp harness and am still working out the bugs. gage works when grounded but sends 3 volts back through wire when it reaches full?? volt reg is not reducing voltage and will replace it today and retest by grounding wire at tank end. doesn't make sense to me unless gage grounds out at full or excess voltage is bridging gage

RacerHog

Ok... I see what your saying.... I think I'm with you now..
Your getting 12 volt to the resister... Your getting the 5 Volts out of the resister for all the gauges, Oil, Temp, Fuel, that are working ok? With the exception of the fuel gauge, reads wrong, because of the tank sending unit.

wizman

close, getting 15 volts on both sides of resistor/regulator none of the other gages are working, have been replaced by remote gages don't know why sending wire would go hot when gage goes to "full" sending unit was not working when I tested it sooo pulled tank and bench tested sender. when I hooked it back up remotely to car wiring to test the sender started SMOKING when the gage reached full mark. tested voltage. will bench test again after resistor replaced. thought I need another hot rod before I died but having reservations now.

wizman

car also has drive shaft vibration at moderate revs. CALTRAC traction bars are installed but drive shaft has no deflection angle. should be easy to adjust links and rotate diff . how much angle on shaft should I adjust to, shaft is dead level now.

RacerHog

What gauge has been installed in place of the oem ?

RacerHog

3-4* pinion side down.
Also Use the long shocks.....
CalTrac's work great once you get them working in your favor. Just my 2 cents.

wizman

thanks Bob, I have an under dash set oil, temp, pressure gages car is not stock but the rest of interior is original (restored) might hook up original gages as back-up. car was originally 400ci, now has 440wedge block, bored and stroked to 496ci, crane cam 531 lift with 191 overlap, 13to 1 pistons, edelbrock top end. dynos at 536hp with 727 trans goes good but reworking throttle cable and pedal, trans kick down converting to cable. I am 69 now so last hot rod. also have 66 bird and 80 vette to work on mostly done. will re-set trac bars while I have it on the rack. thanks again

RacerHog

Sounds like lots of fun stuff, Good that you stay bizy, keeps you young !! lol
AS for the fuel gauge. Try to get the number off the gauge? might not be for a Mopar, That could be whats giving you trouble, Just the wrong type gauge?

http://www.autometer.com/media/manual/2650-1079.pdf
Here is the link to the Autometer, Scroll down to the fuel gauge... That will give you the ohms your looking for....

Have a great day.... Be Blessed....