OK gurus, help me explain this!

[pbknowles]

My truck has always been hard to keep running after a cold start, with much smoke and misfiring etc. I had pretty much decided it was just a cold blooded SOB and given up on driving it when temps fell below about 10 deg. f. Recently I got a particularly bad batch of fuel, which gelled in our -15 deg. f. temps. I decided to pull the tank and dump it out (also to address bad level sender). Now, my truck was originally a gasser, and is a Chevrolet. I found the "sock" filter in the tank badly clogged with brown goo and ice crystals. I just removed it since I have a 100 micron stainless steel pre-filter before the lift pump and the stock Nissan filter. Refilled with fresh fuel with anti-gel added. Now, since I didn't really expect it to start (cold run) any better, and since it was really cold, I just drove my other truck. But right in the midst of the cold snap I had to move it (snow removal). To my amazement, it started and ran really well, with none of the shenanigans it used to exhibit. I have started it and run it in as low a temps as 5 deg. f without plugging it in with no problems. The only scenario I can come up with is that the clogged sock was causing the fuel supply line to be under a vacuum at engine shutdown. The vacuum would then introduce air from any tiny leak point, which would then end up in the IP at re-start. At higher rpm's the lift pump must have been able to overcome the restricted sock, since I had no indications it was starvinf for fuel while driving. I am puzzled.

[philip]

Was there a question?

[moose60]

Perhaps you could try to replicate the issue by putting some plastic food wrap under your fuel cap. This would simulate the plugged sock filter.

Do Datsuns have such a sock filter?

[philip]

SNIP- Do Datsuns have such a sock filter?

The vehicle is a Chevy S10, repowered by an SD22.

I once asked Al if a diesel 720 fuel tank he had out on the floor was equipped with an inlet sock in the tank. Al said he did not think so.

[pbknowles]

The question is: Why did I post this in "Users Rigs"?

[asavage]

Phil, we appreciate the declarative as well as questions.

[philip]

The question is: Why did I post this in "Users Rigs"?

I moved the post because its not an engine repair question nor is the vehicle a 720 Datsun/Nissan. ERgo... User Rig.

Had you found a faulty "lift pump", that would have made the post an engine specific discussion.

There's daily housekeeping that goes on here ... and I do only a fraction of it. Afterall, it's a hobby and a labor of love.

[pbknowles]

Aha, you fooled me! Perhaps not said often enough, but I am sure I speak for all when I say that the work that goes into maintaining this forum is greatly appreciated. I shudder to think of the hours I would have wasted but for the information contained here.