My intermittent starting problem is now 'mittent'.
I've fought this for a couple of years now - usually thinking it was fuel. Now I know its definitely power.
After being parked 'x' amount of time, coach refuses to start. More than once, it has just stopped running. Usually under that example, it would start right back up.
This time its refusing to start at all. I hooked up VMSPC and I get no comms from the ECU - but I do get trans temp with ign on.
So next I will break out the wiring and go from there. Solar panels keep the batteries up. No problem with running generator, engine turns over fine. Fuel visible in prefilter and purge runs fine.
As far as I know with the ign on, VMSPC should show me engine and intake manifold temps if the ECU is communicating.
Attached is spreadsheet showing the pieces and parts that have to work correctly for our starter to engage.
It was a big help in diagnosing our starting issues. And gave us a few places where we could temporarily bypass switches and relays to guarantee a start.
An important place to look is metering the neutral start relay on the front panel as it requires a good 12-volt feed to Allison computer, good grounds, good ignition start position voltage to do its job.
Hey, Barry. Excellent documentation! Gracias.
jor
Dave, Cranks but does not start ? My 8.3 was doing that just prior to failure of lift pump. I know yours is set up different but I tend to think fuel also. If it sits is fuel draining back into tank ? Or siphoning back ?. There may be fuel visible in bowl at filters but there still can be air sucked into injection pump. Is bowl is not clear full. If you can get fuel pressures read by installing gauge. If on crank it takes a while to build pressure I would lean towards a fuel issue. Good luck.
Gary B
Correct - cranks but does not start. Difference is this is an electronic engine and I have no indication the electronics are energized. Only the trans comes up.