Probably a dirty or broken fuel sendiing unit is causing your fuel gauge to read wrong - the FSU malfunctioning is a common problem. The sending uint can be removed through the med kit and the fuel tank is in the trunk behind a metal panel. Look up an old reply by me in the Diesel Forum about working on the FSU - lots of good info!

Good Luck!
Tom

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America: Land of the Free!

1977 300D: 300,000+ miles

American Honda: Factory Trained Technician & Honor Grad.
Formerly:
Shop Foreman;
Technical Advisor to Am. Honda;
Supervisor of Maintenance largest tree care co. in US for offices in Tex.