7-8 MPG...Something is WAY WRONG!!! HELP PLEASE!

[snowman74]

Howdy to everybody. Been a while since I've been on here. Computer problems. Update to those that remember...I've got all the parts for the rear of my 87' XLT after that wreck in November. I even got a new spare tire swing. Got the bumper bolted up. Getting the tailgate powder coated. Got a new window motor and new rubber gaskets etc. coming now. I got a helluva deal. Buddy of mine knows a guy that owns a salvage. I got a brand new used tailgate with ALL the guts and it works. Just needs some cleaning and a new paint job. It came with EXCELLENT GLASS. Got a new bumper with brackets. Got new taillight lenses, new drivers seat brackets ALL FOR $300. When it's all said and done, I'll have a brand new tailgate with rust free and clean guts, a new tire swing arm and bumper for less than $600!

Now to the problem. For the past few months I've noticed my fuel economy is going DOWN. Last week I put a can of Lucas gas treatment in the tank. I changed the oil and used some Lucas oil additive. I put a K&N stock rectangular air filter in the box. I put a K&N oil filter on it. I put a new tank of gas in it. The fuel gauge looked great for the first few miles. It was at 3/4 of a tank after 120 miles. Then it went to about half a tank after 50 more miles. The next day, with about 170 miles I started my day. By days end I had 225 miles and the gauge said EMPTY. Something ain't right. I've thought about everything from a leaking gas tank to the filler neck and hose to the fuel line to the injection unit. I had a new Idle air control valve put on two years ago. Sometimes when coming off a highway the RPMS only come down to about 2000 to 1500 when I put it in nuetral and pull to a stop. After I tap the gas pedal a couple of times, it comes back down to about 800 RPMS...which is normal. Also, sometimes at idle, it revs from 800 down to 400 or so and back and forth. Somtimes it DIES in the middle of a turn. I'm just lost...and before I start throwing money at it, I thought I'd ask the experts.

Part two: What can I do to replace my stock gauges? I want to build a panel that has a fuel gauge, oil pressure gauage, amperage and temp that actually work. I want good ones. Do you all know of any gauge brands that I can obtain with sender units for them?

Any help would be greatly appreciated ya'll. Thanks!!!!!!! >- Snowman

 

[bluesman17]

Heres my list of what could be bad: spark plus/wires, dirty injectors, timing, possible tps for idle and kickdown or bad fuel filters.

 

[mcbmg95]

Try the fuel filter first, I had about a 3-4 MPG increase by changing it.

 

[Justen Thomas]

I have the same problem with my 93' 351 bronco. I have changed everything, fuel filter, oxygen and map sensor... I am getting 7 mpg. It costs me $7 to go to my girlfriends house.. i dont know whats wrong. But trying changing your oxygen sensor

 

[snowman74]

Well, thanks ya'll...I've tried the fuel filter, new plugs, wires, rotor and cap. I even pulled the air tubes off the plenum and sprayed B12 Chemtool in there. I guess I'll try the injectors and O2 sensor.

How about new gauges and sending units? Anybody know some good ways to replace stock gauges? If you've got pictures, I'd appreciate them too.

BTW...got my new tailgate inner and outer glass seals today from LMC Truck. You know what those crazy sombiches did? They folded them in half to fit them in a tiny box. I called and asked what braniac did that. To their credit, they are shipping new ones out to me today without charge and without me having to send back the ruined ones.

Hope to hear from some more of you...please keep them ideas coming!

>- Snowman

 

[dozer59044]

I put 2 5/8 autometer gauges in a dash pod in my 89. So noe I have mechanical and the original guages.

 

[snowman74]

Which Autometer series gauges did you use? What Ohm range for the sender on the fuel tank? Is it difficult to install these gauges? Thanks

Snowman >-

 

[Seabronc]

Which Autometer series gauges did you use? What Ohm range for the sender on the fuel tank? Is it difficult to install these gauges? Thanks

Snowman >-

The gauge should read "E" when the resistance reaches 73 ohms, Mid scale at 22 ohms. You can test the gauge by putting a 22 Ohm resistor from Radio shack across the connector and putting the key in the ON or ACC position. Also use a 73 Ohm resistor for the E check. No connection at all will show the same as when the key is off. If that works your wires and gauge are good and the sender is bad.

>-

 

[Truck]

What powertrain set-up do you have? 302 with a Manual? My 87 got about 17 mpg, so you're definitely got something going wrong there.

How are your driving habits? Jackrabbit starts and wild stops? That'll cost gas, too.

 

[snowman74]

What powertrain set-up do you have? 302 with a Manual? My 87 got about 17 mpg, so you're definitely got something going wrong there.

How are your driving habits? Jackrabbit starts and wild stops? That'll cost gas, too.

Yes, it is a 302 manual 4 speed. 8.8 rear with the lower gearing for towing. My days of driving wild passed after I turned 30, and this vehicle hasn't been abused. I've narrowed it down to a few things...all of which are going to be replaced next week when the new parts come in:

Idle Air Control Valve, Oxygen sensor, Fuel pressure regulator, new Bosch +4 sparklers, new MSD 8.5 helicore wires, new cap and rotor. I'm even thinking about replacing the throttle postition sensor and MAP sensor...but will only do that if necessary. If all that doesn't work, I'll be begging everyone for help! I appreciate all the input!

Snowman >-

 

[wtfdissux]

you mean 7 mpg aint normal thats about what i get with a 351 and a c-6 running 33's know the feeling pass anything but a gas station and its running about 2.98 a gallon lately wondering if the new ethanol mandated by the gov. is to blame about the same time that started is when a lot of people i know started haveing mpg issues

 

[Seabronc]

I get 13 MPG right now, and plan on doing some other changes to push it up toward 20, like: carb tuning, distributor recurve, lighten up the truck, electric water pump, etc.

>-

 

[wtfdissux]

is it sixlitre from fsb that had the "plans" for the best mileage seem to remember psoting a reprint a while ago and did some of them on the 93 with pretty good results but my electrical problems and cracked rear shackle perch have it on very light duty so no real idea on what mpg is yet

 

[cliffs78bronco]

I'm with bluesman on this one.

 

[snowman74]

Howdy ya'll

Well, last week I replaced the following:

MAP sensor

02 sensor

New MSD 8.5 helicore wires

New Bosch platinum +4's

Cleaned coil terminal with contact cleaner and steel wool...very corroded

New Idle Air Control Valve

Sprayed the inside of throttle body with B-12 Chemtool

New Fuel Pressure Regulator (That was a lot of fun...try getting to those allen head screws from the bottom)

New 24k gold plated battery cable ends

Now I just need a really good way to check the fuel economy. My fuel gauge (stock) is at the empty mark...but I'm not certain it is empty. It starts and runs. No low fuel light on. I'm thinking about getting a 2 gallon plastic gas tank to take with me, and running down the highway to see how far I can go.

The engine is running NOTICEBLY smoother and staying around 800-900 RPMS at idle. The only problem is SOMETIMES, exiting a highway when I've been running at 65 MPH, when I push in on the clutch and start to slow, the RPMs sometimes stay in the 1500-2000 range. I have to kick the accelorator once or twice to get them down.

NEW QUESTION>>>>>>>>

How do you all fee about downshifting to a stop as opposed to throwing it in neutral and coasting? I know when you are towing, you should downshift...but what about regular driving?

Thanks ya'll

Snowman74 >-

 

[mbtech2003]

Howdy ya'll

Well, last week I replaced the following:

MAP sensor

02 sensor

New MSD 8.5 helicore wires

New Bosch platinum +4's

Cleaned coil terminal with contact cleaner and steel wool...very corroded

New Idle Air Control Valve

Sprayed the inside of throttle body with B-12 Chemtool

New Fuel Pressure Regulator (That was a lot of fun...try getting to those allen head screws from the bottom)

New 24k gold plated battery cable ends

Now I just need a really good way to check the fuel economy. My fuel gauge (stock) is at the empty mark...but I'm not certain it is empty. It starts and runs. No low fuel light on. I'm thinking about getting a 2 gallon plastic gas tank to take with me, and running down the highway to see how far I can go.

The engine is running NOTICEBLY smoother and staying around 800-900 RPMS at idle. The only problem is SOMETIMES, exiting a highway when I've been running at 65 MPH, when I push in on the clutch and start to slow, the RPMs sometimes stay in the 1500-2000 range. I have to kick the accelorator once or twice to get them down.

NEW QUESTION>>>>>>>>

How do you all fee about downshifting to a stop as opposed to throwing it in neutral and coasting? I know when you are towing, you should downshift...but what about regular driving?

Thanks ya'll

Snowman74 >-

use your brakes. downshifting will only wear out your clutch faster.

as for the running problem with with the high idle while driving my 351 does that sometimes but that is because of the cam that i installed. i also think that i have a vaccum leak at an injectior or 2. does it have an air mass meter or does it use speed density?? might have something to do with your problem as well. let us know.

 

[snowman74]

use your brakes. downshifting will only wear out your clutch faster.

as for the running problem with with the high idle while driving my 351 does that sometimes but that is because of the cam that i installed. i also think that i have a vaccum leak at an injectior or 2. does it have an air mass meter or does it use speed density?? might have something to do with your problem as well. let us know.

Air Mass Meter or Speed Density? I don't have a clue. Please help educate me on these. Thanks.

Snowman74 >-

 

[White90Bronco]

Yes, it is a 302 manual 4 speed. 8.8 rear with the lower gearing for towing. My days of driving wild passed after I turned 30, and this vehicle hasn't been abused. I've narrowed it down to a few things...all of which are going to be replaced next week when the new parts come in:

Idle Air Control Valve, Oxygen sensor, Fuel pressure regulator, new Bosch +4 sparklers, new MSD 8.5 helicore wires, new cap and rotor. I'm even thinking about replacing the throttle postition sensor and MAP sensor...but will only do that if necessary. If all that doesn't work, I'll be begging everyone for help! I appreciate all the input!

Snowman >-

Your gearing might be too low. Could be some cause for bad MPG.

 

[mbtech2003]

here is a web sight that will tell u the difference more that i can describe hope it helps u out on your problem /emoticons/[email protected] 2x" width="20" height="20" />http://www.fordfuelinjection.com/