can't figure out why I use so much fuel..

[siege]

Well I still can't figure out why I am using so much fuel. I'm not sure of the exact mileage cause my speedometer doesn't work, but its around 10mpg. It used to be around 16-18mpg until I changed headgaskets and valve springs last October (car sat for about 4 weeks without being started during that time). anyway, I pulled the codes and got an 82 which, correct me if I'm wrong, is from the smog pump being removed (if its not, wtf is it). I then dumped some UV dye in the tank and searched for a leak and came up dry. I just pulled some plugs and they're white as a ghost which would indicate a lean condition. so I'm stumped. On the first start of the day it generally surges and stalls about 45 sec or so and just reeks of gas. and generally when I get wherever I'm going I can still slightly smell gas after the car is off.

anybody got any ideas? I need to get emissions done next month so I'm trying to get this stuff figured out before then. thanks guys

 

[88stangmangt]

what did you do with the charcoal canaster lines? you might get away without haveing that air pump on with the emissions. i would try some fuel injector gas treatment and some throttle body cleaner. dirty injectors kill power as well as fuel milage.

 

[siege]

the canister and lines are still connected. I guess I'll grab some injector cleaner tomorrow before I get gas.. thanks

 

[jrtcarter]

I was having these same symptoms and found that I had an injector stuck open.

 

[siege]

I was having these same symptoms and found that I had an injector stuck open.

how'd you figure that out?

 

[jrtcarter]

I didn't. I took it to a buddy of mine and somehow he found the back injector on the drivers side to be stuck open. They were the stock 19# injectors so I went ahead and upgraded to 30# and got a 75mm Pro M mass air. I haven't had any trouble since, so I guess he was right.

 

[89MustangGX]

If your speedo is off, there's not a real accurate way to check mileage. ???

 

[siege]

If your speedo is off, there's not a real accurate way to check mileage. ???

nope. your odometer works off your speedo cable, which in my situation, doesn't work at all. if your speedo reads faster than you are going, your actual mileage will be less than the odometer says, and vise versa. blah blah, that should help

 

[88stangmangt]

how is your fuel level sender? still holding up?

 

[Black Sun 5.0]

I'm having the same problem and I'm suspecting an injector issue. But the question remains: how does one tell that an injector is stuck open? I done almost everything on my car to fix a poor mileage issue. Yes, swapped O2's, ran codes, etc. My mileage started sliding after I had my heads swapped, but it was a gradual decline and may have started before the heads were done. Damn this issue! It seems like every other guy on this board has a similar problem! :damnit:

 

[shawn13]

A good shop can test them for a fee But if I get 10 mpg in my 89 gt jumping for joy my bronco get 12 my boat gets 5gal per mile it seams any way call a good shop they can help at times

 

[ninety15.0]

Just a thought bu you might want to check or replace your fuel filter, change your pcv valve and clean your air filter....if u havent done this in a while....clean your MAF and your TB...basically go through it and give her a nice little tune up...im sure u will see a difference. good luck

 

[Black Sun 5.0]

In my case, it's all been done.

 

[jrichker]

I'm having the same problem and I'm suspecting an injector issue. But the question remains: how does one tell that an injector is stuck open? I done almost everything on my car to fix a poor mileage issue. Yes, swapped O2's, ran codes, etc. My mileage started sliding after I had my heads swapped, but it was a gradual decline and may have started before the heads were done. Damn this issue! It seems like every other guy on this board has a similar problem! :damnit:

Here's a way to test for leaking injectors: Connect a rubber hose to the injector where the fuel rail would normally connect and apply compressed air to the rubber hose. I hook the whole thing up, apply compressed air to the injector and stick it in a paper cup of soapy water. If the injector leaks, it makes bubbles.

If you are going to pull the injectors to check them, you'll need new seals. Fuel injector seal kits with 2 O rings and a pintle cap (Borg-Warner P/N 274081) are available at Pep Boys auto parts. Cost is about $2.74 per kit. The pintle caps fit either injectors with a pin sticking out the injector end or 4 with more tiny holes in the injector end. The following are listed at the Borg-Warner site ( http://www.borg-warner.com ) as being resellers of Borg-Warner parts:

http://www.partsplus.com/ or http://www.autovalue.com/ or http://www.pepboys.com/ or http://www.federatedautoparts.com/

Most of the links above have store locators for find a store in your area.

 

[siege]

wouldn't a leaking injector cause the car to run rough? and if one were stuck open, could you just use a mechanics stethascope (or whatever they are) to listen to each one as its running? or would this not work?

no MAF here, but I'll stop at autozone and get some crap for my filter and TB and pick up a new PCV (forgot about that one)

 

[siege]

btw, anybody know if the PCV is different from 86-87? just got one for 86 and its different than whats on my setup...

 

[89MustangGX]

nope. your odometer works off your speedo cable, which in my situation, doesn't work at all. if your speedo reads faster than you are going, your actual mileage will be less than the odometer says, and vise versa. blah blah, that should help

Oops...let me try again. If your speedo is off or not working there is NO way to calculate your mileage. Any other way will be far inaccurate at best.

 

[MAC'n89Blckstng]

I just put new 02 sensors in my car, eliminated my surging and gave me insane gas mileage (well for a 5.0). My car is running so well now.

 

[siege]

Oops...let me try again. If your speedo is off or not working there is NO way to calculate your mileage. Any other way will be far inaccurate at best.

I already knew my mileage from before it broke. Also, I can still tell I'm getting bad gas mileage cause I can only go like a week on a tank...used to be 2-2 1/2 weeks...