Pirate 4x4 banner

really bad gas mileage

2K views 21 replies 12 participants last post by  mihkail 
#1 ·
Im getting horrible highway gas mileage in my bronco II with a 2.9L. I think its cause of the gears, theres no tach but the motor sounds like its at about 3k rpm doing 65mph and you really have to push it to get to 70. I know these arent known for being fast trucks or anything but i can see the gas gauge going down, not real fast but its noticeable and it has a 23gallon tank so thats alot of gas for a tiny v6... And not just highway, when i floor it on the street it uses about a 1/16th of a tank in about 2sec maybe thats normal, but ive heard of people going 475miles on one tank on the highway and i know mine wont do that.

The alignment is very bad, you can visually see that its off so i think thats probably part of the problem, im getting that fixed soon i hope. I cleaned the o2 sensor but i know i should just replace it i just did that for now. I tried injector cleaner, but ive heard an injector rebuild is really the only way to do it. I dont think its lost compression, it doesnt smoke at all and the power seems right for a motor this size.

anyone know what might cause gas mileage this bad?
 
#2 ·
I sure would like to know what people are doing to get 475 miles out of a tank of gas in a b2, because the best I've ever gotten out of my b2 was just a bit over 300 miles. And that's with 5" lift, 31's, 4.10 gears and a winch on the front.

If you're going through gas that fast, you should be blowing a visible cloud behind you.
 
#3 ·
it must be something wrong with the fuel gauge, theres no way a 2.9 can burn clean using that much gas without leaving a cloud behind. i dont even think it would run that rich either. thats all i can think of.:confused:
 
#4 ·
The fuel gauges are rarely accurate, if they even work at all at this age....

Determine milage by fillups.. not the gauge.
 
#5 ·
i'd check to see if you have an injector sticking, i had a full size bronco that came into the shop because it was running rough and was getting horrible gas milage. one of the injectors were sticking and filling the number 8 cylinder with fuel, which wound up in the crankcase.
 
#7 ·
it runs fine, doesnt rumble or rock harder than any other v-style engine ive seen... I do know the gas gauge is a little messed up, it goes past empty so maybe thats not all thats wrong with it
 
#9 ·
changed the oil a few weeks ago, the air filter was changed right before i bought it. the air filter is still white on the outside, just a little bit of black so i know its new, i checked the plugs, they look like they were changed soon before i bought it too.
 
#10 ·
Have you checked your actual gas mileage yet?

I guarantee that your guage does not function properly, as stated above. Fill your tank, reset your odometer, drive for a few days. Fill up again, then calculate your mileage. Even with 33's and 3.45 gears, I get around 17mpg. With stock tires, I got around 20mpg, maybe a little bit more if it was all freeway driving.

If you still think that your mileage is bad, replace your O2 sensor.
 
#15 ·
One of my B2s was dumping gas so fast I could not keep fuel in the tank. It turned out to be a bad fuel pressure regulator. I'd check out the fuel pressure regulator & the vacuum hose that runs to it. Pull the vacuum line off & see if their is any fuel coming from the regulator. If fuel is coming out the vacuum hose the regulator diaphragm is is bad & your getting full pressure to the injectors. If the vacuum line is leaking, not hooked up, or just not their, the pressure regulator will max out the fuel pressure and cause the fuel injectors to dump more fuel.
 
#21 ·
Taking the vacuum line off wont affect the fuel side of the regulator. If you've got to replace the regulator depressurizing the system & getting air in the system is no big deal on a gasoline system anyway ( it's like running out of gas & putting gas in the tank & restarting it ), it's not as sensitive as some diesel systems.
 
#18 ·
i took off the top end of the vaccum line, the one that goes into the brake booster cable, i didnt see any fuel in it, it looked dry. the fuel tank tube on it is slightly bent, i dont think it would matter though.
 
#20 ·
I second the stuck regulator, seen it on a buddies 2.9, the injectors were getting full pressure all the time(100psi or so), after a few minutes, the oil would smell like gas.

As for 475miles on a tank, if it is 23 gallons, I could possibly see it under perfect conditions, these things don't weigh that much..
Mine on 31's, with 3.45's got 20mpg on the highway, with a warmed up 302
 
#22 ·
i took it off on the side that goes to the brake booster, i couldnt get it off on the fuel regulator. when you say theres fuel in the vaccum line do you mean its going to pour out or just smell like gas?

where i pulled it out it looked dry, so how would i test if the line is leaking?
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top