Truck started surging going home this weekend but if I have it more gas or barely any gas it had no issues.

Well until this one time If I was on the gas at all it was knocking, pretty bad so I didn't touch the pedal and coasted to a stop to find out my air leaner had rattled the screws loose holding it down. Fished the one out of the carb and the other out of the air filter, but they had striped. Drive slowly back the rest of the way with light surging.

Now she has a knock

Any ideas on what caused this?

 

Also it only surges in gear, as far as if the clutch is in, it had no problems at all.

 

Just guessing since I don't know what engine, carburetor, etc...

If the air filter vibrated loose, so too, perhaps, the carburetor? Especially true if on a 4.9L. This would cause a lean condition.

Check for vacuum leaks and get back with us.

 

Yes it is the 4.9.
That would explain alot.
How would I go about new screws? I'm not sure if the screw is stripped or the hole, both look ****ed up.
Just tap it?

 

Probably best to just Helicoil the holes and go with new stock size screws.

 

There are two screws attaching a flat bar which is positioned across the top of the carburetor. This is what the air cleaner attaches to with the one wingnut capped bolt. If the two screws "somewhat" work, meaning not totally stripped, I would get some blue LOCTITE and put it on the threads, tighten snugly, and allow to set-up.

These would not cause the lean mixture or surging. Check the two 1/2" nuts on the bolts which hold the carburetor to the EGR adapter/intake manifold. Quite often, they loosen. I routinely check these anytime I am working in this area. Also, the bottom half of the carburetor is attached to the top by way of 4 screws. These can only be checked and tightened when the carburetor is turned upside down. I would check the two hold-down bolts first. Be sure to not overtighten! If this does not correct the surging, next check for vacuum leaks at the normal spots [i.e. vacuum hoses, intake manifold, bottom of carburetor, PCV valve and hose, power brakes booster, etc.]. If no vacuum leaks are found [most likely, you will find one or more if this has not recently been checked], then remove the carburetor and carefully turn it upside down so that you can tighten the bottom screws. Be careful as gasoline will spill out. If you do this, be sure to replace the gaskets between the carburetor and EGR adapter and between the EGR adapter and intake manifold.

Try this and I hope it will help. Make diagrams and take photos is needed to assist reassembly.

The 4.9L engine is a great one, but really does not like vacuum leaks!

 

They both were gone. One was in the carb the other mia.
The one fell out about hundred or so miles from home so I figured no big deal, ill replace tomorrow. Then the other rattled loose and the air cleaner was just sitting ontop of the carb, about 200 miles into the trip this happens, so it had nice and hot air from under the hood.

The one screw I fished out is kind of triangular?
What is helicoil? I've heard it before just never seen or done it

 

Where did you fish these screws from? Did one fall into the engine and that's causing the knock? If it did, it's now stuck in the stop of the piston and hitting the head each time the piston comes to the top.

 

A Helicoil is a thread repair insert.
Basically a stainless steel spring with the same pitch as the screw/bolt.
You drill and tap the old hole oversize and the spring locks in place.

If your engine ate that screw a Helicoil is the last thing you need to worry about.

 

I don't think it did.

 

I fished the one out of the carb, there was a rig in there that I think prevents it from falling into it. It was caught there a good five miles that I know of.

 

The hole is striped out. A brand new 10-24 screw just pulls out of it, there's a little bit of a bite but not muchh

 

I tapped and drilled a new screw in the holes and it appears to be holding it in place.
The surging has stopped for the most part, I can barely notice it. Imma change my oil tomorrow