You are here:

Chevrolet Repair/2002 gmc sierra 4.3 Intermittant NO START

Advertisement


Question
QUESTION: '02 gmc sierra 1500 2wd VIN "W" 4.3 v6 and 5spd manual 150K miles

Intermittant No-Start. When truck does start, it runs amazingly well. I have replaced several parts and am at a loss now. The truck sets NO CODES and does not have any loss of power.
However, occasionally she just wont fire up. There is no connection to engine temperature or how long it runs. The fuel pump puts out proper PSI(60-62) and of course it has plenty of spark. There are no aftermarket add-ons and runs really well when it does run. I replaced the fuel pump at the beginning of 2011.
So my mechanic is stumped and I took it to the Chevy Dealer. The first time, they couldn't get it to NOT start. Worked every time for them. The last day it was there, it wouldn't start. They told me it was the ECM ($547 installed). I couldn't afford it so I took it home. She ran perfectly for a week then the same thing. Cranks but no start. USUALLY, after a few mins (10-30) ole betty would fire up no problem. Now there is no rhyme or reason. She starts when she wants to.
Fast forward a few days and now nothing at all. No matter how long I waited. I took it to the dealer again and after another test, they've concluded it is the fuel pump ($826 installed), after they first told me its the ECM.

So now a fork in the road, one way is $600 and other way is $800 and neither way is guaranteed to fix it. Why would they switch their diagnosis? I understand this website is not a guarantee either but I need some sort of reference point. I am currently $1300 (parts n labor)into fixing this issue and am still in the same spot.

 Help me please. Make me feel better about my ole girl. I DO NOT want to sell it. Ive put too much love and effort into this truck and it runs fantastic when it does run.

any help will be appreciated... thanks for your time.
-domonik-  
Replaced: Injectors, fuel filter, crank position sensor, fuel pressure regulator, fuel pump, plugs, wires, cap and rotor, as well as cleaned up ENTIRE intake (upper/lower) manifold. I also just replaced the intake and valve cover gaskets as well as waterpump and clutch. ALL PARTS HAVE BEEN AC DELCO except for the fuel pump. I know those other things do not affect starting but I just want you to know that I buy good parts... EXCEPT for the fuel pump. I forgot the brand but would a non-Delco pump really only last 2years? Again, it puts out proper pressure running and before starting, as well as proper "leak down" after a few mins of being off.

ANSWER: HI DOMONIK,,WELL THIS SOUNDS STRAIGHT FORWARD TO ME..THANK YOU FOR GIVING ME AS MUCH INFO AS YOU DID,THIS WILL HELP ME A GREAT DEAL...AS FOR WHY YOUR DEALER CHANGED THERE MINDS MID STREAM IS BEYOND ME...THIS IS A SIMPLE PROBLEM I WOULD THINK..WE RUN INTO THIS ALOT..FIRST THINGS FIRST..WHEN THIS ENG DOES NOT START YOU OR WE WILL NEED TO FIND OUT IF IT IS A FUEL PROBLEM OR IGNITION PROBLEM..SIMPLE AS THAT..NOW IF YOU DO NOT HAVE A FUEL PRESS GAUGE WHICH MOST PEOPLE DO NOT HAVE IN THERE BACK POCKET..GO TO THE PART STORE AND GET YOURSELF SOME STARTING FLUID [JUST AS A TEST ONLY]HAVE SOMEONE IN THE TRUCK CRANKING THE ENG OVER WHILE YOU GIVE IT A LITTLE SHOT OF SATRTING FLUID THROUGH THE AIR DUCT TO THE THROTTLE BODY..NOT A ALOT JUST A SPARY. IF THE ENG WANTS TO START WE KNOW IT IS A FUEL PROBLEM. NOW WE NEED TO FIND OUT IF THERE IS POWER TO THE FUEL PUMP FROM THE RELAY OR NOT..YOU SAID ALL THE CORRECT THINGS UNTILL YOU TOLD ME THAT YOU DID NOT REPLACE THIS PUMP MODULE WITH A GM PUMP..THIS WORRIES ME,,BECAUSE WE HAVE HAD SO MUCH PROBLEMS WITH AFTER MARKET PUMPS..I KNOW YOU SAID THERE IS PRESSURE BUT WHAT ABOUT VOLUME..THIS IS OVER LOOKED VERY OFTEN. A PRESSURE GAUGE WILL NOT HELP WITH THIS YOU NEED A VOLUME TESTER. NOT MANY SHOPS HAVE THIS...BIG BUCKS !!!THIS IS WHY I WANT YOU TO USE STARTING FLUID JUST TO SEE..SO LETS SAY FUEL IS NOT THE PROBLEM AND IT WILL NOT START WITH STARTING FLUID..NOW WE MAYBE BACK TO THE IGNITION CONTROL MODULE OR,..SO CK FOR SPARK AT A PLUG BY REMOVING THE SPARK PLUG WIRE PUT A SCREW DRIVER IN THE END AND KEEP IT ABOUT 1/4 INCH AWAY FROM SOME TYPE OF METAL,CRANK THE ENG OVER AND SEE IF THERE IS ANY SPARK.THIS MAY JUST NEED A NEW COIL..THIS IS COMMON..THIS SHOULD KEEP YOU BUSY FOR A WHILE GET BACK TO ME WHEN YOU KNOW MORE...PS I WOULD CALL THE CHEVY DEALER AND ASK THEM WHY DID THEY CHANGE THERE MINDS. THIS IS NOT GOOD PRACTICE..GOOD LUCK TO YOU,,,TOM

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

QUESTION: wow, quick response! sweet... thank you for your efforts...

I neglected to tell you that I did in fact try the starting fluid method. it will start then die with this technique. It IS getting spark. the coil is approx. 5years old but seems to function properly. I checked spark on ALL wires, not just #1.

the dealer said that the fuel pump CAN ACTUALLY function normally sometimes and not others but that usually means the ECM is the culprit. THEN (2nd visit) he says the fuel pump has a bad armature. he said the ECM is sending a signal to the pump. but the pump has a "bad spot" in it.

a "Bad spot"? wouldn't there have been some sort of symptoms leading up to the issue? I thought electric motors either work or don't (barring age and wear) if they are in factory condition??? anyway, what do you think about the key's ignition switch? would that create my issue?

again, thank you for your efforts and let me know any other questions.
domonik  

Answer
HI DOMINIK, OK NOW WE ARE GETTING SOMEWHERE !! YOU SAY IT WILL FOR SURE RUN WHEN YOU SPRAY STARTING FLUID. THIS IS THEN IS MORE THEN LIKELY A FUEL PUMP ISSUE...BUT NOW WE HAVE TO PROVE THIS..GET YOURSELF A 12 VOLT TEST LIGHT AND GO UNDER THE TRUCK AND UNPLUG THE WIRING HARNESS ON TOP OR RUNNING ALONG NEXT TO THE TANK..SHOULD HAVE ABOUT 4 TO 5 WIRES  IN THIS PLUG..WITH THE KEY ON 2 WIRES MAY OR WILL BE HOT ALWAYS THIS IS FOR THE FUEL GAUGE AND ONE OTHER WIRE IS FOR LOW FUEL WARNING LIGHT,NEXT IS GROUND FOR THE PUMP AND SENDING UNIT...NOW YOU ARE GOING TO NEED ONE OTHER PERSON BESIDE YOURSELF TO CRANK THIS ENG OVER...AGAIN YOU WILL NEED TO DO THIS WHEN THE ENG DOES NOT RUN..YOU ARE LOOKING FOR A  GREY WIRE FOR THIS YEAR THIS WIRE WILL POWER UP WHILE THE ENG IS CRANKING OVER AND WILL STAY LIVE FOR 2 TO 3 SECONDS AFTER YOU RELEASE THE KEY. IF YOU GET THIS THE PUMP IS EITHER BAD OR WIRING ON TOP OF THE TANK IS CORRODED.[VERY COMMON] TO ANSWER YOUR QUESTION YES A FUEL PUMP MOTOR WILL DO THIS FROM TIME TO TIME, WORK AND THEN WILL NOT WORK..THERE MAYBE A FLAT SPOT ON THE MOTOR ARMATURE..ALSO WHEN YOU USE THE TEST LIGHT MAKE SURE IT IS WORKING GOOD.CK IT FIRST ON SOMETHING YOU KNOW IS LIVE [12 VOLTS].SO MAKE SURE YOU HAVE A GOOD GROUND ON ONE SIDE..THIS NEEDS TO WORK CORRECT OR IT WILL LEAD YOU DOWN THE WRONG RAOD...I SUSPECT YOU HAVE A BAD PUMP OR WIRING ISSUE...A IGN SWITCH COULD DO THIS BUT NOT VERY COMMON ON THIS TRUCK..THIS IS WHY WE NEED TO CK FOR POWER DOWN AT THE PUMP...IF 12 VOLTS ARE THERE THE PUMP IS THE PROBLEM.NEVER ASSUME ANYTHING UNTILL WE PROVE IT..THIS IS WHAT SEPERATES GOOD TECHS FROM BAD..NO JUMPING TO CONCLUSIONS ALLOWED...LET ME KNOW WHAT HAPPENS AND GOOD LUCK TO YOU,,,TOM....

Chevrolet Repair

All Answers


Answers by Expert:


Ask Experts

Volunteer


TOM SHEETS

Expertise

PLEASE READ ALL OF THIS BEFORE ASKING ANY QUESTIONS. IF THIS CHEVY SECTION IS MAXED OUT.YOU CAN REACH ME IN THE OLDS/BUICK SECTION. Will answer questions from 6:00am to 10:00pm all days [EST][[[ NO DIESEL OR PAINT QUESTIONS]]] will answer all 1965 to present QUESTIONS ON ALL GM'S on mechanics of these cars. Keep in mind i am not there in person i am going on what you are telling me !! PLEASE IF ASKING A QUESTION GIVE ME AS MUCH INFO AS POSSIBLE. THE MORE THE BETTER. SUCH AS YEAR,MAKE,MODEL,ENGINE SIZE. THIS WILL HELP ME HELP YOU. I will not be able to answer all questions because of some situations that i would really need to be there and see things for myself,such as electrical issues. In many cases i would need wiring diagrams. I can also give you an estimate on what the cost would be at our repair shop as an idea to help you. Keep in mind that my answer is ONLY MY ADVICE,ck with your mechanic as well.. >> THANK YOU, TOM..

Experience

I have been a ASE certified master mechanic for over 30 years and certified IN ALL 8 CATEGORIES,[engine repair,engine performance,auto trans,manual trans,clutches,steering and suspension,brakes,electrical systems,heating and air/cond. I am also a state CERTIFIED inspector for over 30 years. I do computer work [pcm]fault codes,pcm flashing,state inspection monitor readiness,repairs on exhaust,fuel service,[injection and carburetor,] charging system problems, running issues,alignments,frame problems,tire balance,struts and of course standard and anti-lock brakes.

Organizations
nys state auto repair industry and ase group.

Publications
N/A

Education/Credentials
high school,4 years of tech school,and many many hours of auto training with many gm classes and aftermarket training classes..

Awards and Honors
ASE MASTER TECH CERTIFIED IN ALL 8 CATEGORIES.NYS INSP LICENSE AND A/C CERTIFIED

Past/Present Clients
MANY CUSTOMERS IN OUR BUSY SHOP.

©2016 About.com. All rights reserved.