Truck runs rough after warmin up

[Rednek13x]

Finally got the old girl running, it will idle great all day long, when you first start it up it runs drives great. After about 2 times around the block (mile each) it starts acting up. Gets real boggy sluggish at lower rpms. If your easy and the gas you can get it to clear up and then its fine, until you shift again.

Heres a video, i have no idea what the problem would be.

Truck rough running - YouTube

[NEWFISHER]

I cant open your vid? What motor, carb, distributer etc do you have? I'm guessing based on warm under load missfire /hessitation but ok on tip in throttle will lead to low speed fuel circuit or condenser if you are running points. Check the cap for carbon tracking or cracks also.

[Rednek13x]

try refreshing the page, i had to do that worked for me. And running the 235 with points ignition. Both points and condenser are brand new. What should i check for the low speed fuel circuit.

[NEWFISHER]

Did it start to happen after you replaced the points and cond? What's the timeline and what have you done , replaced etc.
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[Rednek13x]

Truck has been sitting for 12 years. I bought it 2 years ago from neighbor. It didn't have spark so I replaced the points and condenser. Put a new kit in the carb and it fired up. I only have about 10 miles on it just running around the block. So I don't know any previous history on it.
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[SCHRUMGMC]

What do the Points look like ?

[Rednek13x]

Points look good. Could it be the ignition coil?
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[SCHRUMGMC]

Hate to hear that bud, I hope you get it sorted out soon

[NEWFISHER]

New condensers are bad out of the box new every third one. You should always carry an extra set of points and cond in the glove bo. As cheap as they are, I would grab another set and see if it helps and toss the current ones in the glove box.

Coil: http://www.ehow.com/how_7959727_test...ion-coils.html

Pull the carb back apart and blow everything out with compressed air. Make sure both top and bottom float settings are correct( they both can make a difference).

Check to make sure your vac advance is working and you plugged the line to it when you set the timing.
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[Highsider]

IMO folks want to buy a new coil for anything that happens, whether it is on a motorcycle, car or truck.
Probably because they can see it.
Rarely are coils part of the problem.

[Speedbumpauto]

Originally Posted by Highsider

IMO folks want to buy a new coil for anything that happens, whether it is on a motorcycle, car or truck.
Probably because they can see it.
Rarely are coils part of the problem.

X3! Those old engines like the mixture pretty rich when cold and will do OK on an overly rich mixture until they warm up. Also those intake/exhaust manifolds can warm up, and if slightly loose, warp and create a vacuum leak which will cause the same symptoms. When it runs bad, have someone look at the tail pipe. No smoke= lean or not fuel problem. Black smoke=rich mixture. Also, getting new points is one thing. Proper adjustment is another. Make sure the gap is set correctly. Those old engines will tolerate a lot of advance when cold, not so much when they warm up. Point gap changes timing advance, sometimes by a lot.

[Rednek13x]

Ordered a new set of points and condencor. Could this problem also be from the accelerator plunger? When I rebuilt the carb it came with the wrong plunger so I just used the old one. Which was definintly old.
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[NEWFISHER]

With the engine off, remove the air cleaner and look into the carb. Hold the butterfly open and then grab the throttle linkage and apply full throttle. If you see a nice steady fuel squirt or stream into the carb, the accelerator pump and/or diaphram is good.

[Rednek13x]

Well points looked good, so i replaced the condenser, checked the accelerator pump and that seems to be working fine also, the vac advance must be at least working, distributor moves with RPM changes. Now it seems to want to run with choke on, and will run around with that high idle speed, but when more throttle is given it boggs out and spits and sputters.

[OrrieG]

I am guessing the accelerator plunger. When I was running my stock 235 and 2BBL 283 I usually had to replace them about every 25K miles or 4 years. If you get thru the bog ok and it runs at off idle rpm under load then the advance is probably good. Like newfisher said, on the old carbs you should get a really good squirt when you open the throttle.

[Rednek13x]

Well maybe that is the problem... I wouldn't say it's a Really good squirt
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[magicoolbus]

Sounds like carby to me. I didn't catch if you rebuilt the carb?? If so, make sure the float is adjusted correctly, if not rebuilt, float could be saturated or even partially full of fuel. Also check the heat riser that it is operating correctly. Carb ice is sometimes a culprit if the riser isn't allowing heat to bottom of carb.

[Rednek13x]

I did rebuild carb. Didn't check float hight other than just looking at it and it looked pretty close to parallel. Didn't have specs for it. Also, what is the heat riser? I will now have to wait until i get my accelerator plunger comes.
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[Highsider]

Don't forget a new fuel filter.
I had an old pickup that kept dying and I had a put on a new filter and I kept swapping fuel pumps.
Then, I found a SECOND fuel filter that was plugged the whole time!
I have several interesting stories about trying to drive it during that period.

Good luck!

[Rednek13x]

I am running a dummy tank right now as mine is getting cleaned and sealed. And as far as I can see right now there is no fuel filter. Once I get my tank back I will be putting one on.
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[NEWFISHER]

Originally Posted by Rednek13x

as far as I can see right now there is no fuel filter.

This could be your problem. It doesn't take but a small piece of debris to clog the low speed idle circuit.
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[Rednek13x]

I will pull carb apart when I get back to her this weekend
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[mr48chev]

No fuel filter = any dirt that was in the gas can goes in the carb.

A lot of the old accelerator pumps had leather on the plunger rather than the rubber type material that the newer ones have and it lost it's shape after sitting dry for years.
Sometimes you can take the cup off one plunger and put it on the old one to have a fresh accelerator pump.

How many turns out do you have the Idle mixture screw turned out? I usually set them at 1-1/2 turns when I redo a carb and then set them with the vacuum gauge after I get it running and warmed up.

I'm still betting on the accelerator pump and dirt in the low speed circuit though.

[Rednek13x]

Yeah my accelerator pump is the old leather one dried and cracked up. Tried pulling the heads off but they didn't seem to want to go. I have my screw set at 1.5 turns out. What do you do or use to set it with the vacuum.
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[55dude]

Sounds like fuel,is dist advancing? Condensers have no grey area they work or fail! Good luck.
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