j3h

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?

Teuf

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.....

j3h

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.

offroadnutz

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

j3h

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.

offroadnutz

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.

j3h

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.

ThorInc

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.

j3h

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