Possible engine problem

[Jimmy Simpson]

Hello, I’ve never used any forums or anything I hope I’m posting this in the right place but, I’d say about A year ago I ran into a problem with my truck. I’d say around the time I either changed the last tranny that went out or I changed my fuel pump. It started to have this hesitation upon acceleration. It’s very noticeable up hills (it prolly goes 20 up hills) and it’s somewhat noticeable on flat ground (i can just feel it hesitating not giving everything it has in the past). It idles perfectly fine, great actually. I’ve replaced plugs, plug wires, tried two carbs, changed distributor cap and rotor then the whole distributor, and if you were thinking wiped cam lobe all of the rockers are traveling fine. Everyone in my area I have talked to is baffled as well as myself so I figured I’d try here. (Btw it’s a crate 350 that was put in about 5 years ago 76,000 on it give or take a few hundred miles)

 

[dvdswan]

Welcome to the site.

 

[75gmck25]

If its an original automatic it would probably be a TH350. Did you adjust the kickdown cable when you changed the transmission? And is the vacuum modulator connected to manifold vacuum? Accleration up a hill will be bad if the transmission does not kick down and it stays in high gear.

Have someone floor the accelerator (engine off), and verify that the linkage on the carburetor is pulling the plates fully open. Also check the choke linkage to make sure it is properly disengaging the secondary lockout. If that piece of linkage sticks the carburetor will work ike the choke is still on and it will prevent the Quadrajet secondaries from opening.

Bruce

 

[MrMarty51]

Fuel filter ?

 

[Charlie]

 

[Rusty Nail]

Fuel filter ?

Is installed backwards , I bet.

 

[Jimmy Simpson]

Is installed backwards , I bet.

The last time I changed the carb I actually didn’t put a fuel filter on it because I haven’t been driving it regularly. I’ve driven it twice since then

 

[Jimmy Simpson]

If its an original automatic it would probably be a TH350. Did you adjust the kickdown cable when you changed the transmission? And is the vacuum modulator connected to manifold vacuum? Accleration up a hill will be bad if the transmission does not kick down and it stays in high gear.

Have someone floor the accelerator (engine off), and verify that the linkage on the carburetor is pulling the plates fully open. Also check the choke linkage to make sure it is properly disengaging the secondary lockout. If that piece of linkage sticks the carburetor will work ike the choke is still on and it will prevent the Quadrajet secondaries from opening.

Bruce

The modulator is connected I know that for sure because I have had trouble out of that before so I always make sure it is and by adjusting it do you mean twisting that screw in the hole of the modulator?

 

[Rick Dobbins]

Check the advance weights in the distributor. Notorious for gumming up and not advancing the spark. Easy fix: spray them with WD40 and put the rotor on and work them back and forth. Will free right up.

Also, (assuming you have a Cat converter) is the CAT plugging up? You should feel a strong exhaust pulse of air out the tailpipe. Another way to test is put a vacuum gauge on the intake source and rev the engine to say, 3000rpm. If it goes to 2in you've got a restriction. I've seen mufflers plug too, and exh pipes collapse internally (caused by steam- double walled pipe only).

An engine is nothing but an air pump: must have free flow in and out. Hope that helps!

 

[Kim Burke]

Welcome Jimmy

 

[Snoots]

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