Hesitation on acceleration

Tiny
JEB1973
  • MEMBER
  • 1996 CHEVROLET BLAZER
  • 120,000 MILES
Hello. I have a 1996 Blazer with 4.3L engine that hesitates on acceleration. Sitting at idle and punch the accelerator, engine bogs down and then accelerates. No check engine light comes on. Also, PCV valve vibrates like crazy even after I replaced it. If I pull the PCV valve off, there is lots of vacuum at idle and if I plug the end with my thumb, it will kill the engine. I have replaced the distributor cap, rotor, spark plugs, wires, fuel filter, fuel pump last year. Not sure what direction to take now. Thanks for any help.
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Sunday, September 4th, 2011 AT 6:04 AM

66 Replies

Tiny
FIXITMR
  • MEMBER
This sounds like the MAF sensor needs to be replaced. Here are two guides to help us fix the problem.

https://www.2carpros.com/articles/how-to-replace-a-mass-air-flow-sensor-maf

and

https://www.2carpros.com/articles/engine-hesitates

Please run down these guides and report back

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Sunday, September 4th, 2011 AT 6:09 PM
Tiny
BRETT_GILBERT
  • MEMBER
Thanks for this post, I replaced the MAF sensor for $78.00 and the problem is gone! I love this site.
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Saturday, December 15th, 2018 AT 12:33 PM
Tiny
BLAZER96
  • MEMBER
  • 1996 CHEVROLET BLAZER
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 163,000 MILES
I have a 96 Chevy S-10 Blazer with 163000 miles. I am having a problem with the engine stumbling and getting bogged down on heavy acceleration. When it is idling the engine runs fine without any miss or hesitation. The fuel pump has about 23000 miles on it, fuel filter about 5000, and a new spider fuel injector set. It also has a new TPS, MAP, EGR, coolant temp sensor, fuel pressure regulator, crank angle sensor, coil pack, and new plugs(plugs were put in yesterday to try to cure the problem). The timing chain was changed last summer. I have been noticing antifreeze leaking out of the intake manifold gasket and I herd that could be the problem, but never got a definate answer about it. What could be the problem. Thanks in advance.
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Saturday, December 15th, 2018 AT 12:33 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • EXPERT
That sounds like the problem. IF you have an intake leak, it will allow too much air to the engine and cause it to bog.
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Saturday, December 15th, 2018 AT 12:33 PM (Merged)
Tiny
DRSTEVEDC
  • MEMBER
  • 1996 CHEVROLET BLAZER
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 154,000 MILES
Hestitating for months. Now, will not start. Cranks but does not turn. I do not hear the fuel pump hum when I turn the key. This means full pump bad, right?
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Saturday, December 15th, 2018 AT 12:33 PM (Merged)
Tiny
RHALL77
  • MEMBER
Possible, did you check and see if you have fuel pressure. If it is your fuel pump, make sure you install a new fuel filter also
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Saturday, December 15th, 2018 AT 12:33 PM (Merged)
Tiny
OBXAUTOMEDIC
  • EXPERT
I would check Fuel Pump Relay and check to see if it has a fuel shut off switch first. The fuel shut off switch should be located in the drivers side rear access panel.

To check relay find it in the under hood Power Distibution Box. Pull it and look for the numbers on it then look at the other relays and see if any match up and just swap them then try starting the vehicle.

Smarter to check simple inexpensive things before replacing the expensive.
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Saturday, December 15th, 2018 AT 12:33 PM (Merged)
Tiny
RHALL77
  • MEMBER
Vehicle does not have a fuel shut off switch
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Saturday, December 15th, 2018 AT 12:33 PM (Merged)
Tiny
EDMONDSRMICHAEL
  • MEMBER
  • 1996 CHEVROLET BLAZER
Engine Mechanical problem
1996 Chevy Blazer 6 cyl Four Wheel Drive Automatic

I have just replaced the intake manifold gasket and have it all put back together and when I start the car it sounds like it gets to much air when I accelerate. What could have I hooked up wrong?

Michael
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Saturday, December 15th, 2018 AT 12:33 PM (Merged)
Tiny
RASMATAZ
  • MEMBER
1996 Chevy Blazer hesitation

Dirty fuel injectors (cleaning the injectors often fixes this).
Bad MAP (manifold absolute pressure) sensor
Bad TPS (throttle position) sensor
Bad or dirty MAF (mass airflow) sensor
Low fuel pressure (leaky fuel pressure regulator or weak fuel pump)
Vacuum leaks (intake manifold, vacuum hoses, throttle body, EGR valve)
Bad gasoline (fuel contaminated with water or too much alcohol)

Sometimes, what feels like a hesitation is actually ignition misfire rather than lean misfire. The causes of ignition misfire may include:

Dirty or worn spark plugs
Bad plug wires
Weak ignition coil
Wet plug wires
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Saturday, December 15th, 2018 AT 12:34 PM (Merged)
Tiny
MINICYCLES123
  • MEMBER
  • 1996 CHEVROLET BLAZER
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 143,000 MILES
Hi Ive got 96 S10 Blazer 4.3 motor. Check engine lite was on.I think it was a PO101 or 102.I cleaned the throttle body. Was ok for a couple days. Now has slight hestitation when first starting out in the morning. And no codes. Any ideas? Thanks Guys
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Saturday, December 15th, 2018 AT 12:34 PM (Merged)
Tiny
RHALL77
  • MEMBER
Check and see if you need a tune up like a cap and rotor and fuel filter. Check for carbon tracking in the cap and see if your fuel filter is plugged up.
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Saturday, December 15th, 2018 AT 12:34 PM (Merged)
Tiny
JAREDWILSKE6185
  • MEMBER
  • 1998 CHEVROLET BLAZER
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 175,000 MILES
I have a 98 chevy blazer. I have been scouring automotive repair websites and have seen many blazers running into this problem. When the truck is cold it hesitates badly sometimes almost to the point of stalling out it seems but never quite gets there. I just had a full tuneup and have taken it into the shop 2 times already and the mechanic cannot figure out whats going on. As soon as it warms up (About half an hour of driving) it runs great. I just had my fuel pressure checked and it read at 55. The weird thing is that the computer is not throwing any codes at all, had it scanned twice. Cleaned the maf sensor and that didnt work, also had the Idle air control valve cleaned but not replaced, thinking about the coolant temp sensor but Im not sure if thats it. Please can someone clear this up for me once and for all!
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Saturday, December 15th, 2018 AT 12:34 PM (Merged)
Tiny
JACK42
  • MEMBER
Fuel pressure for your vehicle should be from 60-66 psi, anything less wont run properly. Does the pressure change when you rev the engine?
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Saturday, December 15th, 2018 AT 12:34 PM (Merged)
Tiny
JAREDWILSKE6185
  • MEMBER
Im not sure if it changes on rev, but from what youre telling me it sounds like my fuel pump might be going bad? I just had my fuel filter replaced so that cant be it. Anything else to try before I start into my fuel pump?
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Saturday, December 15th, 2018 AT 12:34 PM (Merged)
Tiny
JACK42
  • MEMBER
Low pressure is the pump, if the filter has been changed. The pressure should increase a little on therev if the regulator is working right. I do suggest an A/C Delco pump though
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Saturday, December 15th, 2018 AT 12:34 PM (Merged)
Tiny
JAREDWILSKE6185
  • MEMBER
Is there any kind of test I could do to make sure that my fuel pump is going out before I go spending the 300 dollars to buy a new one?
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Saturday, December 15th, 2018 AT 12:34 PM (Merged)
Tiny
JACK42
  • MEMBER
Basically if the pump doesnt put out the pressure and the filter is new, the pump is all that is left
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Saturday, December 15th, 2018 AT 12:34 PM (Merged)
Tiny
PAULNC57
  • MEMBER
  • 1989 CHEVROLET BLAZER
Engine Performance problem
1989 Chevy Blazer

Vehicle runs fine most of the time but suddenly will start stumbling (like suddenly lean mixture. Includes the occassional backfire in carb). I have changed the fuel filter (it acts like a dirty fuel filter) but problem will suddenly appear even now. Suggestions?
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Saturday, December 15th, 2018 AT 12:34 PM (Merged)
Tiny
JAREDWILSKE6185
  • MEMBER
Ok, so would this be something that a weekend warrior could do or would this be a shop only deal, because I know that the pump is in tank so. I wouldnt even know where to start.
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Saturday, December 15th, 2018 AT 12:34 PM (Merged)

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