Unless the fuel pump change on @kbuskill's fixes the problem, I suspect it will be dead. I thought I was at the end of the road, now I am pretty sure I am.
Ethanol percentage flex fuel
- Thread starter wsteele
- Start date
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Unless the fuel pump change on @kbuskill's fixes the problem, I suspect it will be dead. I thought I was at the end of the road, now I am pretty sure I am.
Right, I wasn't surprised it didn't display the transfer case control module option, as it thought it was a 6.2L. What surprised me was no error message when it didn't find the Fuel Pump Control Module and it was thinking it was a 6.2L. But as you say, maybe even the rich customers didn't get a Fuel Pump Control Module in 2007...
gooffeyguy
Tom
Try building your vehicle using the next model year and see if it's there. If not, choose the next year after that, etc. It won't hurt anything and the worst that will happen is it will show some kind of error
George B
¯\_(ツ)_/¯
I will look at mine again tonight and see if I can find a module and read pressure.
gooffeyguy
Tom
The 50-60 psi spec, is that with KOEO, or with engine running at a specific RPM? I thought that the operating psi was okay in the low or mid 40s.
Right, like always not taking the time to find the gauge, still just wasting time looking for fuel pressure on the Tech 2.
Probably should know better, given the shop manual has no mention of fuel pressure on the Tech 2, just instructs the techs to connect an old style analog gauge to the fuel rail.
I thought he said he couldn’t?
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It is the KOKO reading. It does allow for some bleed down after KO, but not much. I am out, but will look it up when I get home. If it was in the cloud, I could look it up now, but the cloud is for rich people.
gooffeyguy
Tom
It is the KOKO reading. It does allow for some bleed down after KO, but not much. I am out, but will look it up when I get home. If it was in the cloud, I could look it up now, but the cloud is for rich people.
What's this cloud? I don't use any clouds I don't think, lol
Buying one of these rigs brand new is rich!
Poor people can't afford to drive a big gas guzzling SUV? lol
I'm not rich
but I'm not poor
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gooffeyguy
Tom
kbuskill
***CAUTION*** I do my own stunts!
That fuel pressure spec is for the Flex Fuel trucks??? I have always read that the FF trucks run 43.5 psi.
OK, I understand, in post 130 he was talking about a member's 2007 that he couldn't get to display FP by telling the Tech 2 it was a 2009. So it looks like FP (and perhaps the presence of a FP module) is model year dependent.
I am not at home where I can read it, but if I remember correctly, the manual parts I was looking at didn't segregate the FF from non-FF. It had sections on FF operations, but I can't recall any heading that were FF specific. What I do remember is the key on key off pressure test was to be performed with a convention gauge at the fuel rail and pressures were supposed to be between 50-60psi with a maximum bleed down of like 5 psi after key off, after like 5 minutes. But I don't have it in front of me, so can't quote chapter and verse.
kbuskill
***CAUTION*** I do my own stunts!
I can verify that my Tech2 can see the fuel pump control module on my 2008 5.3l LMG VIN 0 flex fuel Suburban LTZ.
So I am guessing the 2007 doesn't have that option, which seems strange.
Yes, going through the same pages @gooffeyguy went through that he posted above, when I go to the Powertrain menu he has a Fuel Pump Control Module section. Mine doesn't have that option.
Frankly, I am not sure why I am so fixated on finding a fuel pressure sensor reading on the Tech 2, given the accuracy of my Ethanol calculation sensor, even if I could see it, it could be just as off as the Ethanol "sensor".
I have to spend some time looking for that analog gauge and seeing what it reads on the rail and comparing it to what the shop manual says is the right pressure.
gooffeyguy
Tom
Except the fuel pressure is an actual sensor and not a virtually calculated sensor
Sent from my SM-G930V using Tapatalk
Sent from my SM-G930V using Tapatalk
Right, my point is if the actual sensor (if I even have one that the PCM can read, seems unlikely at this point) is reading incorrectly, maybe that is why my Ethanol Virtual Sensor is incorrect. In the end, the only sure way to tell if the fuel pump is fine is to measure it the way the shop manual says to.
Given I have no engine hard starting, stutter, stumble, drivability issues, the pump is fine from a seat of the pants method of measurement. The only possible indication of a fuel pump or fuel pressure issue is the virtual Ethanol sensor calcs are way off and seemingly randomly so.
As I have said before at previous low points of this diagnosis, I suspect I may be looking at a combination of margin coding in the virtual sensor and tolerance stacking in the old gal.
What I was reading actually doesn't call out a pressure spec for engine running (at least the section I am looking at). In fact, I can't find a running pressure spec. It only says 50-60 psi for key on, then key off test. There is a pretty long and complex decision tree on leak down diagnosis, etc. In the end, if I am reading the decision tree correctly, if the on, then off pressure is above 60, replace the pump, if the on/off pressure is below 50 and none of the leak down tests are failed, then replace the pump. There is a section on low on/off pressure where they take you through dropping the tank and looking for clogged filters, strainers, feed line, etc. After all that. it seems to net down to replace the pump.
