So, the results from this weekend...
As Most of you suspected, and counter to the premise of the original post, it was the fuel pump. Again. Third one.
While testing the fuel pump pressure (using a fuel/vacuum tester), we found the pump putting out between 2.5 and 3 lbs. But, it was also leaking gas onto the ledge of the block just above the oil pan. Went to pull it and a LOT of gas poured out of the pump from behind the pump (engine side) as we did so.
I replaced it with a pump I cleaned up that I pulled from a 261 in a junkyard a week or so ago (See ODSS Winter Junyard Tour). This was an ancient DA pump with glass bowl and gunk everywhere. But, when we installed it, it worked. Well, it has two weep holes that were leaking gas, but slow enough that it wasn't dangerous.
Truck started right up and we got good pressure from the DA.
Moved on to the compression test. SWEET and I worked at bit at understanding how the testing equipment worked, but that done, the compression test showed 120 to 130 lbs in all cylinders. Not bad...and it probably means the rings are good.
As a side note, and based on the question Red posed about the larger fuel valve orifice in the Carter carb, I backed the mixture screw down to zero and checked how many turns out it was set at. It was around two. I returned it to 1.5 for the subsequent tests. The truck started and ran (without producing soot) with no choke applied. Interesting.
After a couple of test runs, idles, and resting, we checked the oil for volume and smell. Had a hard time detecting fuel smell in the oil, but I think there was some (my pump was leaking into the crankcase while doing the compression tests and before replacement with the DA). I will check it again each day another week of running.
Thanks to everyone for their inputs. I will report back on oil volume and smell after a week or so of further testing, but I think we have found the culprit. I have a new SA glass bulb pump (because they look cool and I am hoping these specialist shops have pumps that are not already dry-rotted) on order from AmericanClassic.
Regards,
Jim
