Runs smooth, then sputters, then smooth, then sputters

[DoubleDingo]

@82sbshortbed I know, but....

@Ricko1966 Thank you for the reply, much appreciated. That all makes sense.

Here is the but.....
Yesterday after studying the vacuum routing sticker, I came up with an idea. The idea came from the fact I have mostly ran older technology, meaning no smog bs on a sbc, just a single hose for the vacuum advance pulling manifold vacuum. I never had any issues running any of those vehicles in varying temperatures or elevations.

That got me to thinking, undo the connections for the spark tvs portion at the carb and vacuum can, and plug both ends leaving it all there, and run a single hose from the carb port to the vacuum can, thus eliminating the spark tvs, check valve and vacuum delay valve and retaining manifold vacuum to the vacuum advance canister.

The same with the efe tvs, undo those connections from the carb and air cleaner assembly tvs, plug them and leave them in place, and run a single hose from the carb to the air cleaner assembly tvs, thus eliminating the efe, but keeping the functionality of the air cleaner tvs.

I am considering doing the same with smog pump, trc vlv and tla. By leaving them in place, I can simply remove my two-three hoses and put them in the glove box, hook up the emissions hoses back in their respective spots, and pass emissions, then undo it again for two more years. With the smog pump I need to see if I can get a shorter belt so it's not spinning while disconnected. All of the charcoal canister stuff would stay connected as they are.

This morning I did my experiment, it's still running rougher than it did after I fixed the vacuum leaks on Saturday, but it did seem to run better cold than it used to. I will be plugging the vacuum connection for the heater to see if that may be causing the new stumble condition. The cruise control port is already plugged.

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[DoubleDingo]

Since I couldn't get to it Wednesday night, I tackled it last night. The timing was way off! All these years I've had the truck it has been set to 10 btdc, and it ran really good where it was set. BUT! I now suspect all of the check valves and delay valves, etc are not working properly. By unplugging the spark tvs system and efe system the truck ran better. BUT! There was still a vacuum leak. At lunch yesterday I put a plug on the port of the trc vlv, the one that is supposedly to vent to astmosphere, and the idle settled down. Granted it still wasn't running right. Enter last night's tuning session. Set the timing to 10 btdc with the vacuum can disconnected and the line plugged. Then realized that I left the hose for the air cleaner tvs unplugged. Plugged it, reset the timing, lowered the idle, adjusted the carb, reset the timing again, readjusted the carb and got it dialed in pretty good. EXCEPT! I kept hearing an inadvertent vacuum leak, every time I heard the pssss the engine would stumble. So I decided to plug the dvtr vlv port. VOILA! The engine runs way better now! Even cold. I think there is still some bad fuel in the tank, so the truck will get driven lots of hours this weekend.

A side note: Ever since I got the truck, when I'd set the timing I would disconnect the vacuum can and then set everything according to the air cleaner label. Stock heads or vortec, the timing never moved when the vacuum was hooked back up to the can. I figured that was normal for these trucks and all of the bs they have on them. Now that I have ran it the old school way the engine is much happier. With everything still there I can simply plug it back in for emissions testing and then switch it back to my current setup after the testing is completed.

 

[DoubleDingo]

Truck ran great going up the canyon, the twisty road was nothing. Plenty of power, throttle response was good, etc. And then, after getting off the freeway, we decided to go check out the lake since it has been reported to be full. It was a sad sight for the last couple of years, could only see where the creek channels were for the most part. The lake is FULL!! BUT! The truck, after running so good, began acting like it was running out of gas. And then all of a sudden it cleared up. So we continued on. The tank was basically full, topped it off before leaving town. Drove around the lake, looked in awe at the amount of water in the mighty Kern, and how full the lake is now. And then was roughly 300 feet from Mom and Pop's when the truck just died. On the plus side, running the truck had charged up the battery really good, as it turned over the engine nice and fast. Although it would fire it wouldn't run. Pop towed us to their yard with his '68 F250 and of course got to hear the bs of that. Apparently he was having a bad day, normally he may have had some advice or been willing to lend a hand, but he had nothing.

So, me guessing it was fuel starvation I disconnected the line to the carb and turned over the engine. It barely squirted one squirt with the pre-filter hooked up.

Had to ask for something lay on because I didn't want to roll around in cat poop, but after bypassing the canister pre-filter downstream of the switching valve, it fired right up with a bump of the key like it always does. Not wanting to gum up the in-carb filter, I didn't run it very long.

Sunday morning, luckily the auto parts stores up there are open on Sunday, and the Carquest had the in-carb filter and two canister filters. Replaced both and it ran much better. Could tell the in-carb filter was getting clogged as we drove there to get the filters.

This run smooth and then sputter thing had been a laundry list of various things going wrong all at the same time. Bad fuel, vacuum leaks, gummed-up fuel lines, etc.

I did switch over to the driver's side tank to see how much fuel is in it. About a 1/4 tank. My plan of attack will be to put cleaner in the tank while I drive around a few weeks to let it slosh and break things up. Then drop the tank, pour out what is in it, replace all the hoses for that tank, and install a canister filter specifically for that tank, and then I can run on the driver's side tank.

After that, because I will basically run the passenger side tank down to empty, making it easier to drop it, I will repeat the process, also adding a passenger side specific canister filter for that tank, and of course will blow compressed air through all the fuel and return lines during this process.

This should end with a nice clean fuel line system and then I can be done with all of this crap.

The truck is running much better, but I definitely have caused a lot of stuff to get stirred up in the fuel system over the last couple of months in an attempt to remedy this condition.