94 GMC Jimmy hesitation problem

[shanes76]

I just got this Jimmy, it has the 4.3 vortec, it has a hesitation after stopping and trying to accelerate, but it seems after it gets the gas flowing it takes off, and also sometimes when you go to shut it off it wants to keep on running. The MAP sensor has been changed, and I believe 4 of the 6 plugs have been changed(found 2 new ac delco plugs in door) and when starting it has to turn over for about 4 or 5 seconds before it starts and seems a little rough then kinda smoothes out, idles fine though. Check engine light is on but havent got anywhere to pull the codes( can this be done like a camaro where you use a paper clip?) But once you get past that hesitant spot it runs fine, and I did kinda smell some gas fumes after starting it. I know the converter or exhaust is not restricted because it has the down pipe and a cherry bomb then another piece of pipe and thats it. Any suggestions? Thank you in advance

[MT-2500]

Yes jumper pin A & B and read codes and post back codes.
Then clear codes and recheck.

Run a fuel pressure check for lose of pressure.
Post back fuel pressure readings.

I would also get the other two plugs in it.

On running after shut off is the idle rpm high?
What is idle rpm?

[shanes76]

codes were
12
33
35
43
45
after getting codes I tried starting it and it fired right up, runs rough at first then smoothes out was idleing what seems alittle higher than a normal idle but maybe becuae its cold

[shanes76]

when the guy put the map sensor on and didnt reset the codes- would that affect it?

[MT-2500]

Yes codes should be cleared and recheck for what comes back.
Clear and post back if any coms back.

What was bad on old map sensor?

Make sure new map sensor has good vacumn tomit and is working good.

45 is rich exhaust that can be caused by map sensor or wiring or vacumn to it.

Post back any codes that come back after code clear.

[shanes76]

I'm not sure what was bad on old map sensor, he just said he put a new one on

[MT-2500]

Clear codes and post back what codes back.
Watch the map voltage sensor reading to pcm.

[shanes76]

I need to make a correction from my first post and I want to apologize for this- the MAF sensor was changed but I originally posted that the MAP sensor was the one that they changed- so MAP sensor has not been changed

[MT-2500]

Originally Posted by shanes76

I need to make a correction from my first post and I want to apologize for this- the MAF sensor was changed but I originally posted that the MAP sensor was the one that they changed- so MAP sensor has not been changed

No problem.
Clear codes and see if any come back.
If so post back code no.
And check that fuel pressure.
And post back fuel pressure readings,

[ericn1300]

a cold start misfire with that collection of codes and I'd be looking at the distributor for the problem.

[blazes9395]

I was just reading this and noticed it was a '94, most likely engine code W. This engine does not have a MAF sensor. As the others mentioned, i would be looking at the distributor and if that checks out, another problem area is the injector/regulator. A fuel pressure test would be a good start, as was mentioned too.

[shanes76]

it has a new cap and button on it, every once in a while when driving I get a small gas smell and sometimes a small antifreeze smell

[shanes76]

Also, it says the MAP sensor voltage is too high which would mean low vacum- and if there is no load or slight load(like taking off from a stop) until speed was achieed it would have high vacum- but if there is a vacum leak it would have low vacum at idel but making the sensor think there is no vacum( am I right so far?) and the reason I am posting this is because after you get a little speed it does not hesitate at all and after I drive to work( which is an hour away) and you stop and take off it doesnt hesitate, doesnt really start hard either, I went out yesterday and it fired right up. I havent done the feul pressure test yet because I dont have the guage or the money to buy one, Im going to advance auto today to have the codes rechecked and reset so I will repost them tonite

[shanes76]

went to Autozone and they said they can check 96 and up

[blazes9395]

Use the paper clip method to get your codes, like MT mentioned.