1994 F350 5.8L 63K miles.

Started running rough one day. This was after/during a couple weeks of heavy rain. I knew my forward tank had a leak (so I never filled it past half way). I suspected bad gas, put in dry-gas. This did seem to help. A Friday night I moved the truck near the house to load the trash for Saturday morning's weekly trash run. Saturday morning came and the truck wouldn't start. Just crank and crank and crank. So began my troubleshooting odyssey.

It had spark, as tested with Autozone's little spark tester. It had 40 pounds of fuel pressure. The oil looked good, no water, so I didn't suspect a blown head gasket. I saw no reason to suspect the timing changing overnight. I then suspected the computer (PCM) was not triggering the injectors because the injectors had 12V to them, and the continuity of the grounding line between the PCM and injector was good. I ohmed a couple injectors and they read ~15 ohms, which is good. I then checked error codes and found one: 33. Various references online said it means "EGR valve opening not detected". My Ford manual on CD says it's "TPS signal noisy". The TPS (a potentiometer) had good resistance readings. Likewise, the EGR valve position sensor. I didn't see how the TPS or the EGR valve could cause a no-start condition, but I replaced the TPS anyway. No help. Then I replaced the PCM with a refurb unit that has all the software updates from the last 17 years. Same problem. Then I changed the EGR valve. Same problem. So at that point I decided maybe I oughtta take a close look at the fuel... purged some out the test port and what do you know?... Not enough gas in my water! I had the new gas tank in the garage already (just procrastinating that job), so I pulled out the old one. There's the problem: a couple dime-sized holes rusted through the top, letting rain in *****-nilly. This was right below the gap of the bed and cab.

So, looks like I won't be Jet-Hotting my headers since I blew my budgeted truck-money on these parts (~$400). But I don't regret having spent the dough and replaced the parts, because they were all original and old anyway and now I won't have to worry about them for the rest of the life of the truck.

Here's the lesson... when verifying fuel delivery, check the quality, not just the quantity (psi) of the fuel.