Hi all, I have noticed in the last little while that I am burning more gas than is normal. I have not been driving any farther than usual, but my fuel consuption has basically doubled. It's getting very expensive. It's not been very cold, actually really mild, so I have not had to warm up the truck for 20 mins or so. I was thinking how an old Datsun I used to own would burn fuel like this if I forgot to push in the manual choke button, but my truck is fuel injected so I don't think it has a choke - maybe I'm wrong? It's also running very loud, almost like a roar. It's a bit embarrassing. Last months gas bill was just a bit over $600.

Any ideas???

 

Hows the shape of your exhaust system, particularly the O2 sensor?

When is it running loud? like all the time, or just at idle or...?

Any idling problems, or any other symptoms?

Also what engine do you have in your truck again, i forget...

 

Och, that is bad depending on how far you`re driving....
Try the 1987 - 1996 F150 And Larger F-Series Trucks forum, someone there is bound to have ideas though it`s hard to diagnose over the internet: 1987 - 1996 F150 And Larger F-Series Trucks - Ford Truck Enthusiasts Forums
Also the Fuel Injection, Carburetion and Fuel System forum maybe of help too: Fuel Injection, Carburetion and Fuel System - Ford Truck Enthusiasts Forums
Good luck!

 

there is a small leak in the exhaust manifold, (passenger side), but it's been there since I owned the truck. the roaring sound is there all the time now, kinda like when the ( I can't remember all the names of the parts, but on the older trucks, before fuel injection, the big cover in the middle, is it called the carburator??? - hey, I'm blonde remember), oh well, when you took the cover off, the engine would always be louder, that's the way it sounds. The engine is a 351 W, 5.8, gas, not diesel.

Because of the manifold leak, the "check engine" light is always flashing, so I'm not sure how to check the o2 sensor, or even where to find it. Hmmm

 

Ok the first thing ya should do, is clear the codes, drive it for a day or so, then check them.

These years of trucks SEEM to have cheaper electronics, sensors, wiring and whatnot in them, so its most likely a sensor somewhere that isnt allowing the computer to manage the engine right. (some way or another)

 

CODES? What codes, and where do I find them? How d I clear them, and then how do I reset them? Don't forget, I am not a mechanic, and the ones up here are pretty crappy, and charge an arm and 2 legs!

 

Here check this site out Ford Fuel Injection

Lots of good reading and great info on how to do some of that stuff!

 

Will do, Sheldon, thanks.

 

On my 94 the fuel mileage would always drop like a stone when the O2 sensor went. Which was about once a year. It is on the exhaust pipe just down from the manifold on the passenger side. You can see it from the engine compartment, you will see a plug with a wire going to it.

 

Thanks Colin. Did your engine sound deeper, or more rumbly (if that's a word haha), when your 02 sensor went?

 

I was wondering about the MAS or MAP sensor. Could this cause fuel to go up if they run a foul.
The codes are in a computer built into the truck. Yours beinga 91 you need a OBD1 code reader to figure out the problem. The OBDII are for 96 and newer vehicles.
This plugs in under the dash by the steering colunm. It will show you a code number. Once you have the code number it is a matter of reading the code from a service manual or post here and someone maybe able to decipher it.
Your next problem is where to get a code reader. I do not think you have one and your choice would be to go to one of the shops and have them read it. They will charge you a fee. It an be from $25 to $125.depending on the shops and their rates.
I'm thinking of getting one to help around here. Once I get my income tax back to go and buy one. If you had one it cxan sure save you time in solving the problems and costs on repairs.

 

There is a NAPA shop in town, I'll check and see if they carry code readers, or if they can order one in for me. I really don't want to try a shop, as they have your truck for days and it just sits there, then when you get it back, you need a 2nd mortgage to pay for it . thanks for the info.

 

You can actually pull the codes with a paper clip, if I remember right, not need for a code reader, but they do make things easier.

 

Can only use the paperclip trick if the vehicle is equipped with an engine light. Not all of the early OBDI had a light.

The MAP sensor would be a good thing to check as that is the main control for the fuel in fords SD system.

 

No nothing like that, just burnt alot more fuel.