Hesitation While Accelerating

[dag8501]

I have a 89 chevrolet truck with 265,000 miles. The 5.0 has about 100,000 miles. The problem is as the subject says the truck hesitates while accelerating. It idles fine (except when cold and engauge the AC it lopes up and down), revs fine, but when I put it in gear and go it stumbles as I accelerates but runs fine once I get up to cruising speed. I have changed the fuel filter, cap, rotor, plugs, ignition coil, and have ran about a half tank of gas with seafoam. Really need help don't wont to just throw parts at the problem. Oh and the mechanic shop that said it just needed a tune up checked the fuel pressure and said it was OK. Any help will be greatly appreciated. Thanks!

[Mike G]

Welcome aboard...

 

Does the distributor and TBI have the same 100k or are they the originals with 265k on them. Could be you may need a new distributor or the trottle plate bushings on the TBI need replacing. Just a few more ideas...

--Mike

[rodram]

".... I have changed the fuel filter, cap, rotor, plugs, ignition coil, and have ran about a half tank of gas with seafoam...."

 

.... but .... did you check the condition of your plug wires???? these can be a source of random stumble and miss ... this could be consistent with your mechanic's comment about needing a tune-up????

 

... if you have replaced all these other ignition parts, it would not hurt to get a new set of plug wires...

[dag8501]

The mechanic said the wires are in good shape and don't need to be changed. They are MSD 8.5 mm wires.

[hhsrunner1]

The mechanic said the wires are in good shape and don't need to be changed. They are MSD 8.5 mm wires.

 

 

Had a similar problem with my tahoe. new dist cap and rotor and new spark plugs and the wires looked ok on the outside. But i still had hesitation and misfire on cylinder 3. I had the wires resistance checked at a shop and internally the wire on cylinder three was junk. They looked ok on the outside but inside...no good. I went ahead and replaced the whole set of wires. Misfire and hesitation is now gone.

[radiator]

Im not an expert but I would suspect the MAF sensor or TPS sensor. Is the engine light on? If so I would scan it.

[HarlanC]

my first instinct is something to do with the fuel system. Maybe a dirty Carb

[rodram]

my first instinct is something to do with the fuel system. Maybe a dirty Carb

 

if this is a stock truck with original engine then there is NO

CARB... this is a Throtle Body Injection fuel injected system

[Cliff883]

Did you ever find out the problem? My landlord and neighbor both have tbi trucks as well, and both are doing the same thing you described.

Never mind, found your other thread.

[gregrocks89]

take a multimeter and measure the resistance in each lead to be sure. Could always change your fuel filter to. If that hasnt been mentioned yet. I dont entirely read all the whole post i just sorta skim through it haha