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Function Over Form
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Discussion Starter · #1 ·
Alrite guys, I've got a 93 blazer with the CPI Vortec. I've been getting a consistent 8-9 miles per gallon, 11 mpg city and highway. Anyways, first I pulled the intake and the regulator side was a little washed but nothing horrible, but while I had it off I replaced the regulator. Still bad gas mileage. I hooked up our gm scanner at work and did the tests for everything, checked history codes, ect. EGR was operating fine, IAC system was operating fine. MAP sensor voltage low. Replaced and cleared the code, and re scanned a couple days later and that problems fixed. Oxygen sensors are operating fine. Exhaust does not smell rich or anythign(I have no cat). It runs like a raped ape, idles a little rough once in a while right at startup. I ran fuel injector cleaner and seafoamed it. My intake manifold tuning assembley is also new(broke the old one taking it out). My vaccum level is good, fuel filter has been changed less then 5000 miles ago. I always fill up every friday so the fuel level doesn't get down any farther then 1/2 a tank. I can not figure out while my gas mileage is so poor. Any other ideas? My intake air sensor and coolant temp sensor always are operating fine. I popped the Intake manifold tuning assembley again today to check for wash and there is none.
 

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how do you drive?
 

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Function Over Form
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Discussion Starter · #3 · (Edited)
Not bad enough to warrant 10mpg. And gas mileage does not change from if I drive like a grandma all week or drive like a indy car driver.

Also, distributor carp is new, rotor, wires and plugs are all new, air filter is also new. Timing is dead on(yes i unplugged the brown wire for this)
 

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Powerman said:
Not bad enough to warrant 10mpg. And gas mileage does not change from if I drive like a grandma all week or drive like a indy car driver.

Also, distributor carp is new, rotor, wires and plugs are all new, air filter is also new. Timing is dead on(yes i unplugged the brown wire for this)
Try this


O2 Sensors (bad O2's = bad mpg's) I've gain 3-4 MPG's by changing O2's
Vacuum Leaks
Tighten the carb bolts my always came loose about every 15k (idled bad).
check the air filter and air tubes for blockage.
change the fuilds front and rear diffs
change the transfer case fuilds use the addtives if needed
change transmission fuild and filter.
change oil anf filter (if you have changed oil brands change back to the brand you were getting good MPG's with)
If your do not change your oil make sure it was changed. Quick change oil places are lazy that way.
check the tire pressure.
run the correct size tires (over or under size tires may lower MPG's)
Do not idle the engine (idling waste large amounts of fuel, vortec carb was noted for that)
Do a compression test.
Regap the plugs and change to see if you have the right type (model)
 

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Nitto1320 M O D
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1,612 Posts
I know its a pain but remove the upper intake and check the platic/rubber lines that run through the intake and to the CPI (I believe its called a nut kit) turn the key and see if fuel mists from any cracks in the hose.
 

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Function Over Form
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226 Posts
Discussion Starter · #6 ·
guhman2002 said:
I know its a pain but remove the upper intake and check the platic/rubber lines that run through the intake and to the CPI (I believe its called a nut kit) turn the key and see if fuel mists from any cracks in the hose.
When I had it off for the regulator I checked them and they were fine, this was only about a month or two ago. and intake doesn't show any wash. O well I think this is just normal.... runs like a top... and the o2 sensors are good. I used the gm tech scanner and they were fine.
 
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