After the tow … An exploration in a hot bus engine not starting.

So, in January, there was a nice, (relatively) warm day that I decided to take the bus out and fill up the bus’ fuel tank.  The drive down to the Rez was uneventful, the bus was driving nicely, and all was well.  I pulled up to the pump, shut down the bus, filled the tank, turned the key, and the engine spun.  It spun way too easily.  And it never caught.

Perplexed, I let it spin for twenty seconds or so, then stopped and waited a minute before trying it again, only to get the same result.  After about 10 minutes of waiting and trying to start, I’d run the batteries down.  Luckily, we have AAA (with RV), so I called for service, hoping I could get (at best) a jump-start, or barring that get towed to the dealership back in Buffalo.

After it started to rain and the tow driver (Justin or Jordan (Sorry!) from Bach’s Towing) arrived and sized up the situation, we found that we just couldn’t get sufficient juice from the tow truck to start the bus, so it got towed back to the International dealership (Regional International) where I get all my inspections and service done.   After them charging it and checking it, it started up right away, and continued to do so every day they checked.  One of the mechanics drove it around a bit, and it started after that too.  They just couldn’t replicate the problem.

The IDM, mounted on the firewall behind the engine, with the cover off.

They found an error message about a missed toggle in the IDM (Injector Driver Module), but it didn’t show up again.  And, as the IDM was an expensive unit, they didn’t want to replace it if they weren’t sure it was the problem.  This unit takes the 12 volt power and ups it to 115 volts(!) to control the operation of the fuel injectors.

So I went and picked up the bus from the dealership, and drove it to a local park (Chestnut Ridge Park, which was still fairly close to Buffalo in case things went really badly) so I could have some time to myself, and it didn’t start again. My hypothesis was that if the engine was fully up to temp (up around 180 degrees on the coolant), that was when the problem happened. So, I decided to wait half-an-hour and THEN try to start it.  After the wait, it started up fine.

The Eternal Flame at Chestnut Ridge Park

I drove it around inside the park a little to the head of a hiking trail, getting the engine back up to temperature (~180 degrees) and after shutting it down, it again wouldn’t start, it just spun.  After a hour-long hike, though, it started up great.

As the dealership had not been able to replicate the problem, and I had replicated it twice in the space of an afternoon, I was a bit annoyed.  So, I took to the internet.

It seems that there are three major issues with the T444E that can cause the ‘spin but not fire’ starting issues.  The first is the IDM, which, when it fails to send power to the injectors at the behest of the ECM (Electronic Control Module), the engine gets no fuel.  The second is the IPR (Injector Pressure Regulator) which is a solenoid valve to control the high pressure oil feed.  The third is the CMP (or CAMP) (Camshaft Position Sensor)  which notes a certain slot pattern on a camshaft disk which indicates that cylinder 1 is in the correct timing position.

Any one of these failing can get the ‘spin but not fire’ situation.  I could also get that if the fuel filter was clogged, but then it wouldn’t start when the engine was cold either. So, at any rate, the parts were ordered from Shop Injectors and updates are to come.

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