94Z28LS1toLT1

Ok this has to be my problem that I been trying to figure out n fight,I changed everything u can think of from plugs,wires,distributor,fuel pump is new pressure is fine,fuel filter is new,I'm putting 91 in for gas.

Car hesitates n jerking when I push the gas,after fully warmed up,ok I pulled the charcoal canister out n two out of three of the hoses poured out all kinds of black pieces/pepper looking/or mouse droppings came out a lot n the canister is filed with that,now will that cause the car to jerk n hesitating,bcuz the two hoses we're filled with that crap

DelSoto

Did you get the tps issue sorted out? You mention the hesitation 'after fully warmed up'. Does it not have this behavior when cold?

94Z28LS1toLT1

Yes I replaced that tpsensor,n it's doing the same exact thing,I thought the sensor fixed it, but I left the car alone for a couple days,trying to figure out wat i didnt check,I didn't drive it long enough after I switch sensors,but the jerking n hesitating felt like it was sumtgn to do with fuel,so that's when I decided to pull the canister n the hoses off the canister n saw a lot of carbon pellets coming out the hoses

DelSoto

So when you put the pedal to the floor a scan still only shows ~50% throttle opening? Did you take the intake elbow off and see if the throttle blade was opening up all the way? You also didn't answer my question. Does it do this just when warmed up or cold as well. (I only say that because you mention this happening 'fully warmed up')

blac94Z

Need to make the TPS you changed Works for 1 and the canister has the charcoal pellets inside no liquid gas is suppose to be inside and clear all the charcoal out the lines before you fudge sumthing else up

94Z28LS1toLT1

I'm sorry yes I verified the throttle blades are opening fully with elbow off. No when it's cold it doesn't hesitate, only when fully warmed. Yes when I floored the pedal it only showed 45 to 50%

Hey TJ we will have to another log if u don't mind n see the tps again n look at everything else n see if we can give the results on the website n see wat everybody thinks,I cleared the hoses on the charcoal canister,but I'm still getting the hesitating

DelSoto

Does the tps % show 0% with throttle closed and climb to 50% as the pedal reaches the floor or is it all over the place?

You can test with a multimeter. Look for voltage between the black and blue wires with the sensor hooked up, key on (car not running). It should be 0.2-0.9v closed and around 4.5v open. Open and close the throttle slowly and make sure the voltage ramps up and down smoothly and you don't get erratic voltages, spikes, or drops.

blac94Z

DID you check the harness for breaks or opens anywhere ?

blac94Z

and yeah he floors it and it goes to about 40...50%... trying to climb slow I think the most he seen was about 60% and that was bc he was tapping the gas pedal

94Z28LS1toLT1

Thank u buddy for that info too yea wire that plugs into the sensor is good. I did another run n it's still hesitating n jerking

94Z28LS1toLT1

Delsoto I wanna check fuel pressure I assume it was fine but neglected to check it,I know it's supposed to be between 40 43 psi,but at wot what should I be at it's popping at 3500 too 4000 rpm,I check tps no spikes or anything n volts are good thank u man

94Z28LS1toLT1

Just got done with fuel pressure gauge test,it's only priming at 30 psi after the two seconds It drops slowly to 28to29psiAnd stays at that.I start it up goes to 25,then running at wot at warmed up temperature n goes to like 31-32. I did 3 priming tests all psi is 30,I already changed fuel regulator just to know it's new. So is my pump bad I hope it's the problem bcuz I've been chasing this too long

94Z28LS1toLT1

Bump

Pullngz

30 PSI is too low, is it adjustable? If so adjust it to 41-47 PSI. If not, take the vacuum line off the regulator, check for fuel in the line. If there is fuel present you have a bad regulator. What brand regulator did you buy?

If that checks out looks like you got a bad pump. What brand is it?

Thanks
Mike

94Z28LS1toLT1

Thank u Mike I changed the regulator just to be safe,it's a stock regulator ac delco it is,that vacuum line is good condition no fuel in it,I'm not sure wat u meant by adjusting it,I know it's the pump forsure then,I've never changed the fuel pump yet on this camaro yet