Help!

[83Silverado]

Sorry, not a very descriptive subject line. But it's hard to describe in just a few words:

'83 6.2L n/a - A while back I was headed up a mild climb on the highway and the engine stopped dead. Not miss-miss-stumble-cough-die but from-2/3-accel-sounds-real-good-to-*silence* and coast to a stop. I assumed that it was airlocked and started going through the trouble-shooting procedure to bleed the injectors until I had a good weep from each one. I tightened everything back down and went to start it, but try as I might it wouldn't start. I checked the glowplugs, found two that weren't getting hot, and replaced the whole lot. After running the batteries down by cranking, charging them back up I tried it again, only to find that the starter wouldn't. I've dropped the starter and taken it to a local rebuilder, should be getting it back tomorrow. If the glow plugs are getting hot, and the injectors are getting fuel, what else could be going on? I've considered that the injector pump might be on it's way out, but it's only 3 years old. Hate to think that it's failed so quickly.

[catmandoo]

sounds like you lost power to the pump to just die like that check the wire for power could be fusible link related beings you have the starter off check them or the solinoid in the pump died.turn on the key and pull the wire off and on the pump and listen for a clicking

[britannic]

With a sudden stop on all 8, it does suggest a common cause like electrics, sudden air leak or mechanical failure at the IP or lift pump.

Make sure that the pink wire to the IP shutoff solenoid is getting full battery (battery fully charged) voltage. Check the operation of the shutoff solenoid on the IP, they can become weak and allow the shutoff rack to sping to the engine off position or close enough to it that there's not enough fuel to run the engine. It's unknown for the transfer pump in the IP to fail suddenly, but this pump is also affected by lift pump pressure.

Check the lift pump and also check the fuel filter and change if necessary. Restrictions or air leaks in the fuel return circuit can allow the pump to inject fuel but alter the timing enough that it isn't getting there at the right moment.

With an injector line nut loosened one turn, there should be a puff/spray of fuel upon injection, if not, tighten it a little to where you can see that puff/spray, if it only ever dribbles, then the IP isn't able to make injector pop pressure any more.

To check for air leaks, get a spare fuel tank cap and fit it with a tire valve, then pressurize the tank to around 7-10psi and inspect the fuel supply system for leaks.

[83Silverado]

Thanks for the advice. I don't fully understand the operation of the 'magic pink wire' and the solenoid, I'll have to dig into it a little more. That's a good trick with pressurizing the tank, I'll be sure to try that as well. The lift pump is new, so are the fuel filters, so I don't believe that's going to be it (but I'll try anything once). My poor Blazer has spent more days parked than running this year, and I really need to get it going before winter. I have yet to see a mist/puff of fuel, either with the injectors loosened or with the glow plugs removed. So it's looking like a fuel delivery problem of some sort. I just hope it's on the lower end of the $$$ scale.

Anyone know a good diesel mechanic in NE Tennessee?

[britannic]

The pink wire energizes a solenoid which pushes the shutoff rack from the no fuel position to normal operation under control of the throttle.

Do rule out the new lift pump as the cause of the trouble. If the injector line nuts are too loose, they won't puff/spray or mist, only drip, try doing them up finger tight and then see what happens.

[arveetek]

While I doubt this is your problem, I had the exact same thing happen to me on my '86 K-10 with a 6.2L n/a.

My problem turned out to be a sheared camshaft key, the one that holds the camshaft sprocket in place on the camshaft. My engine had been rebuilt by somebody else before I bought it, and they left a few bolts loose. When I tore it apart, I found the camshaft bolt very loose. This allowed the sprocket to wobble, shearing the key right off. The sprocket then just sat there, not moving at all. This in turn didn't move the injection pump gears, causing the engine to shut down, with a no fuel situation.

An easy way to check for a gear/sprocket problem is by removing the oil fill tube on the front of the engine. It's held on with two nuts. Then pry the tube out of the rubber grommet. You can then see the injection pump gear. Have a helper crank the engine over while you watch that gear. You should be able to see the gear turn over with the engine, at half the speed of the crankshaft. If it's not moving, then you know where to begin looking for the problem.

Again, this is a longshot, but it's worth checking for before condemning the injection pump.

The first thing to do is to make sure you have power to the pink wire going to the injection pump, as was mentioned.

Casey