Hi there,

I have an 1988 Bronco with the 5.0 injection engine. The engine runs all well, but i have a feeling that the fuel consumption is very high. It consumes just above 3 litres for 10 kilometers, under mixed driving conditions. No heavy gas fot!

I am not sure how to convert this int your way of putting thing miles/ gallon. but i am under the impression that it is about 30 % to high.

Any ideas where to start looking for the cause

 

Have the engine checked for codes. You do not give us mileage or any maintenance history. Any recent tune-up's, fuel filter, air filter,plug's, wires, dist. cap and rotor. This info will help other user's to direct you in the right directions. Let us know and good luck.

 

For those of us in the USA, it works out to about 7.84 miles per gallon. This is excessive, although I'm only getting about 10 mpg with a 5.8L engine in an 87 bronco. Since your 5.0 is probably fuel injected, perhaps some of your sensors are bad and giving the computer bad info, resulting in really high fuel consumption.

 

has it always used this much fuel? if not the most logical place to start would be fuel pressure regulator or the timing.

 

I recently had this problem with my 93 Lightning.
problem was the 02 sensor not allowing ecu to stay in closed loop. un fortunately my problem crossed over two new(Bosch) o2 sensors. i couldn't get them to work until i used a new Motorcraft sensor.
during the troubleshooting, i replaced MAP sensor, fuel pump, fuel filters, plugs, wiring, cap/rotor, and installed new injectors. the Bosch units apparantly responded too slowly, and the ECU fell into open-loop and tried to cool the engine by going full rich.
we only isolated the problem using a state-of th art chassis dyno and looking at the air/fuel ratio and nox as the truck was running(loaded) on the dyno.

good luck-our hard clue was full rich AFR above 2500 rpm loaded. the afr actually fell below the machine's ability to measure(<10:1)

 

I was getting about 7MPG on my 89 Bronco w/ a 302. I replaced my Oxy Sensor and the EGR Valve/Sensor.

Just filled up yesterday and I was at 10MPG.

 

you might want to verify that the thermostat is the proper temp. i know that the memory mapping for the computer richens things up until the engine temp sensor reaches a certain value.
i live in scottsdale, and cooling for summer is a major consideration, but on my truck, at least 195 deg seems required. mine originally had a 205 deg stat. running hot in summer was cured when i replaced the plastic tank radiator with a 4-row brass one from auto zone(110$$$ cheaper than checker for same brand)
it seems to me that your 5.0 should get 12-14 mpg, unless you have really lowered the rear end ratio, or spend a lot of time in 4wd

 

Thank you all for good ideas. I´ve had the car for about 2 years and it has run this rich. There are no mods to the engine or other stuff. The only thing is bigger tires. Cooper Discoverer LT 33´

I more or less always run in 2wd.

Interesting with the engine temperature idea and the sensors.
Will erratic sensors show up on the codes?

 

you might want to visit a speedometer shop for a recalibration-the much larger tires will cause the mileage to be artifically low.
the main sensor that affects mileage is the o2 sensor. a bad one will not necessarily set any codes.
bad or dirty injectors, or ignition problems will also not set codes. the main result will be sluggish performance.
my problem was masked because i had gotten two sensors in a row which were slow to respond, and caused loss of closed loop control.
a bad temp sensor or running too cool causes the computer to go into a fuel map area which enriches mixture(cold), or really enriches mixture(too hot) in an attempt to cool the engine, and allow limp home mode.
good luck sorting this out.
for a really good article about fuel injection in general, go to http:www.chevythunder.com
it's about retrofitting chevy tpi to other chassis, but the chev fi and ford fi are extremely similar, and use the same computer chipset(OBD II)
compared to today's computers. the earlier ones are pretty dumb, but the conrol of engine functions is still very similar.

 

i had this in my 86 302. it turned out to be an injector stuck open.

 

92EXPLODER.....wouldnt that cause your engine to run differently? I mean in a noticable way. I get lousy mileage too but it has just started about 2 weeks ago.

 

invjbo , having those 33's and stock gearing doesn't help your gas mileage either. swapping to a set of 4.10 gears front and rear would put you back to stock.

late

 

yeah it ran like crap for a few days and then died. the cyl. filled with gas like hydrolock. if you turned it over with the plug out it shot out a jet of gas.

 

OK well I am just getting bad mileage...still runs fine tho

 

im getting 13 with my 351 and 31's. but the motor is a 95 351 roller cam motor so that might help a tad as well.

late