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Old 06-13-2017, 10:41 PM
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Walker Walker is offline
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Join Date: Aug 2004
Location: Cave Creek AZ
Posts: 3,984
Default Trailblazer auto idle repair

My TB251 has had trouble idling for a year or two. I diagnosed it with the tech manual to the board, but didn't want to pay for a new board. When the command came for idle it would send 12vdc up to the mag solenoid and pull it in, but itjust wouldn't pull hard enough, and it would also slip in and out.

I originally pulled the solenoid apart, cleaned and lubed the linkage, cleaned the wire connections, etc, to no avail. The board would put out 12vdc, just not enough amps.

Today I ran a wire down one of the conduits and attached it to the + post on the starter, same post that powers everything else. Then I connected that, the original solenoid power and ground, and the solenoid to an automotive 12vdc relay. Covered the wires with some nylon split loom, and zip tied the loom to the original moles connector holder. Powered it up and it works great! I have idle again.

When I had it running I noticed fuel leaking from the hose from the fuel pump to the carb. This is at least the second repair on this hose. It goes from the 1/4" barb at the pump to the 5/16" barb on the carb. They both point backward and the 3" long hose makes a U. I had to use a small piece of fuel hose stolen from my compressor (fortunately it had some slack).

I need to come up with a better way. Perhaps a U piece of steel tube with a piece of hose at each end. Likely it will just be a better piece of hose. At least I discovered this one before it completely ruptured, which would most likely occur on my job tomorrow when I need it. It was giving me some warning though, as fuel would drain back down into the tank, causing longer cranking times.
Chief slag chipper and floor sweeper, Ironwood Artistic
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