TriPac engine no-start

Has the inline fuel filter ever been changed?. Also could be a weak electric lift pump, just before apu starts there is a warning buzzer that goes off, listen closely and you will hear the electric pump for about a second before starter engages. Willing to bet the unit hasn't been serviced properly and inline fuel filter hasn't been changed?. As it can be a pain in the rear. It is located in behind the air filter. Unless it's been relocated by someone. I moved mine for easier access.

 

I had a similar problem with my first one, it was a grounding issue. I ran extra ground cables between the unit block and the TriPac chassis frame, and between the chassis frame and the truck frame and negative post on the batteries. The unit relies on the ground from where it bolts to the frame rails, and that area can get corrosion into it.

But the fuel screen on the back of the unit is also often neglected.

 

I also had a similar issue. The only that trips that breaker on that box, is when that circuit grounds. That is caused by the oil pressure sender indicating low oil pressure or the temp sender indicating high water temp. I was having trouble with my breaker tripping at random times. Thermo king replaced both of the senders and the problem was still there.

I got tired of them trying to diagnose an intermittent problem. So I disconnected the wire from both senders, and the problem continued. Next I ran a new wire from the breaker to the temp sender then to the oil sender. Problem solved.

Some where that wire had an intermittent ground. I could never find where it would ground out, so the new wire is still on the unit. System works as it should, engine is protected from low oil pressure and high water temp.

I'm upset that Thermo King just thru parts at it and never diagnosed it. Sometimes those $100 dollar an hour shops aren't worth a @#$%.

 

I had a similar issue but noticed it always acted up at higher altitudes.. turned out there is actually a fix for this..

 

It was at right around one year old that mine had the starting issue that was related to grounding, and no the corrosion that was the problem is not visible, it would be in the space between the unit and frame rails, which could only be seen if the unit would be completely unmounted.

 

have you ever had or operated any other apu besides a tri-pac? I prefer moine with its 6500 watt generator and alternator and serate heat and air unit .