Originally Posted by BigRoy1978
From what I read, it would like you have a timing problem.
Get the truck warmed up and running and set the timing BY EAR.
Rev the engine up some, maybe 3000 rpm and move the dist more and less advance. The engine should speed up and slow down some.
Set it to where the engine is running the fastest, then back just a little bit.
tighten everything up and drive the truck and see if it helps. If it does, you have a problem with your timing!
Several suggestions have been made as to what the real issue(s) are, and I am trying to go through them one by one. Timing may very well be an issue since it was set by ear a few months back, and not by using a timing light. When it was set by ear, it was running perfectly. Just a couple of weeks ago it decided to start having these weird hesitation problems.
Got to do some work on the truck today. Continuing with the list in post #25, I installed a new thermostat. The bolts for the thermostat housing looked like crap. And I just cleaned 'em back in June of last year. (see post #130 here
. Anywhoo, in went the Fail-Safe 195 degree thermostat. The bolts got cleaned up using carb cleaner and a wire brush. The flush was not finish today.
I then fired up the truck and found that the recently cleaned glass filter was leaking fuel. Once everything got fitted ans tightened down, I gave it another start and allowed the truck to warm up for a few minutes before going for a spin. The truck was still not wanting to run smoothly so I just let it run in Drive on its own at about 20 mph up and down a small street. I kept an eye on the temperature the entire time.
Now, this truck has two temperature gauges: one on the dash and the other below the dash, about right in the middle so both driver and passenger can see it. In the past, I have noticed that the temperature on the goes up a lot more slowly than the reading on the gauge below the dash. But they have always come to the same temperature. Not today. Today, the temperature reading on the gauge below the dash was much higher than the gauge on the dash. I have not taken the time to trace which gauge connects where, but I am guessing one is giving the coolant temperature and the other is giving the engine temperature. Sound about right?
After the first spin in the truck, I pulled over and revved the engine again, all the way up to 4,000 rpm at times. I noticed that the truck routinely hesitated for a split second at the 2,500 rpm mark. I took the truck for a second spin to see if the transmission would shift smoothly this time, but no luck.
I then brought out the timing light, but before I hooked it up, I decided to check the vacuum for the vacuum advance canister. I have no idea what I was looking for, but I have to say that there was no vacuum pull on the carburetor where I had originally hooked up the line from the distributor. I immediately hooked the line up to another opening which was previously capped off and there was suction there. I unfortunately can't remember what the vacuum reading was. The engine rpm immediately jumped up from 750 rpm to 1,000 rpm on the tach.
I took the truck for yet another spin, but there was no difference in the hesitation and shifting.
I the hooked up the timing light and, try as hard as I might, could not see the indentation on the balancer as the light was flashing. I figured that it the color was just too dark so I tried using some pink nail polish (yes, I borrowed it. Leave me alone. Whatever )
, but that didn't do any good. I even sprayed some gold spray paint over the mark but still nothing showed up under the light. So I tried to see if perhaps the video camera or even the boroscope might pick something up, but no luck. And it proved quite challenging to operate two devices at once right over the spinning fan.
Maybe I am just losing my sight. Or is the timing off by so much it doesn't even land on the tab marks? Or is the engine speed to fast for it to be visible, in which case I should retard the timing a bit?
Next on the list: replace the rubber hose ends on the vacuum line to the transmission modulator. Test the modulator.