QuestionWell I solved the problem. I thought that since this guy had the wires crossed that it had to be running rough. Most drivers in america think that when a car runs rough it is water in the gas. Sure enough the guy put 4 cans of some gas additive in the tank. I pumped a gallon of gas from the bottom of the tank and it looked like mellow yellow soda. Afterward I started it and left it run for about an hour and low and behold it runs like a truck again.PLEASE PASS ALONG THE IMPORTANCE OF CONSIDERING FUEL CONTAMINATION AND THE FULL INFO FROM THE CUSTOMER ABOUT WHAT HAPPENED. IT MIGHT SAVE YOU A FEW DAYS OF DIAGNOSTIC TIME.THANKS JUSTIN KARLINCHAK-------------------------
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Followup To: The customer said his brother only tried to tune it as it had 100,000 miles on it without ever being tuned up. He said it had no problem until the drive home from North Carolina. I checked that first I am just so frustrated that I forget to mention it. It doesn't just stumble it is like a rev limiter you can feather the throttle and get maybe 2500 rpm without it in gear and then you can push it to the floor and it doesn't go much further. That is why I unhooked the convertors it acts just like a clogged one. I pumped some fuel into a bottle and it looks very bright yellow? I was starting to think maybe someone put some diesel fuel into it as this company has both types of trucks. Usually when they come in here with diesel fuel they won't start at all or when hot. Any other ideas? Thanks for the reply. (Frustrated in Virginia) Justin Karlinchak
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I am the shop foreman of a small all makes repair facility in Arlington Virginia. We have had this truck a 2000 chevy venture 3500 conversion box truck with a 5.7L central fuel injected engine here for a week now and even with my 28 years experience I have not been able to figure it out. It came in with the spark plug wires crossed and coil and 3 of the wires arcing to the valve covers. I replaced plugs, wires, coil, cap and rotor. And substituted a know good maf, map sensor and temp sensors from a truck that ran perfectly. I scoped a few things out and found that the cam position sensor had drop outs when it was missing so I replaced it also repaired the charging system which was not functioning properly. The thing idles perfectly now but still falls on it face when accelerated in or out of gear. I even put a fuel pressure regulator on the spider style fuel injector unit. No codes all the readings on the scan tool look perfect. I have checked the compression it is fine. The vacuum drops off when it starts loading up but the other truck we have that runs perfectly does the same thing when you accelerate. The ignition patterns look good on the scope. Checked the fuel pressure and it was approx 60 psi. I have disconnected the exhaust it makes no difference. Any help would be greatly appreciated. This is causing a big riff between me and my Boss. Thanks Justin Karlinchak
Answer -
You stated:' It came in with the spark plug wires crossed and coil
I have NO clue as to what you are asking here.
What mechanical work has been performed on the vehicle recently ?. As most problems that occur after a recent repair was made can be traced back to the area of where the repair was made.
Don't OVERTHINK the problem. What would you normally suspect IF the vehicle was NOT computer controlled ?.
What causes a carburated vehicle to stumble ?. Accelerator pump and or no ignition advance.
Manually using your OHM metr test the TPS and check the spark advance with your timing light.
Let me know what you get.
You have a simple problem and your overthinking the solution.
autohelp
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Did you find your problem yet ?. I have a long lengthy test list from all my many years of notes and some of them are quite interesting and you need to do the tests.
What was your fuel pressure again and what is factory specs ?.
autohelp
Contact me at:
meperganfortis@msn.com
While I pull some notes on ODD driveability problems that I have had over the years and I can give you numerous possibilities and things to test.
autohelp
AnswerI am glad to hear you found your problem. The reason that I did not get back to you the otther day was that I was in the middle of typing out some ODD problems from my old and newer notes and one of my major concerns was your yellow fuel color. I had typed that you bypass the fuel tank and using a portable fuel injector flushing statin that you run a mixture of cleaner and KNOWN GOOD fuel thru the cleaning station of which has it's OWN adjustbale electric fuel pump and see how the engine performed. I also was going to have you test for fuel vs additive seperation via alcohol content plus some other off the wall tests.
However, We had a major power outage due to a recent snow storm, Which is RARE for this part of the country and I was dead and COLD for quite some time before the power came back ON.
I lost about 30 minutes of typing my procedures to you, Which is wh, Once the power came back ON, I thought I had better ask you if you found your problem BEFORE I went and re-typed all the information AGAIN and then afterwards finding out that you found the problem.
GOOD WORK. Lesson well learned. Keep a note book or keep all these ODD problems stored in your computer. I have a notebook for every year with these ODD problems that I finally resolved and it STILL comes in handy after all these years.
I would be willing to bet that your boss never even appreciated all the time, effort and lost money (if your on commission) that you spent on this vehicle. Most have no appreciation or comment UNLESS you make a mistake, Then they are all over you like a circus tent.
Back to what I said much earlier, DON'T OVER THINK THE PROBLEM.
autohelp
