Fuel economy issues!?

[ryanc5413]

There ought to be a flashing MIL on the instrument cluster, for the dumping of raw fuel in at least one hole. Does it still work or is it tuned out?
How's the idle?
Is overall engine output down?
Have you pulled the plugs?
Fuel leaking anywhere?

No mil and it works. Power is not what it is of any other truck I have owned gmt400 wise. Plugs look fine. I changed them a year ago and 3 months ago they appear a tad rich but nothing to concern. Idle quality is fair about constant with gmt400s they never have had a perfect smooth idle. Atleast any I have owned. No leaks. I'm freaking so lost on this truck. I am a mechanic and own a shop but this is a true head scratcher.

 

[michael hurd]

Who knows. There are no converters so I doubt it has any. A year ago it was giving wrong economy and it still is except worse. Its not a ground. Please get out of my thread. You are not offering any one any help except bad info

Please get out of your thread?

Last I checked it is an open forum on the world wide web.

You did not post any compression test results, so I assume you haven't checked.

 

[Justin S]

I bet your front calipers are hung up.

 

[slowslowcamaro]

Check your fuel pressure regulator, more then likely leaking a common issue on cpfi.

 

[skylark]

A thread blew up that isn't about oil? Epicness

Oh and this dude needs to take his truck to a real mechanic. He's giving the rest of us a bad name. Some used car salesman calling himself a professional mechanic that can't figure out why his truck gets crappy gas mileage after putting bigger tires on and f---ing with literally everything complains that his exhaust smells like gas with no cat and a tune... Mmkay

You need to take your logic and leave!

 

[beardeddummy]

I do think it is the spider i have no cats and a tune and mine used to smell like gas until I changed that. my maf is descreened and the was tuned for it. later I was educated so I put a screened one on and mileage went from 15 to 12. I also have 285s on 3.42s. went back to my descreened maf mileage went back. as soon as I get it retuned it will be tuned for stock maf. now that I understand the whole scenario I don't like messing with the maf.

 

[DRAGGIN95]

Thread cleaned up, if it isn't helpful then don't post it, keep opinions and drama to yourself as we don't need it here!

 

[streetperf]

Just a thought, do you have access to a 4 or 5 gas analyzer? With the sniffer in the pipe the results may point you in a direction. Also what is the fuel pressure? Have you pinched off the the return line to see if there is an internal leak in the fuel system. You said the plugs look a tad rich, that should be your indicator. Have you checked the ignition system? Again the 4 gas will give you direction. These trucks are also known for the coil arcing. Have you ohm metered the igition wires. How old is the precat O2? It isn't a bosch unit by chance? You may have to start with the basics and go from there. Sometime the obvious is overlooked.

Just a suggestion. I have one of these trucks and I really have suspicion of the spider especially if there is a lot of miles on them. They do some real strange things.

 

[cookseyb]

If the coolant temp sensor is bad the computer will think it is =20 degrees and add fuel like crazy...

 

[Jrgunn5150]

The guy is gone gentleman, he punched out and left a while ago, thread is essentially DOA.