8 mpg?
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8 mpg?
I recently purchased an 85 bronco II and didn't expect it to get great gas mileage but over the past two tanks i've gotten about 8mpg... thats a lot worse than i was expecting, maybe 12-15 mpg but 8... that's ferrari bad. any ideas on what could be crushing the fuel efficiency?
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also i need to replace the brakes and suspension and figure i may as well upgrade. would a suspension lift kit include the necessary parts to replace my original suspension? any specific brand or kit?
Post Fiend
Joined: Jun 2002
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From: Atlanta GA
I agree with FL1A. If it was running rich, from say a bad carb., it would be pouring fuel into the exhaust and clogging the cat. cnvtr.
If you have larger tires then normal, then the speedo might be off. The only other mechanical thing I can think of that would not be an obvious performance problem would be a slipping tranny or one that would not go into 3rd gear. 1985 should have a tach so that would be obvious.
A standard with 2.8 = 18 mpg min. with mixed driving
An automatic with 2.8 - 15 mpg min. with mixed driving
www.jamesduff.com for the suspension stuff.
If you have larger tires then normal, then the speedo might be off. The only other mechanical thing I can think of that would not be an obvious performance problem would be a slipping tranny or one that would not go into 3rd gear. 1985 should have a tach so that would be obvious.
A standard with 2.8 = 18 mpg min. with mixed driving
An automatic with 2.8 - 15 mpg min. with mixed driving
www.jamesduff.com for the suspension stuff.
Junior User
Joined: Jan 2005
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From: Memphis, TN
FYI, not all '85s had tachs, they were an option.
I'm also having bad mileage issues with my '84 with a C5 tranny, getting about 9-10. Its DS-ed with a Holley 2300 350cfm and 57 jets, so I'm going to inspect the cat this weekend and see if its plugged, reset the timing to 12 and then start jetting down to lean out the mix a little. My plugs are dark brown/almost black so that's a sign that its running rich.
I'm also having bad mileage issues with my '84 with a C5 tranny, getting about 9-10. Its DS-ed with a Holley 2300 350cfm and 57 jets, so I'm going to inspect the cat this weekend and see if its plugged, reset the timing to 12 and then start jetting down to lean out the mix a little. My plugs are dark brown/almost black so that's a sign that its running rich.
Posting Guru
Joined: Sep 2004
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From: Yokosuka, Honshu, Japan
Seems like the carbureted models (84, 85... think 86 was first year of FI?) get worse gas mileage than the "newer" fuel-injected models. Could be a matter of running rich or the choke sticking or something (stupid) as with the 2-bbl pintos. I'm not a big fan of the 1- or 2-bbl Motorcraft carbs, personally. *shrug*
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Senior User
Joined: Feb 2005
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From: Vancouver, Canada
I get about 15 mpg with my 84 BII with the C5, and I have my baby put together with brand new parts with synthetic fluids with 3.73 gears. By the way does anyone now a place the specializes in Bronco II Parts??
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Post Fiend
Joined: Jun 2002
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From: Atlanta GA
It is usually just a 20+ year old carb. that needs to be rebuilt, as to what the problem is. The max. life on a carb is usually ten years.
One big problem I have seen on carb. BIIs are the vacuum lines and Ts are bad or cracked where you can not see them. Gasket under the carb leaking can be a problem too.
> what i had to do to adjust the carb because i'm pretty sure it is running too rich.
Float adjustment, though what this means is float replacement while doing a carb rebuild if it is bad.
The best thing is to budget the $200 for a new or rebuilt. Then for $30 ($20 plus gasket and materials) rebuild yours yourself. It is pretty easy. If you mess up, get a new or rebuilt carb.
> also what do i have to do to clean out the cat?
You can not, if it is clogged you either have to hollow it out or replace it. I just use a straight pipe and skip a new cat.
One big problem I have seen on carb. BIIs are the vacuum lines and Ts are bad or cracked where you can not see them. Gasket under the carb leaking can be a problem too.
> what i had to do to adjust the carb because i'm pretty sure it is running too rich.
Float adjustment, though what this means is float replacement while doing a carb rebuild if it is bad.
The best thing is to budget the $200 for a new or rebuilt. Then for $30 ($20 plus gasket and materials) rebuild yours yourself. It is pretty easy. If you mess up, get a new or rebuilt carb.
> also what do i have to do to clean out the cat?
You can not, if it is clogged you either have to hollow it out or replace it. I just use a straight pipe and skip a new cat.
Posting Guru
Joined: Sep 2004
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From: Yokosuka, Honshu, Japan
Originally Posted by Canadianice
By the way does anyone now a place the specializes in Bronco II Parts??
www.lmctruck.com <--- lots of replacement parts, exterior and interior
www.broncograveyard.com <--- other mods, etc.
www.tomsbroncoparts.com <--- other stuff
Can't think of anything else off the top of my head. You can also check out...
www.summitracing.com for "cheaper" (than I have found elsewhere) pieces and parts, especially magnaflow / carsound hi-flow aftermarket cats.
Senior User
Joined: Jun 2006
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My 84 b2 with a reman 2150 gets right around 18-19mpg. The vaccum system on these motors are problematic at best. Your best bet is going to be new vaccum lines a cheap thing if done yourself. Also a carb rebuild would not hurt. These motors can run decently if you tune them up good and get the vaccum system leak free. I have pdf files of the vaccum lines if anyone needs them just send me a private message and Ill hook you up.
Post Fiend
Joined: Mar 2005
Posts: 8,542
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From: Louisiana
Some things that come to mind, that I'd start doing is: check the carb, possibly rebuild it, Check the o2 senser or replace it, cat is probably clogged take it off or replace it with a high flow cat(if your in a smog checking area), and check vaccum lines.
You mentioned you needed to replace the suspension, and asked if a lift kit would do it.... The answer is yes, but you'd have to get them more expensive kit with rear springs to replace the rear leaf springs. Skyjacker is a very good quality kit, and their shocks are really good too.
You mentioned you needed to replace the suspension, and asked if a lift kit would do it.... The answer is yes, but you'd have to get them more expensive kit with rear springs to replace the rear leaf springs. Skyjacker is a very good quality kit, and their shocks are really good too.
Posting Guru
Joined: Sep 2004
Posts: 1,915
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From: Yokosuka, Honshu, Japan
Cool. If you switch to even a hi-flow cat, your mpg should stay up there. I did a complete new exhaust on my Nissan with header, hi-flow cat, and 2 1/2" piping with a v-force (similar to flowmaster) muffler, and my mpg's went up 3-5 from 18-20 to 25-26 at the highest ... but that was with driving sensibly and not hot rodding it much lol 
