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Discussion Starter #1
I reset my odometer and drove for a week in hoped to calculate my fuel economy. Now I know its not an electric car so im not expecting 45 mpg. More in the ballpark of 12 maybe? Anyways I drove it lightly in city traffic and my odometer read 61 miles. My speedometer is 5% off so I really did 58 miles. It took exactly 5.8 gallons. Everything is tuned up. Airfilter, cap rotor wires plugs and timing at 10 btdc. No codes are given and I'm gonna pull a vacuum on it this weekend to look for leaks. I dont think I have any though because it runs and idles fine. And ive inspected all of the hoses including hvac. Power seems ok. I always am hoping for a little more but I think its where it should be. I pulled the vacuum line off the fpr and couldn't tell if I was smelling gasoline in the line or the rubber on the vacuum. Smelled more like gas but real lightly. Also I've yet to check fuel pressure. I'll probably do that this weekend too. Based on the info I gave what do you guys think?
 

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Discussion Starter #3
Are you running over sized or under sized tires...?
Forgot about that part. They're 31s probably worn down to 30 by now and I have 4.10 gears
 

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I think you need to drive further and fill up. Burn a whole tank of gas instead of 60 miles.
 

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Discussion Starter #5
I think you need to drive further and fill up. Burn a whole tank of gas instead of 60 miles.
Well I have two tanks. I'll just run it dry then switch to the other. Will that be more accurate or something?
 

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A 5.8 usually gets 11-13. I was getting 14-15 but drove very conservatively. For an F250 anything over 10 is good.
 

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yo Mike,

Fuel Saving Tips, General; "...Under inflated tires Increase rolling resistance 1-2 mpg; Dirty air filter Causes excessively rich fuel/air mixture 2.0 mpg; Worn spark plugs Cause inefficient combustion, wasted fuel 2.0 mpg; Worn O2 sensor Unable to detect and adjust air/fuel mixture 3 mpg; Dirty or substandard engine oil Increases internal engine friction 0.4 mpg; Loose gas cap Allows fuel to evaporate 2.0 mpg; Potential loss in fuel economy if all of the above were neglected 11.4 mpg..."
Source: by crownautopartsinc.com


CALIF REFORMULATED GAS (CARFG) - SERVICE TIP
TSB: 96-10-7
http://www.revbase.com/BBBMOTOR/TSb/DownloadPdf?id=41794

FUEL ECONOMY - EXPECTATIONS VS ACTUAL
99-26-9 for 91 F250 Revised; @ http://www.revbase.com/BBBMOTOR/TSb/DownloadPdf?id=44757
Some ok info..


Is Check Engine Light ON while driving?
Check Engine Light (CEL) comes on when the electronic engine control system is not working properly. The check engine warning indicator comes on briefly when the ignition switch lock cylinder is turned to ON, and should turn off when the engine starts. If the check engine warning indicator does not come on when the ignition switch lock cylinder is turned to ON or if it comes on while the vehicle is moving, the system is malfunctioning
If the CEL does not light up at all when starting it; then suspect that bulb is burnt-out or loose, socket was damaged by PO or shop, etc. or someone removed it, which does happen, unfortunately.

Try a Self Test for Diagnostic Trouble Codes (DTC)s by my pal, BroncoJoe19
http://broncozone.com/topic/14269-code-reader/?pid=74587&mode=threaded
A helper is good to assist in reading Codes; best is to take a cell fone vid and replay it.
Some basics;
Visual Check
1.Inspect the air cleaner and inlet ducting.
2.Check all engine vacuum hoses for damage, leaks, cracks, blockage, proper routing, etc.
3.Check EEC system wiring harness for proper connections, bent or broken pins, corrosion, loose wires, proper routing, etc.
4.Check the Powertrain Control Module (PCM), sensors and actuators for physical damage; IAC, TPS I see was replaced, etc.5.Check the engine coolant for proper level and mixture.
6.Check the transmission fluid level and quality. See E4OD Fluid Condition Check Below)
7.Make all necessary repairs before continuing
8. Check headlights

The engine temperature must be greater than 50° F for the Key On Engine Off (KOEO) Self-Test and greater than 180° F for the Key On Engine Running (KOER) Self-Test.
Run it around to heat the engine up and shift thru all gears including Reverse.

Make sure A/C is off and transmission is in Park (automatic); or in Neutral for a Manual & release clutch.

Turn off all accessories; radio, lights, A/C, heater, blower, fans, etc. (close driver's door)

Then turn off engine and wait 10 seconds.

Do KOEO test First

Post Code(s) here according to:
KOEO
&
KOER


There were a few fuel sys Recalls; were all done? Stop by local Ford dealer w/VIN ready and ask or check on-line @ Ford @ http://owner.ford.com/servlet/ContentServer?pagename=Owner/Page/RecallsPage&gnav=footer-ownersHere are two possible recalls:
Ford has recalled 1990-1993 F150, F250, and F350 trucks due to a faulty fuel pressure regulator and malfunctioning fuel pump check valves. Fuel may transfer from one tank to the second tank, causing a possible overflow condition and fire hazard. Dealers will replace the fuel pressure regulator and install redundant check valves.
Ford has extended the warranty coverage of the fuel pump and sending unit assembly in 1990-1993 F150, F250, and F350 trucks. In some trucks, the check valve may become damaged inside the fuel pump unit. This can cause fuel to travel from one tank to the other, creating an overflow condition. In the presence of an ignition source, a fuel leak may result in a fire. Dealers will repair the fuel pump and sending unit for up to 12 years or 150,000 miles from the original warranty start date.




Fuel Volatility TSB 98-26-2 for 87-96 (winter blend fuels may exhibit a stall on start up and a no restart, hard start condition or a no start condition in unseasonably hot weather...)
Source: by Ford via http://www.performanceprobe.com/ind...rmanceprobe.com/misc/tsb.php?article=98-26-02

Fuel Saving Tips
I have always factored in any cost to improve MPG in the overall $ "savings".
Free:
Reduce weight of the Bronco and tools, accessories and ... passengers; driver's get a pass; also, grille guards, side steps, etc.
Ensure that brakes are not dragging
Driving style/ light foot - Foot on da Pedal too much while accelerating and high speed driving over speed limit
proper tire pressure - Under inflated tires Increase rolling resistance 1-2 mpg;
Dirty air filter Causes excessively rich fuel/air mixture 2.0 mpg;
Worn spark plugs Cause inefficient combustion, wasted fuel 2.0 mpg;
Worn O2 sensor Unable to detect and adjust air/fuel mixture 3 mpg (not it your year);
Dirty or substandard engine oil Increases internal engine friction 0.4 mpg;
Loose gas cap Allows fuel to evaporate 2.0 mpg; P
Potential loss in fuel economy if all of the above were neglected 11.4 mpg
Check Timing
Try Sixlitre Tune-Up @ http://www.fullsizebronco.com/forum/showthread.php?t=63592&highlight=Sixlitre+tuneup&page=3

& more Items that Cost $:
alignment
tune-up. plugs - pull and check/re-gap, replace if nec, same for plug wires (check for insulation cracks, and resistance (more on this later), distributor cap and rotor
brake parts - always $ WELL SPENT

For future mods;
see;
Project M.P.G. in a Centurion 460; miesk5 Note, Results are Comparable to Tests in other Ford Engines
Source: by performanceunlimited.com @
http://performanceunlimited.com/projectmpg/
 

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Not really helpful, but my 5.0 with a 5 speed, 35's and 4.10s gets anywhere between 11 and 14 depending on how heavy my foot is that week.
 

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Discussion Starter #9
Would not having an o2 sensor affect it?
 

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What I understand is that when an O2 sensor is missing (or not functional) it will trigger a safe fuel trim for the computer to keep the engine from running lean (prevents detonation; my own worst enemy, and a good story). This safe fuel 'tune' forces the engine to run rich, which means it's pushing in excess fuel, which in turn is reducing your fuel economy. So no O2 sensor = rich running = poor fuel economy!

Cheers,
Mike
 

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i don't see what you got for milage, but my EFi 5.0 gets about 11.6MPG and needs a lot of cleaning up. Even so it seems for either motor the common MPG is around 12, as low as 10 and as high as 13. more highway, better you get (Constant speed). More city, worse you get (Start and stop)

To figure milage only use one tank:

Fill it till handle kicks out, do not tops off
Drive it to near empty. (33 Gallon tank should go about 300 miles on these)
DO NOT SWITCH TANKS
refill the tank and note how many gallons it takes
Note how many miles you drove on this single tank.

Figure MPG. repeat 3 times to get your average

Ran the numbers, 10 is low end. But 58 miles is not enough to figure on.
 

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Discussion Starter #15
What I understand is that when an O2 sensor is missing (or not functional) it will trigger a safe fuel trim for the computer to keep the engine from running lean (prevents detonation; my own worst enemy, and a good story). This safe fuel 'tune' forces the engine to run rich, which means it's pushing in excess fuel, which in turn is reducing your fuel economy. So no O2 sensor = rich running = poor fuel economy!

Cheers,
Mike
I think because it has a gvwr of > 8500 it has less strict emission laws. It passed California smog with no problem but im wondering if id see an increase in fuel mileage by adding an o2 sensor
 

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Discussion Starter #16
i don't see what you got for milage, but my EFi 5.0 gets about 11.6MPG and needs a lot of cleaning up. Even so it seems for either motor the common MPG is around 12, as low as 10 and as high as 13. more highway, better you get (Constant speed). More city, worse you get (Start and stop)

To figure milage only use one tank:

Fill it till handle kicks out, do not tops off
Drive it to near empty. (33 Gallon tank should go about 300 miles on these)
DO NOT SWITCH TANKS
refill the tank and note how many gallons it takes
Note how many miles you drove on this single tank.

Figure MPG. repeat 3 times to get your average

Ran the numbers, 10 is low end. But 58 miles is not enough to figure on.
That would probably be more accurate. Ill give it a try. Do I have to incorporate the fact my speedometer reads 45 while im going 43?
 

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My 89 with 3:55s and 39.5s got 13, my 1991 got 18-20, the 1996 gets 18-20, the 78 I haven't figured yet. Expect 15mpg with spirited driving and everything running right.

Right now my C1500 gets anywhere between 9-14 so I need to figure it out before too long...
 

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Wait, my 95 351w gets 8mpg with 3.55 gears and 33x12.5 tires....I thought that was average?
You have to take tire size into consideration. When running a bigger tire and odometer/speedo hasnt been calibrated, ur actually going MORE miles then the odometer says. So if you calculate mpg off your odometer and gallons used and nothin has been calibrated for your size tire you are traveling more miles then the odometer says.. idk if i explained that well...
 

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That would probably be more accurate. Ill give it a try. Do I have to incorporate the fact my speedometer reads 45 while im going 43?
absolutely, not because of the speed but because the Odometer will show you have gone further (Right guys? or would it show less?) Either way, yes it will be wrong.
 
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