1986 c7000 box truck 366 engine won't start

[primemover]

All helpful thoughts, Rich. Would this pump need to be rimed, after having sat a while with an empty tank. I'll be back into this effort with the rising sun:)

[bd]

The GM pumps are self-priming.  But, if the pump check valves are gummed up or corroded, or if the diaphragm is perforated, replace the pump.

[bd]

...if the diaphragm is perforated, replace the pump.

This previous post was incomplete.  If engine oil dropped onto your clean fingertip quickly tracks outward along the finger ridges, the oil is contaminated with fuel.  Fuel dilution generally occurs when the fuel pump diaphragm perforates.  So, if there is fuel in the oil... replace the mechanical fuel pump.

[primemover]

So, I'm down to the part of this saga where the fuel pump has been identified as not pumping fuel. I have it out and I'm having fun scraping the mounting surface of old gasket material. long, but I'm getting it. I took a break to assess installation of the new pump, and I'm looking at the area around the mating surface I'm trying to clean. underneath that surface, on the exterior of this 366 engine, there is a bolt screwed into the engine. Is it of no consequence in this saga, or is it an access point for the pump's push rod, such that I could remove the bolt, push up the push road, and insert the new fuel pump?

[bd]

Remove the B+ primary lead from the distributor and have an assistant tap the engine over with the starter until the fuel pump pushrod is fully retracted into the block.  Be careful not to trap your finger with the pushrod while cranking.  The bolt hole on the front of the block maybe drilled through into the pushrod bore.  If so, you can use a nylon (preferred) or soft metal bolt to lightly retain the pushrod in the up position.  Be careful not to score the pushrod so that it binds in its bore.  Stabbing the replacement pump can be a little tricky, since the spring under the fuel pump arm will compress as the pump is slipped into place.  Pay close attention that the fuel pump arm doesn't slip off to the side of the pushrod as the pump bolts are installed and tightened.  Don't forget to remove the pushrod retaining bolt from the front of the block when you are done and reinstall the short bolt that you initially removed.  Then reconnect the distributor B+ lead.

[primemover]

Engine is running with fuel from the tank! 5 gallons in the 75-gallon tank was enough to get it going, but I'll add more now:)

Quite a saga. To start the diagnosis, I removed all the pump connections, then hooked up 6 feet of clear hose to a five-gallon gas can outside the wheel. Pump produced no fuel. Double-checked everything, tried again to no avail. Pulled the pump for positive ID of a replacement. Of course, I pulled the pump without looking for instructions, as all of my mechanical pump pulling was back many decades on cars that had push rods up from the top of the crankshaft, so they didn't get lost in the engine:( I could not access the bolt on the front of the engine to put in a nylon bolt to hold the push rod up. I did find an access bolt on the bottom of the push rod. After nudging the crank around to let the push rod up, I was able to get a dowel of a size to go into that hole and brace against the bottom of the push rod to hold it high enough to let the fuel pump arm in under the push rod where it displaced the dowel and allowed the pump to seat against the engine block while I screwed in the retaining bolts. (On my back in the driveway with a droplight, a collection of tools of destruction off to one side on a board to keep them out of the gravel, next 24 hours spent with a pretty sore shoulder -- but ok after that.) I let the Permatex 2 on the gasket cure overnight, as I surely do not want to do this job again!

Next, I moved to the carb, removed the old hose and took out the carb connection to find a filter -- none there. I decided on an inline filter just before the carb which was easy to cut into the new fuel line between the tubing from the pump to the top of the engine and the carb. Keeping some of the old lines, I wanted to be able to catch any line crud there might be before the carb.

Hooking up the pressure line to the carb (with Anti-Seize to ease the re-mating of the old pressure conn) and the return line, I put the clear plastic supply line from the gas can back on and cranked. Nothing but _leakage_ at the pressure side conn on the pump:(

Finding Permatex Aviation (#3) locally [not an easy search!], I cleaned off the remaining Anti-Seize and wire brushed out rust remnants, carefully put Aviation (#3) on the threads only, and eased it all back together. Turning the key in the ignition, I was rewarded with a running engine. I let it warm up out of the gas can before turning it off. Finally, I reattached the old hose from new inline filter back on the frame and the tank. Turning the key in the ignition gave me the satisfaction of a running engine without the life support of the gas can:)

Thanks to everyone, especially Rich for holding my hand through this adventure. now I'm into the braking system to see if I can replace enough lines to get at least front brakes working. The line to the rear has been out for years, and I'm just moving it around the yard or maybe selling to a farmer for mobile goat housing in the field, also flat terrain.

Gene