I have a strange intermittent problem with the gas gauge in the instrument cluster of my 1994 940.
The gauge reads the gas level more or less correctly at the start of a run, but after a few miles the needle drops back to zero. So I depend on the trip meter of the odometer to know when to fill up with gas.

Can anyone suggest what might be causing this and how I might go about fixing it?

Thanks,


Rob

I'll vote that it's likely at the tank. The fuel level sending units used in the later 940s are a known problem area. A longer sending unit barrel was designed for the larger tanks and had a different float/contact setup than the 740s and early 940s. The float contacts are subject to wear, resulting in sticky gauge readings and intermittent signals just such as yours. There's an article on fuel gauge problems and fuel level sending unit repair in the 700/900 FAQ. It includes a diagnostic procedure that will help you isolate the problem. The DIY fix with used parts is a bit of a PITA, but then the part is expensive from Volvo. As I recall, FCP Groton sells the entire sending unit for a 1995 940 and I think the barrel out of that would be the same as in your 1994.
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Dave -940's, prev 740/240/140/120 You'd think I'd have learned by now

hello, It doesn't happen often, but the circuit board that the guage is connected to sometimes developes a crack in the slim copper circuit. Check all from start to end point with volt/ohm meter to find your problem, but first set your oven to 100 and place board inside for 10 minutes. You may also want to check all the solder bridge points to make sure there is no cracking at pins.