'94 engine code 33, 35, or 78 cause no start? [Archive] - Diesel Place : Chevrolet and GMC Diesel Truck Forums

: '94 engine code 33, 35, or 78 cause no start?


Eric Murray
08-30-2007, 02:27 PM
Hey all,
Looks like a great site with hugely useful archives. I couldn't find much on my particular question, though. This is a new-to-me '94 1500 with 160k miles. It ran fine when I first got it for about 400 miles, then died intermittently for a few days until finally it wouldn't start. I tried off and on for a few days and still no luck. I went out about day 5 and unhooked the batteries to start troubleshooting, then realized I didn't verify it wouldn't start. So I hooked the batteries back up and it fired up immediately. I didn't do anything to fix the problem. I drove it daily for about a week (3-4 starts a day) and it started with just a touch of the key every time. Last night I started it and it died and wouldn't re-start...here we go again.
During the first bout of intermittent dying, I checked the fuel T-valve (good) and read the codes. Before I dug any deeper, though, it "healed" itself. The truck had a new PMD (relocated on an SSdiesel heatsink) and new fuel filter when I bought it. The codes I got were 33, 35, and 78. Could any of these cause this behavior? When the truck starts, it runs flawlessly. Occasionally on the highway at steady state the SES light will come on, but it goes out if I change throttle position. From my limited understanding of how these engines work, I don't see anything that would cause a no-start, but not show up once the truck was running. Ideas?
Oh, the codes are for "EGR control pressure/high", "Injector pulse width/short", and "Turbo wastegate solenoid".
Thanks,
Eric

roblrobl
08-30-2007, 02:41 PM
35 would be the only one that would make it not start. Verify your PMD connections. Might have to check it out with a scanner to see the actual pulse width.

Eric Murray
08-30-2007, 05:04 PM
What sets this pulse width? That is, what would need to be fixed if that's the problem? Also, since this is highly intermittent, would a scope pick anything up if everything happened to be working that day?