I decided that the best way to test was a fuel pressure gauge, which had been on order since Christmas. I'll say this for JEGS: they might be Chevy/GM/Mopar centric, but they got that 60 psi VDO pressure gauge to me pronto. So I hooked it up and, with 40 lbs of pressure in the fuel ring, tried starter.
Nothing. And the 3/4 injector bank was disconnected so I should have soaked the left side of the engine with fuel. Conclusion: either the injectors are gummed solid, or they are not having a signal sent from the ECU to trigger them. I pulled off the connector on the #4 (left rear) and hooked up my test lamp.
Sidebar: Why a test lamp? Why not a meter? Wouldn't a meter be more accurate? Sure it would, if the voltage signal stayed around long enough for the slow LCD display to register the change in voltage. But I didn't care presently about whether the amount of voltage was correct, but merely that it was THERE. A lamp is much preferred for this, as it can light and be seen by the naked eye much faster than an LCD display or even a meter can register. An LED is best, as it is almost instant on: no warm up time for the filament; but watch your polarity or you'll cook it. Unless you're trying to see injector pulses when the vehicle is idling, stick to a dumb incandescent bulb; its fast enough.
With the test lamp in place, I cranked the engine over and got nothing from the test lamp. I reviewed my service manual (Bentley) and discovered that ALL of the injectors must be disconnected, or the resistor pack will soak up your charge (which isn't much anyway) and won't even light the lamp. I disconnected the rest, praising and cursing the injector designer by turns; they are very robust, yet don't want to come off very easily when they need to release. With all four off...cranking caused the lamp to light rhythmically.
So here's what we know:
- The fuel regulator and pump pressurize the fuel ring to 40psi, which is correct.
- All of the injectors are in good conditionally electrically. No ground faults through the body.
- Despite power at the connectors and good fuel pressure, the injectors will not spray fuel.
Therefore: The injectors, all of them, are clogged.
Having come to this conclusion, I wanted to trace down one more peculiarity: why didn't the cold start injector open. There was pressure, there was power, and the cold start injectors is even lower tech than the standard injectors: it is pretty much just a spigot which pees fuel into the intake plenum for a set period of time when cold. Why didn't the cold start injector provide some fuel?
After reviewing all of the particulars, I discovered that the red/white wire on the starter (which, when energized, powers the cold start injector) has been removed...by me. Hey, who knew? There are TWO red/white wires, same gauge, both leaving this junction. Disconnecting the other one would have merely disabled the cab fan motor.
So with that hookup restored, and all of the other components back in place, I switched the key on, closed the starter switch.
The engine turned over and coughed several times, trying to start!
Hot dog! There's life in the old guy yet. Having made the commitment about a $300 stopping point to test the engine's ability to run, I promptly used up 1/3 of those monies and bought 4 new GP Sorensen injectors and 4 new copper resistor plugs. I'll replace the Bosch injectors and plugs, and we'll try this dance again. I wonder if I'll get away with re-lighting the engine with only an oil change, tuneup and injectors? Wouldn't that be sweet!
Since I had run out of things I could do on the engine (for lack of replacement parts) I used the time productively to go peek under the vehicle: This bus has the BA6 gas fired heater between the front and rear crossbeams, bang-slap in the middle of the vehicle. This whole boxed in area is covered with a corrugated steel plate that protects the heater's body from flying debris that might compromise it. That steel plate had to come off, both so that I could evaluate the state of the heater, but also just to evaluate the state of the body! The plate is put on before the factory undercoating is sprayed on, so all of the metal in this cavity is unprotected other than by a thin skiff of primer. THIS would tell me what condition the vehicle was in.
There a some ten or so bolts that have to come off, and with the aid of PB Blaster and a 4 foot cheater pipe placed over a ratchet and 13mm socket, I coaxed 9 of 10 bolts to come out after having been corroded in place for thirty five years. But that last character wouldn't yeild. It turned, but the bolt neither backed out, nor did the head twist off; it just spun in place. So I took it off with an air powered side cutter.
CLANK! And the cover plate was off for the first time ever. Well, it wasn't that bad. Surface rust but quite tolerable. And most importantly, there was no penetrating rust anywhere. So now I have a better view of where that Fellows Speed Shop style radiator is going to have to go. And I have no idea how I'm going to put it in a place that small....
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