jtriggy

Hi Folks,

When driving, my aftermarket MECHANICAL SunPro gauges (Temp/Volts/Oil Pressure) are very "jumpy". At some points the Temp jumps to 250+ but comes back down pretty quickly and stays steady when at idle. The volts jumps between 12-14V but comes back to normal and the Oil starts at 40 and then goes to 0 after the car warms up. The grounds are good and connections are tight and obviously all gauges are connected to different things so it seems strange they are all jumpy. The Temp/Oil are connected to where the originals would go (front of engine, etc.).

The car eventually stalls after getting hot/driven because of very low RPM and I have to keep the gas up to keep it running. This I think is a separate issue that I need to look into. Already ordered a vaccum gauge.

Ideas on jumpy gauges?

You should know the engine is completely rebulilt and all accessories new, .030 over, flat top forged pistons, mild cam, reworked crankshaft, rolling timing chain, heads rebuilt, Performer intake/carb, high volume Mellot oil pump, etc. The only thing old/original is the external regulator which I've already picked up a new one for.

Thanks,
James

MJAKS462

Jumpy gauges equals bad or loose grounds. recheck all of your grounds , make sure you burnish the paint at bolt locations and get to pure metal.

jtriggy

My understanding was that the mechanical copper wire for the Temp and the plastic tube for the oil pressure had no electrical requirements whatsoever and that the red/black wires to each was *only* for the small bulb to illuminate them. I could understand a bad ground for the voltage meter fluctuation.

Did I misunderstand this for Temp/Oil gauges?

MJAKS462

I used autometer electrical gauges and they also said no ground was needed because the sending units serve the purpose of ground , but my gauges were jumping all over the place and pegging so I grounded all gauges and the bulbs and now they are fine.

MJAKS462

OIL pressure drop may be a leak in the plastic tube . I believe volts should read almost 14v , not 12v when car is running
I would run grounds and see what happens.