Truck runs rough, help!

[Bean]

Sounds like the timing is off or the carb isn't tuned properly!

 

[Zoomalot]

I noticed you added Trans. type as being a Turbo 350.
I am finding that would be an unusual Trans for a "85"-305 engine.
Trucks in those years from I believe "82" on used a lock-up converter Trans being I believe 700R4.
I stand to be corrected but it may be a clue to the problems!!

 

[Johnathan25]

Just a couple of ideas...
You mentioned no smog, but if the converter is still on... It may be partially clogged.
Also:
Could be faulty power brake check valve (If equipped)
Could be Vacuum line disconnected from Transmission Modulator (If equipped)
Could be rounded-off (Worn) cam lobe
Could be loose or jumped timing chain
>>With engine cold turn the crankshaft (Using a 5/8 socket) back and forth to see if there is excessive play)<<
Good luck!

Update: Checked all of this, no problems with any of it. It seems like it’s starting to get slightly worse every time I drive it.

 

[Johnathan25]

I noticed you added Trans. type as being a Turbo 350.
I am finding that would be an unusual Trans for a "85"-305 engine.
Trucks in those years from I believe "82" on used a lock-up converter Trans being I believe 700R4.
I stand to be corrected but it may be a clue to the problems!!

You know, I’ve thought about that because it did seem odd to me that it didn’t have a 700R4, but it definitely has a th350. I’ll look into that, maybe a previous owner switched the trans.

 

[Goodguy]

How new are the components in the distributor? Ignition coil? Module? I have ZZ3 crate engine in my street rod. The under hood heat takes out the module once a year. When this happens it is hard to start and runs like a pooch. Eventually it will not start. I also lost a pickup coil. It would run fine when cold and then felt like I was tapping the brakes when running down the road.

 

[scscomp]

Check timing. Symptoms sound like it may have jumped timing. With that many miles, it's time for a new timing chain anyway.

 

[bucket]

I don't remember the last year for the th350, I thought it was '85 though. My '84 came stock with a th350. The 700 was still an option.

 

[Johnathan25]

How new are the components in the distributor? Ignition coil? Module? I have ZZ3 crate engine in my street rod. The under hood heat takes out the module once a year. When this happens it is hard to start and runs like a pooch. Eventually it will not start. I also lost a pickup coil. It would run fine when cold and then felt like I was tapping the brakes when running down the road.

All components of the distributor except the distributor itself were replaced within the past month or so.

Also, I’ve checked the timing numerous times and the timing is fine.

 

[Johnathan25]

Update, it just started earlier today to where it wants to take 5+ seconds before it engages when put in reverse.

 

[bucket]

Update, it just started earlier today to where it wants to take 5+ seconds before it engages when put in reverse.

My '84 did that. It got slower and slower over the years. Eventually it would only go into reverse after it was driven and fully warmed up.

But check the fluid though, if you haven't already.

 

[Johnathan25]

My '84 did that. It got slower and slower over the years. Eventually it would only go into reverse after it was driven and fully warmed up.

But check the fluid though, if you haven't already.

Checked fluid, looked good.

 

[scscomp]

Update, it just started earlier today to where it wants to take 5+ seconds before it engages when put in reverse.

This is going to sound wacky but, my TH350 started slipping badly in first and reverse. I was told the front pump was going bad. I put some Lucas Oil Transmission Fix in it three years ago and it hasn't slipped since.

 

[scscomp]

Also, I’ve checked the timing numerous times and the timing is fine.

It's that "it happened all of a sudden" thing you said that tells me it's timing. Does the timing mark stay steady or does it jump around when you check it?

 

[Johnathan25]

Update: Lucas transmission fix fixed the problem where it wouldn’t engage when put in reverse. However the truck is still acting up. Also in regards to the timing, it’s fine, I’ve had it checked by a mechanic buddy of mine and he said it was all good too. He cannot put his finger on what this problem is either though.

 

[Johnathan25]

Update, it has started now to where it won’t crank up more and more frequently.