Spent the day trouble shooting the fuel pump issue as now the RH side is intermittent and the LH inop. None of the repair manuals had wiring diagrams for the dual tank set up. Some time on the web landed me this:
After some quality time with the Fluke meter, it was looking like the transfer switch was the culprit. Pulled it out and carefully dissected it.
And one ugly looking set of contacts - that will cause the issue.
Some contact cleaner, 800 emery cloth and it cleaned up nicely.
Reassembled and installed, tested and there is power in all the right places now. Truck fired right up, pumps and gauges work on both tanks, problem solved.
Next issue was a high idle. GM TBI is rather solid so before making any adjustments wanted to check for leaks or mechanical issues. Vacuum lines are fair but no leaks found. Throttle body did not seem like it was closing all the way - and found then Cruise Control servo linkage was out adjustment, and holding the throttle open a bit. Re-adjusted and idles right down.
With proper idle, 2 working pumps it was test drive time - so off to Noti for a trip across the log truck scales.
Weights
F - 3650
R - 5600
T - 9250
This is with no passengers, no mattress, 10g of water, missing water heater, empty interior, 3/4 fuel. Nothing exact, just an idea of weights. Axles are rated 4500/7500 so plenty of capacity.
It ran great but did throw a CEL light but the LH exhaust manifold is leaking, so maybe an unhappy O2 sensor.