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Sudden sputtering help, pls

1989 Chevy 1500 2WD 350 auto, all stock, 140k miles.

2nd owner, bought from father-in-law 2-1/2 years ago, no trouble until today. Suddenly from last time I drove it last week until today, it started coughing/sputtering whenn under a load or climbing a hill. It gets worse the more gas you give it, runs smooth at lite throttle or idle, this shows up after warm, but runs better (it seems) when choked on cold start. I really had to feather the gas pedal to get it home, but it idles just fine. Happened suddenly after being parked for a week, then started and run 5 miles, then into store and back out, it started on return trip home.

Any suggestions on where to look? I'm thinking throttle body/injector, or else fuel pump. Maybe fuel filter?

Thanks for any help.

Reply to
JG2U
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I would check fuel pressure, and if fuel filter hasnt been changed in awhile it can't hurt. Whats the weather like where you are at? If its been cold and fuel level low dont rule out water in fuel. Keep in mind no choke on fuel injection. As it runs in open loop ignoring sensors when cold which is richer than closed loop, there could be a sensor acting up. What operating tempature is the engine running? Any codes? Jump pins A and B with a paper clip and then turn key on, engine off and read codes by counting blinks of the check engine light,

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has picture of connector and pins to jump. another possablity if its been very cold is a vacumm line split. If you leave the pins jumped with the engine running you can tell if its going into closed loop when it warms up, the check engine light will blink . The rate changes when it goes into closed loop which should happen when the engine reaches about 180 degrees. Whitelightning

Reply to
Whitelightning

Maybe moisture in your fuel. Try some dryer.

Reply to
Meat Plow

bad cat

Reply to
Troy Sigwing

I second the bad cat. Mileage and age are right for that. KenG

Reply to
KENG

I hadn't even considered that... interesting. Is there a test for that, other than disconnecting?

Reply to
JG2U

Thanks... I'm in SC in the middle of our drought, no rain in 2 months. Temps warm, in the 80's this week.

I'll pull the codes tomorrow, I didn't think about that. I'm used to working on stuff too old to have a computer in them.

Reply to
JG2U

Well, no codes are stored. I'll know today if the new fuel filter and fuel treatment works.

I did check it again... cold start and driving is good, it's only when it gets warmed up that it starts bucking and cutting out under load or when you stab it. It seems more ignition related to me, but I'm no expert.

Reply to
JG2U

Problem solved. It needed new distributer cap, rotor button and plug wires. While I was under the hood I replaced the "carb" (TBI) base gasket to resolve a fast idle issue as well.

Just whose brain-dead idea was it to put the dizzy in the back of the motor crammed up against the firewall? Shit-for-brains engineering...

Reply to
JG2U

It does a good job of staying dry back there, something brain dead dizzy engineers who put them in the front of the engine dont consider on a truck.

Whitelightning

Reply to
Whitelightning

Have owned and been around those front dizzy motors for years, and have never had a wet one. Telling yourself it's in the back to help keep it dry is a good strategy to keep from cussing it, though!

Merry Christmas!

Reply to
JG2U

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