So recently I have been having a weird hesitation at around 65mph in 5th gear. It doesn't happen in any other gear or rpm so I think its a load thing rather than an engine speed thing. Its not consistent either, I'll cruise for a few minutes fine and it'll hesitate a couple times and either goes back to normal or I take it out of gear and put it back in and will be fine for a little bit.

I thought it could be bad gas because my tank was almost empty at the time but it is still going on with fresh gas from a different station. Tomorrow I am going to pull the spark plugs and check them out, check the cap, rotor and coil as well. I was wondering what else you all think I should check out?

 

Welcome j3h. Is your dash light coming on? I had hesitation at speed also. Read the code thrown and it was the coolant temp sensor. Plug wires? just a thought.....

 

Thanks no there's no lights even in the instant it happens. Yeah I was think to try swapping those out since I have some spares. Its just so random and doesn't happen long enough to really notice any changes except for the couple little jerks I feel when it happens and then its fine again.

 

Is the truck carb or FI?
Check all your basics first, plugs, cap, rotor, electrical connections, vac hoses, etc...

 

It's carbed. I just finished up all that with the exception of checking a few of the vacuum lines. Cap and rotor had a little build up but I cleaned that off and all of the plugs looked good. I realized I don't have my multimeter so I'm gonna borrow my buddys to check the coil and plug wire resistance. I have a different fuel filter I am going to try putting on there and then maybe hitting it with some carb cleaner. So far nothing I have done has made any changes to the behavior though.

 

If you have a tach look at it when the hesitation happens. If it moves around it would indicate an ignition problem.

Also look at all your other guages/lights at the same time. If they all do weird things when it is hesitating it could indicate an electrical problem.

Being carb'd its probably ignition.

 

I don't have a tach and nothing at all weird happens on the dash when I feel it, there's no lights and the speedo doesn't drop or bounce because it happens so quick. I just feel a slight jerk once or twice then its fine for a while. I have a feeling its electrical as well but nothing I have done thus far has seemed to improve it. So I think I am going to start by swapping in a new coil and seeing how that works because that's the oldest part of the ignition system at this point.

 

Just throwing this in, could be the TPS sensor? I had one go bad and it was an intermittent issue that I battled on an off for several years. It did not initially throw a CEL but started when towing and cresting any incline holding throttle position.

 

My book doesn't say anything about TPS on an 85. It looks like its only on 79-83 unless its the same as the idleup diaphragm. I guess another thought I had was maybe it could be the valves? I don't know how likely that is but they haven't been touched in two years