Hey guys, I have a 1988 Ford F350 Dually Crew Cab with the 460 in it. My mileage is HORRIBLE! I know these things aren't gas-sippers but I put $40 (12.77 gallons) in it when she was right about dry and i've gotten 62 miles out of it and she is sitting right above E. I know this can't be right. The truck has 87K miles, JBA ceramic headers, custom mandrel bent downpipes into a dual in/single out Magnaflow muffler and through another straight through design magnaflow, no cat or AIR pump. It has a K&N drop in filter, MSD billet distributor, Ford Racing plug wires, new plugs, etc etc. She runs great, only smells a little rich at start-up in the mornings, and no CEL's. I've been babying her around this past week too. The EGR tube isn't hooked up, it's been plugged off (the fitting in the headers was different according to previous owner who installed them). Any ideas? Also my gas gauge is weird. I can be cruising around and tap the bakes and you can watch the gauge go almost emtpy, same when I first start accelerating. It moves ALOT, and seems that everytime I get back in the truck it's a bit lower than before. I looked for leaks and can't find anything. I'm a little stumped, is 5-6mpg city normal for these things? I was hoping to squeeze 10 out of it around town babying her. How should highway mileage be? Any opinions would be great.
I've got a carb'd 460 in an 86 truck. My gas milage is probably about the same, never checked it.....but w/ a carb on a big block in a bigger truck, it's kinda expected.(even thought my father told me he always got the same mileage loaded/empty Big block trucks/smallblock trucks and that was 7-8)so I don't know why your milage is soo bad. expecailly being EFI!!!
I have the same thing w/ the gauge though. It seems like everytime I shut it off and come back to go somewhere I've lost like an 1/8 tank, sometimes more! I thought it was all in my head, so I'm glad I'm not the only one! BUT my truck did have electric fuel pumps, and I switched to mech. on the motor, and took the tanks out of my '81, that was always mech. so I didn't know if the resistance of the older fuel pickups was just different. I'dlove to find out what your gauge problem is, because I have the same problem
Ya me too, and when I brake/accel it drops a TON! I haven't done a long highway trip to see if the MPG is better that route but right now it is HORRIBLE in town. I didn't expect alot but better than this lol
If you have a 4.10 rear gear, then yeah for city driving that is about normal. Oh and all the mods you have did nothing to improve mileage. Try a dist. mechanical advance recurve and change out the carb for a standard Holley vacuum secondary 600 CFM carb. The stock carb (Holley 4180, made to Fords specs) is an emissions piece and screws up gas mileage in the process. I used a List 1850, but I had it on the shelf as a back up for the 390 in my old 1968 F250. My mileage went for 6 city and 7.5 highway to 8 city and 10 highway.
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Bear 45/70 Gimp Racing
“There are only two things stopping you, common sense and fear! And not much of the latter.”
I'm not running carb, it's EFI. I heard a few people on here say with these EFI trucks that headers and such made a bit of improvement on mileage. That and every vehicle I have ever built can benefit from them but you need to keep your foot out of it lol.
Something seems not right, probably fuel injection related... Fuel injection is junk especially on the early fuel injected systems.
My truck has a 460, with a Lunati 61602 cam (262/268 and .540/.552), E6TE heads ported on exhaust side, flat tops 9.7:1 compression, Edelbrock Performer intake, 650 CFM Holley (yeah I know, suck the butterflys down the intake... eventually I'll do a 750 or 850). Running ZF5 trans (overdrive). I get about 12.5 MPG on the highway and around town I'd roughly estimate 8-10. Truck weighs 6000 lbs and is lifted 4" rolling on 35"x2.5". Stock with 351w and C6 my truck got 17 MPG highway.
Don't worry about your fuel gauge. That doesn't mean a thing. All that matters is miles traveled and gallons burned. Not sure what to tell you since it's fuel injected. I'd raise the compression and change it to carbureted and put a ZF5 behind it, MPG should improve.
Well down the line this truck will get a whole new drivetrain and the 460/C6 will end up in a Mustang for my wife. I just filled it up yesterday so we'll see how this tank goes, I averaged right at 7mpg on that $40 last time around with all stop and go with a quick burst onto the highway just to get off one exit down. I'm not getting any codes, no smells, no leaks I can find. I'll see how this tank goes, hopefully better lol.
okay I got a ca. emissions truck and all i ever get is about 7 to 10 mpg. with the 4.10 rear and 460 it doesnt seem to make a bit of difference with the flowmaster exhaust and head work that's been done. I'm always hoping to find some miracle cure for the mpg's to get better but i got a good idea that it's not ever gonna improve by much. The only saving grace is that there's no way in hell I'm gonna spend at least 40 g's on something that will be able to tow the kinds of things i tow and since my truck is dependable it stands to reason that i need to just buy the gas which i recommend to you. Theres no substitute for cubic inches that are built to last and do the job. If you happen to find that miracle cure please let me know cuz I'd like to save $$$$ also. Good luck!
All the power you want and close to 20mpg lol. But seriously, I'm thinking your right, it's just normal. Now I have to find a way to get this thing through SMOG without spending a crap ton of money. I'm moving to florida next year where inspections aren't done but that doesn't help me right now lol, and I don't have the $400 to register it out of state right now.
Well with my 91 F-250 4X2 long bed 460EFI 3.55's I get around 11.5 to 12mpg's if I have my foot in it , I can get up to 13 if I baby it. I do about half city and half highway miles on a tank and most of the time I travel up a 5 mile 8% grade. If I'm towing heavy then mileage drops to about 5 mpg or lower but that is because I am putting more fuel in the engine. The truck only weighs around 4,300lbs. But I guess if the only driving you do is around town then I guess I could see 5 but that still seems low. I do know that if you disconnect the EGR the computer will go into a richer mixture mode because it is commanding the EGR Solenoid on but there is no movement on the EGR position sensor so maybe that is your problem. But if the PCM goes into a fixed value mode then a light should set. Does your CEL come on when you turn the key on and then shut off when the truck starts?
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2005 F-350 XLT 4X4 Dually 6.0 Auto (Parents)
1991 HD F-250 XLT Lariat
Fire Breathing 460 V-8 E-4OD
RIP 94' F-150 4X2 5.0 MAF 4R70W Super Cab Shorty Green W/ tan accent 2" front lift Flowmaster 40 3-20-94 to 6-8-05 First truck and I hit a bridge reaching for the cellular
I just reread the your original post and the way you are determining mileage is useless at best. You need to fill the tank, run whatever miles you do (the more the better) at least a half tank's worth. Now note the mileage and fill the tank the same way you did the first time. Now check your mileage. Any other way just doesn't give you real numbers.
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Bear 45/70 Gimp Racing
“There are only two things stopping you, common sense and fear! And not much of the latter.”
I've done that, but thank you. Averaged around 6.8-7.3 in town on different tanks now. Mixed highway (about 30 miles or so highway) and city I got 8.2 and ALL highway pretty much (110 miles highway about 5 city) I got 10.3 this last version of my test. I know how to calculate gas mileage. May not be a full tank all the time but it doesn't have to be if you refill at the same pointy as the previous time. And honestly unless your pulling the tank and fuel and measuring exact weights you can never be "exact" but close enough to refill times.
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