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5.3 mpg, gotta fix that...

O

obijuan

1/2 ton status
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damn. i just drove 53 miles on 10 gallons. thats terrible.

truck is my 84 dually 454 with the quadrajet. i was pulling an unloaded car hauler half the trip though, but still! im running 3.73s with 36s right now, but on this trip picked up a 70 rear with 4.56 in it. that ought to help tremendously!

i was curious if swapping TBI onto my 84 would that help enough to justify it?
5.3 mpg is pretty bad but i dont typically drive it 53 miles a day either!

we swapped in TBI on my buddies jeep a few months ago so its probably fresh in his head but i have really no idea what i would be doing.

my tanks are also REALLY hard to get to. the bed, its not moving.
gooseneck, PTO winch, half inch plate welded in....:doah:

would i need to drop them abosolutley for sure or can i just add an inline fuel pump in the rail? both tanks switch over and everything, but only one reads on the gauge. the other is at 3 o'clock all the time. i sucks running out of gas...




SO easiest most cost effective way to get 7 mpg? id love to go to the local offroad park and not spend $200 for fuel and still be in city limits!!!!
 
thats not really enough distance to check mileage very good. Meaning that so many factors come in to play, like was it a true measured distance or the odometer reading (has it been calibrated since the bigger tires) was it a true 10 gallons...did you fill it before and after the measured distance to exactly the same point in the tank? I usually check my odometer to the mile markers on the highway over a 10 mile or more span. and do it more than once. a small change in tires size can equate to the odometer being off by .05% or more... that can make a difference over a few hundred miles, also by checking more than one tank of gas allows you to fill the tank the same each time....do you fill til the pump shuts off, do you top off a couple times, does gas run out the filler?
Consistency is the name of the game for accurate checks.
 
Filled at the beginning of the trip till I can hear it get to the filler, then did that at the end too. Google mapped my distance traveled at 53.3 miles and 9.98 gallons. It's 6.2 unloaded.
 
sounds like you need an overdrive bad....


Is the truck worth dropping in a 4l80e?
 
yeah its my favorite teeruck, but can i afford the OD lol.

ive read the 4l80/205 thread back and forth ten times and im still intimidated by a little computer.
 
The economics of swapping out an OD transmission and/or EFI are overwhelming when you only get 5MPG.

Guys who enjoy 10-12 MPG can't really justify it the way the 5-7MPG guys can....heck, if gas ever gets to $4 a gallon again the payback on so-called "expensive" swaps happens in just a few thousand miles of driving.

Holley Dominator EFI (their new EFI controller) is capable of running not only the fuel injection, but it also is pre-configured to run either a 4L60E or 4L80E tranmission as well. That's a pretty sweet bonus.... :waytogo:


:usaflag:
 
hows the truck run? I'm guessing T400, what's rpm's is it spinning on the highway? Quad seem to be tuned ok? what kinda plug readings do you get?

that's pretty bad.. even my heavily worked BB in my Chevelle got 5 mpg....
 
ryoken said:
hows the truck run? I'm guessing T400, what's rpm's is it spinning on the highway? Quad seem to be tuned ok? what kinda plug readings do you get?

that's pretty bad.. even my heavily worked BB in my Chevelle got 5 mpg....
Click to expand...


Yeah at a 1/4 of the weight though.

I'm always for EFI swaps. Just go for it. Theres lots of stand alone 4l80e controllers out there and if you have a good junkyard the 93/94 trucks (I believe thats the years) were factory with a standalone controller in diesels.
 
I say get that D70 in and run a few tanks before making any major swaps. Your current 3.73's and 36's aren't helping you any.
 
Avery4jc said:
I say get that D70 in and run a few tanks before making any major swaps. Your current 3.73's and 36's aren't helping you any.
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What you talkin about. My shortbed ran awesome with 3.73s and 36s!

O wait never mind that was with 5500 less pounds and an sm465 :whistle:
 
A friend with a 90 Dually that was purchased new,was getting only 7 mpg after a year or so,when it was getting close to 12 mpg when new...he took the truck back to the dealer several times to no avail,they tried telling him "it's normal ,for such a large engine to consume a lot of fuel (he had a 454)..

My brother looked at the truck for him,and found it was running at 165 degrees--he replaced the thermostat and the mileage doubled to 10 mpg..then he replaced the coolant temp sensor and it went up to 13..it didn't set off the check engine light or set any codes either!...
 
Stomis said:
Yeah at a 1/4 of the weight though.

.
Click to expand...

nah, not even close, i wish.... all steel 69 BB Chevelle is about 3800 lb's... tho it certainly isn't the barn door going down the highway that a K5 is... :haha:
 
ryoken said:
nah, not even close, i wish.... all steel 69 BB Chevelle is about 3800 lb's... tho it certainly isn't the barn door going down the highway that a K5 is... :haha:
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Lifted crew cab dually has gotta be around 11500 pounds. Add on the trailer and car he was towing... I know our newer duallys hit the scale at the junkyard around 9700lbs with nothing in them.
 
Stomis said:
Lifted crew cab dually has gotta be around 11500 pounds. Add on the trailer and car he was towing... I know our newer duallys hit the scale at the junkyard around 9700lbs with nothing in them.
Click to expand...

IIRC, my 97' CTD is only 7800#.
 
ryoken said:
hows the truck run? I'm guessing T400, what's rpm's is it spinning on the highway? Quad seem to be tuned ok? what kinda plug readings do you get?

that's pretty bad.. even my heavily worked BB in my Chevelle got 5 mpg....
Click to expand...



carbed 454 with a 3 speed in a one ton. trucks heavy.

truck runs fantastic, and plugs are dark carmel colored. when i mash it no black smoke comes out lol
highway speeds im at 2600 rpm
 
Yep, 7400 lbs. on mine.

I was getting around 10-11 MPG. with just the rig. That was with the new carb and the swapped in NV4500. 36" tires and 4.10 gears. Once I put the trailer on it with the blazer it dropped to about 6 maybe less. It's all of 4500 lbs for the trailer and the blazer is somewhere around 6200 lbs. Not to mention, now you're pulling a really tall brick with a brick.

Next spring i'll be switching to 4.88's and building something on the trailer to push the air up over the blazer. Oh, and removing my visor. Also going to be switching to the 37" radials.
 
Seems alot of people are getting around 7-8mpg with their big blocks. Just a nature of the beast i guess. I think your only hope to get it to 10 would be to re gear to 4.10 or 4.56 and do the over drive trans. but the cummins sure wouldn't hurt either! From what i have read about them you can get as bad as 10mpg while towing! And normally alot closer to 20mpg just cruising.
 
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