'87 22R, Carbed 4x4 Bucking

[Mixtliboy]

My '87 truck starts and idles fine. Will begin to buck (jerk, miss etc) when quickly accelerated. If I accelerate slowly and allow vehicle to gradually gain speed, I can drive it on the hwy at 70+ mph. I have taken a can of carb cleaner to it and replaced the fuel filter. I purchased an aftermkt pump for it. But after reading some threads on this and other forums, I'm wondering if it's the pump as a factory pump was installed 9 years ago.

[mikes451]

Could be the acceleration pump diaphram inside the carb.

[jbeissner]

I have exactly the same problem with my 87 carb 22R pickup. I have replaced the fuel filter, plugs, plug wires, etc., etc. Nothing helps. As you said, If I drive it tenderly it is fine. But as soon as I start to be more aggressive with the gas pedal, it starts bucking, missing, and stalling. It has to be a fuel delivery problem. When I have time, I am planning to buy a carb-rebuild kit or or just replace the carb. Does anyone else have any other suggestions?

[mikes451]

Also might want to change the plugs and wires. I had a bad wire once that caused a hesitation and sputter while accellerating.

[auto89]

Originally Posted by jbeissner

I have exactly the same problem with my 87 carb 22R pickup. I have replaced the fuel filter, plugs, plug wires, etc., etc. Nothing helps. As you said, If I drive it tenderly it is fine. But as soon as I start to be more aggressive with the gas pedal, it starts bucking, missing, and stalling.

Just a thought.... One time I disconnected my air-flow meter and forgot to reconnect it. It behaved like you describe. Idled fine. Would start moving if I didn't open the throttle too much. But, if I opened it too much, it would cut out, stall, buck, etc.

Mine is an '89 v6. I don't remember what the device is called. It sits above the air filter and has an electronic connector. It somehow tells the EFI system how much air is flowing. Not sure if it's applicable to a v4 22r.

Mark

[sassee]

A '87 22r is carbed, not fuel injected. Have you got good fuel flow to the carb? Check the fuel pressure. If it's ok, do a visual on all of your ignition components. Pull the distributor cap off and look inside to see it it is cracked or carbon-tracked. If everything is good there, move on to your vacuum lines. Easiest way to check those is to crank your engine and spray some carb cleaner around all of your lines and around your intake gaskets and carb base. If the idle picks up, you've got an air leak.

[fasttoyotapu]

It also sounds like ignition timing issue too. Possible that it is too advanced. When it is too advanced the burn lasts too long and burns on the up stroke. When you get in to the gas, the vacuum advance kicks in and it starts bucking throwing off the whole 4 strokes. Often in those, people forget to jump the connector some where under the hood thus causing the timing to be weird.

[fourwd1]

It sounds like a fuel delivery/carb to me too.
As far as fuel pumps (as in your original post), I've found that a used Toyota pump is better than any aftermarket/remanned one. So if you doubt the pump, maybe try a new one.