91 s10 help!!!
 

I have posted about this before but none of the info I got helped and I'm tired of throwing money at it so it's back to the experts. I have a 91 s10 2.8 5 speed it sputters and hesitates when driving and has a slight miss at idle, I checked codes and I am getting 13 and 33. The previous owner replaced the fuel pump and the regulator and put new plus and wires on it then I've put a new map sensor and o2 sensor on it it ran a little better for a few days then started again. My air filter smells like it's soaked in gas so I'm thinking it's getting too much fuel. Sorry for rambling I just want to give as much info as possible any help is appreciated

Re: 91 s10 help!!!
 

Have the catalytic converter checked ,to see if it's plugged up.
Easiest test is putting a pipe in place of the converter,and see if it still does it.
A shop will usually have a flow gauge to do it,also.
One other thing,...On my '87 that I had, the crossover pipe was a lined pipe(one pipe,inside the other),and it crushed down,choking the exhaust just enough to cause problems.
You might also check the Throttle Position Sensor,and,if it's TBI,the base gasket,under the throttle body.

Re: 91 s10 help!!!
 

Well it doesn't have a cat, didn't when I bought it and it seems to be getting enough exhaust through but I'll still check an I check the others as well this has been stumping m for over a year since I bought the truck

Re: 91 s10 help!!!
 

Check the base gasket for the TBI,then.
My boss's '93 had this happen,and it had a split in the gasket,and carbon build up.

Re: 91 s10 help!!!
 

I tried spraying around the base with carb cleaner to see if it sucked it in but nothing happened Im goon pull it off just to check it out for sure

Re: 91 s10 help!!!
 

Good idea.
We didn't find the crack,until we pulled it,as it was near the center.
Just for kicks,check the knock sensor,too.
Good luck.

Re: 91 s10 help!!!
 

Where is that? And thank you for your help

Re: 91 s10 help!!!
 

On the passenger side of the engine block.Usually round shape.
Run the engine just above idle,and tap,lightly on the engine block,with a wrench.
The engine should change the way it sounds/runs,as the Electronic Spark Control(ESC) changes the timing.
If it doesn't, replace the knock sensor,and retest,if it still doesn't react,you either have a bad ESC,or a connection problem.
The knock sensor is threaded into a "blind" hole,so taking it out,wont lose coolant,or oil.

Re: 91 s10 help!!!
 

The codes you pulled up 33 - MAP sensor signal voltage was too high (low vacuum) for 5 seconds when throttle opening was under 2%. 13 - Oxygen sensor circuit - Oxygen sensor voltage stays between 0.35 and 0.55 volts for 30 seconds when the TPS signal was above 0.55 volts. The engine had been running for at least 40 seconds with an engine temperature above 110? F.
Got this from another forum i hang at http://www.s10forum.com/forum/f107/d...-codes-198381/

Re: 91 s10 help!!!
 

So,it 's either a bad o2 circuit, or a vacuum leak at the MAP ?

Re: 91 s10 help!!!
 

Its possible to even get new parts that dont work, Ive had master cylinders bad when i bought them new... I belive there is a way to test your sensors. http://easyautodiagnostics.com/gm/2....timeter-test-1 there working on an 2.8 here so hopefully this can help out

Re: 91 s10 help!!!
 

http://easyautodiagnostics.com/gm/2....xygen-sensor-1 Heres a test for the o2 sensor.