Chevrolet Repair: 2000 s10 4.3 starts when it wants to, crank sensor, vlave


Question
QUESTION: I have a 2000 Chevy S10 4 cylinder 4.3 truck. I have been having problems with it starting some times. I would go on a Aaron and when I want to leave it would start.It only did it some times but got worse over time. I thought it was vapor lock so i would bleed the little green cap on the front of engine and it would start.That worked until last month when I came out of the store and it didn't start at all this time.I had it towed.. I changed the plugs,wires,and the fuel filter also tested the fuel pump it pumping arounf 63 psi. After i did all that I cranked it over fine and I drove strait for 160 miles home made a couple of stops turned if off gassed up got home parked it. Next day same thing,just cranks but no fire. I changed the fuel pump about a year ago and I can here it prime when I turn the key. I tired taking the gas cap off and to purge the green cap again for vapor lock, lots of fuel coming out but nothing. sorry for the book but need help truck is dead...63

ANSWER: HI GABRIEL,.WELL A 4.3 IS NOT A 4 CYL ??? THE LITTLE GREEN CAP IS A EVAP CK PORT.SHOUD HAVE NOTHING TO DO WITH A NO START PROBLEM.. THERE SHOULD BE NO FUEL COMING OUT OF THIS EVAP CK PORT.IF THERE IS SOMTHING IS GOING ON WITH THE EVAP SYSTEM..SUCH AS PURGE VLAVE STUCK OPEN ALLOWING FUEL TO GET IS IN THE LINE..THIS LINE SHOULD JUST HAVE VAPOR. IT CARRIES VAPOR FROM THE FUEL TANK NECK TO THE ENG TO REBURN SO WHEN YOU REMOVE THE GAS CAP NO VAPORS COME OUT...EMISSION CONTROL ONLY..THE ENG SHOULD STILL START EVEN IF THIS WERE GOING ON..YOU DO NOT MEAN THE FUEL LINE CK VALVE DO YOU ??? ABOUT THE NO START,WHEN THIS HAPPENS HAVE YOU EVER CHECKED FOR INGITION ????SO WHEN THIS OCCURS AGAIN CK FOR  SPARK AT ONE SPARK PLUG. THIS COULD HAVE A BAD IGN MODULE OR CRANK SENSOR ETC.. I DO NOT FEEL YOU HAVE A FUEL PROBLEM WITH THIS KIND OF PRESSURE. IF YOU COULD GET THIS ENG SCANNED FOR LIVE DATA OR CODES IN SYSTEM THIS MAY OR MAY NOT HELP,BUT WORTH A TRY.. LET ME KNOW WHEN YOU FIND OUT ABOUT THE ABOVE..GOOD LUCK TO YOU,,TOM..

---------- FOLLOW-UP ----------

QUESTION: Tom,
I haven't had a chance to check if it had spark until yesterday.. So I was going to pull off one of the plugs and check if it had spark. Before I did that I just tried for giggles to see if it would start and it fired up with no problems. I leave so I didn't pull a plug off. This morning I tried to start it again and no fire? I'm lost and I don't have a scanner to check for codes.

ANSWER: HI GABRIEL,YOU SAID YOU WENT OUT THIS AM AND NO FIRE. DO YOU MEAN NO SPARK OR WILL NOT START UP ???? WHEN YOU GET BACK TO ME I HAVE TO KNOW WHAT IT IS OR IS NOT DOING BEFORE I CAN GET YOU IN THE RIGHT DIRECTION..AT THIS POINT I WOULD NOT BE WORRIED ABOUT GETTING CODES JUST YET.WE HAVE TO KNOW IF THIS HAS SPARK OR FUEL WHEN IT WILL NOT START...GOOD LUCK, I WILL BE WAITING FOR YOUR REPLY,,, TOM..

---------- FOLLOW-UP ----------

QUESTION: I haven't had time to take out a plug and crank it to check for spark. When I did have time it started... And when I check this morning to see if it would start it did not. It would crank & crank but not start like if it had no spark of fuel. It starts when it wants to...

Answer
HI GABRIEL,OK I UNDERSTAND THIS BUT WAHT YOU NEED TO DO IS WHEN THIS WILL NOT START YOU HAVE TO FIND OUT IF IT IS A FUEL OR IGNITION PROBLEM SO I AN GET YOU CHECKING IN THE RIGHT AREA'S.
FOR A FAST TEST WHEN THIS WILL NOT START GET YOURSELF SOME STARTING FLUID AND SPRAY INTO THE INTAKE RUNNER [BY THE AIR CLEANER] THEN CRANK IT AND SEE IF IT STARTS LIKE THIS,IF SO WE KNOW IT IS A FUEL PROBLEM.IT WILL ONLY RUN FOR A FEW SECONDS AND THEN STALL AGAIN. MAY HAVE BAD FUEL PUMP OR RELAY... LET ME KNOW,,TOM..