Sometimes you have to go back to basics. Mobile guy comeback?

Sam Mobile Technician Flint, Michigan Posted   Latest  
Case Study
Driveability
2004 Chevrolet Tahoe LS 5.3L (Z L59) 4-spd (4L60-E)
No Start
Intermittant No Crank

Just thought I would share a short story of the mobile guy that had an upset customer. That his initial diagnosis was incorrect. 1st let me say I am not perfect. When I do a diagnosis sometimes there is some feeling that this may not fix it completely. Usually its a we need to fix obvious problem a before further diagnosis can be done. 

2004 Chevy Tahoe no start. When you turn the key the starter does not run every time. Tech 2 power moding indicates that the Ignition switch may be failing. Drop clamshell do some voltage tests and confirmed the switch is bad. I instruct customer to replace the switch. Call back if there are further problems. THE CALL. Customer states. Now it is in theft mode. Injectors aren't firing. I had the shop down the street look at it also and we are convinced it is in theft mode. I can spray ether and it runs. HMM. No reason for theft as nothing has been replaced that would cause this. OK on schedule to return. 1st recheck power mode. Indicates switch is correct. When turning the key it cranks every time now. No theft light. Cluster is down. (Typical GM Cluster) HMM. I can hear pump run. Lets just start with a fuel pressure. I ask tech if he has fuel pressure gauge, and it is revealed the pump is brand new. OK. DO you have a pressure gauge? 0 PSI. I ask if it is possible it is out of gas and this is where it gets funny. He says I drained the tank to replace the pump. He is becoming pale from embarrassment. Here is the gas that was in it. Several 5 gallon cans of gas. Must've been full. He added a can of gas and now the truck runs great. 

I just wanted to share because this could have gone bad fast if I had assumed anything. As the other shop had. Sometimes you still have to check basics. 

+2
Nelson Diagnostician
Gastonia, North Carolina
Nelson Default
 

Overlooked empty fuel tank, combined with faulty fuel gauge (in some cases), is probably more common that most are willing to admit. With an arsenal of diagnostic tools, one must always start with basics as you mentioned. Most assume every driveability problem will be somewhat involved and get quickly lead down the rabbit hole. Be there myself a few times.

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Stuart Mobile Technician
Blue Island, Illinois
Stuart Default
 

I learned many years ago especially with GMs fuel guage issues,for some reason they have a history of irratic behavior,to always check if there is fuel in the tank.

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Scott Owner
Moreno Valley, California
Scott Default
 

Hi Sam, Now tell the rest of the story. The customer apologized for wasting your time and for blaming you for their mistake. They paid your normal charge for a service call... Poof - Hey Sam, it's time to get up and get ready for work...

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Funny
Jeff Technician
West Columbia, South Carolina
Jeff Default
 

sounds like that fella needs to hire Carl from sling blade lol! Funny story, thanks for the post!

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Bob Owner/Technician
East Longmeadow, Massachusetts
Bob Default
 

I will admit that I once diagnosed a fuel pump as bad but as soon as I unbolted the tank straps it became obvious what the real problem was. The one good thing about that is that it caused me to be more precise in my troubleshooting from then on.

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Randy Curriculum Developer
Raleigh, North Carolina
Randy Default
 

Ah, that moment..have had that one myself ;)

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Robert Owner
Kennett Square, Pennsylvania
Robert Default
   

We (all) certainly have had one (or more than one) of those moments . . .

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Rusty Owner/Technician
Oakham, Massachusetts
Rusty Default
 

I went to a shop once to diagnose a no-start on a V-6 DOHC Chrysler? Product that had cam correlation codes. The shop had replaced cam sensors and wanted me to figure what was going on. After an hour or so back-probing, scoping, and finding exemplar, known-good sample waveforms, I found that the cams were “in time”. I had been reaching in the open window to crank the engine so I never saw the…

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Louis Mobile Technician
McQueeney, Texas
Louis Default
 

See this all the time on heavy duty diesels, especially Cat's! Throw some sensors at it the boss says (old school way). I say nope, something else is causing the no start issue and the sensor codes are a quirk of the programming. Heated discussion, lol! More then half the time it is full issues, only about 1% of the time is it timing sensors.

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Geoff Diagnostician
Lahaina, Hawaii
Geoff Default
 

Yeah, had that once or twice out here Bob. The good news is that the tank had to come down to access the sender anyway. I sometimes wonder how the driver never noticed the gauge said full for two weeks....but then I remember they aren't paying attention to all those silly gauges....they have an iPhone to look at!

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Rex Technical Support Specialist
Alliance, Ohio
Rex Default
 

Granpa sez, "If it ain't got fuel, air and spark it ain't goona run. I don't care how many gol darn tubes* it has"..I always think of him after a "stupid". Try to think of him at the start of anything. Don't always remember. *His catch all term for modules, boards, E,P,and all CM's etc. Spark has expanded to cover basic electrical. VBat, power & ground.

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Geoff Diagnostician
Lahaina, Hawaii
Geoff Default
   

The one that got me worst last year, was when the fuel it had was just such crap it wouldn't burn. Now I preach, "if you're gonna check pressure, you better get a sample....it takes 30 seconds and may just save you the whole rest of the day"

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Bob Owner/Technician
East Longmeadow, Massachusetts
Bob Default
 

So many potential pitfalls. Have to keep your wits about you all the time.

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Geoff Diagnostician
Lahaina, Hawaii
Geoff Default
   

I tell ya, man, if it weren't for discovering iATN, a few years ago, I would have gone brain dead, like most of the car owners out here. Gotta keep READING, to have any wits at all! :-)

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Bob Owner/Technician
East Longmeadow, Massachusetts
Bob Default
 

Agree, IATN helped me to get to the next level. These days I use every resource available. iatn, diag​.​net identifix, google, youtube, facebook, oem sites, tech hotlines and anything necessary to get the job done. As time goes on it feels like there is always more that I don't know than what I do, the important thing is to be able to find the information you need when you need it…

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Geoff Diagnostician
Lahaina, Hawaii
Geoff Default
 

True dat!

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