Between Omaha and Des Moines, 7 miles South of I80 | Must be working on a Ford truck. (Do you have a push button, that you push to shutoff the truck ??????)
Looks to be a 3406A model.
The shutoff is a "electric over air" shutoff solenoid. All of that style, that I've been around, use electricity to allow air pressure, into that upper rod/plunger area, then that pulls a rod and shuts off the engine, BUT it must have enough air pressure to operate that rod/plunger assembly = that may be why it runs for a little bit, then shuts off = it is building up enough air pressure to be able to shut it off again. (plus, those get old and hoses get old, and they tend to leak off any air pressure, too.)
First, it would be nice to know, if you have any voltage, on that new little white wire, going to the "electric part" of that shutoff assembly. My guess, is it should only have voltage, while you are trying to shutoff the engine (like you hold in on a "push button" inside the cab, until it shuts off, then release pushbutton= it momentarily sends electricity to the shutoff assembly= to kill the engine)
If you don't have any electricity, down there on new little white wire, then I assume air is leaky pass the "electric part" of the shutoff, and getting into the upper "air rod/plunger area" , when this happens AND as the air builds up in the entire truck's air system, it finally gets enough air pressure to force the "upper rod/plunger assembly" to kill the engine.
Now, with a leaky air system and/or lines and hoses, air system drains off, and you are able to restart, but the whole cycle, then starts over as the truck gets restarted, it builds air pressure and once again, it kills the engine.
To by-pass, just remove air line(#4 aeroquip), and plug it = should get it running and stay running . (next, to shutoff = get visegrips, and clamp to that short shaft(sticking out about 1") and with vise grips, pointing straight up, when clamped on shaft; then you would push the visegrips towards the cab, to kill the engine.
Edited by 4WD 9/9/2013 23:31
 (3406A model shutoff.jpg)
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 3406A model shutoff.jpg (33KB - 576 downloads)
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CAT 3406 Won't Stay Running!
