Expert: Brad Sears - 12/8/2008

Question
Mr. Sears,

I've had older autos in the past and am comfortable with turning a wrench. I recently acquired a 1984 GMC Sierra 2500 with 38k on the clock. I'm the third owner and the second owner put 2k additional on it over five years. Most indications ("newness" of the gas/brake pedals, orig tires and lack of wear in other areas) suggest that the mileage is genuine. Still, the truck has a few "Issues" I am hoping you can help me ID the source(s) of. The truck has sat idle and unused for long-ish periods in its life and I suspect that the lack of use has contributed to some or all of the problems I'm seeing.

1. I was told the first owner got rid of the secondary gas tank on the passenger side of the vehicle. The gas gauge needle is pointed to the 3PM position in the housing about 20 degrees past the marker for Full which is at 1PM. The needle does move when gas is added but I have no idea where EMPTY is in relation. Is this a sending unit problem or has the needle rotated within the mechanism? Ideas?

2.There is what sounds like a belt whine/squeal...more of a high-pitched chirping that increases in frequency when the truck is under power from 10MPH upward. The chirp isn't present at idle. Power steering fluid is topped off, the belts appear to have the proper tension and are not cracked/crazed and don't show abnormal or excessive wear. Any ideas?  

Answer
The chirping noise is probably an exhaust manifold leak under power. A little kerosine down the carburetor intake when the engine is running will cause smoke and should pin point the problem. The second one will take some 007 James Bond work. I have no idea what the previous owner did when removing the second fuel tank. You will have to start chasing wires and fuel lines looking for the switching devices from tank one to tank two. And then chasing to see that he has the fuel gage connected correctly. Then with that done run the standard checks for fuel gage systems. That is to remove the wire from the fuel sender and ground the end that comes from the dash. Turn on the key and the gage should go to full. If it does not the gage or the wiring to it is bad. If the gage functions then the problem is in the fuel sender.
Brad