Onan Generator Question

[712edf]

At work we have a 92 Ford F350 with a 28' Telsta aerial platform unit powered by an Onan 4500kw generator. This is an ex-GTU Telephone company bucket truck that we use in our painting operations. The Onan unit uses the truck battery for starting electrical power, then is supposedly self sufficiant to power a hydraulic pump which sends power to the various hydraulic cylinders that do the actual lifting & articulation. There is also a couple of 110volt receptacles that the generator supplies. Inside the cab of the truck is a toggle switch which must be closed before the generator will operate. Turning off the toggle also kills the generator, same as 2 other kill switches which I suppose work similarly but they are push & hold type switches.

A few months ago the generator got where it would not crank/start/run during high humidity weather. Early morning dew, frost or a rain shower would render it inoperable. Once the weather dried up, things would be fine, except the 110v receptacles no longer work.

Now its dry as a bone out, but no worky for the generator. I have cleaned all points of contact and definately have power back to the unit via the main power wire off the battery. But I don't have any power to any of the "ignition" components. I came to this conclusion since I can jump power to the starter & get it to crank, but have no spark at the plugs. Cleaned plugs & shot ether to them, nothing.

Is anyone familar with these things? I can see several potential sources of electrical issues. In addtion to all the wiring on the generator engine itself, there are 2 control panels. One on the pedestial & the other at the bucket.

I learned years ago to never kill this thing while up in the basket. Once crawling down the boom is enough in my lifetime.

Thanks

Bucky

[Gordon Maney]

Do you have any spark at the coil wire? Is this a breaker point ignition, or electronic?

Is it a multiple cylinder engine?

[712edf]

2 cylinder similar to riding lawnmower engine. I had 3 paragraphs typed here but, my wireless disconnected itself when I hit submit. I'll just say that I'm not getting power at either start switch. I suspect a faulty kill switch or open circuit. I wish my first description had went through, too tired to retype it. Thanks

Bucky

[712edf]

I didn't fix it, but its working.

Well this afternoon ( after it was still dead) I removed the covers from both control panels, took an old stiff paint brush & knocked years of built-up dirt/dust from all the wiring/connections and made a point to jiggle every wire that I could get my hand on. I looked to see if there was any visible corrosion or wire breakage/damage. I should have blown everything out with compressed air.

I flip the underdash toggle switch ON then hit the start button on the boom. She fired right up!!!!!

I sprayed everything down with WD-40 before putting the covers back on the panels. I then used the boom to lift a 66 sweptline cab off of the frame & also to move a motor out of the way.

The big test is in the morning, when moisture will be present. I did wrap everything in plastic for the night to keep moisture out as much as possible.

Bucky

[Blisters]

You got it, I bet. dirt and moisture on anything remotely "electronic" will short the circuits sufficiently to do what you reported.