Where Did I Go Wrong?

Joined
Sep 12, 2005
Messages
19
Location
Amarillo, TX
I just replaced the intake/exhaust manifold gasket on my truck and it starts easier, idles smoother and runs better but my gas mileage has gone way down. I don't know my exact fuel mileage, but before I was driving 225 miles on a tank of gas and now I'm doing good to drive 150. I had the carb and vacuum lines off, could I have crossed vacuum lines or leaks that are causing this? I haven't had time to double check this. Any input would be appreciated. :confused:
 
Joined
Aug 17, 2005
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Location
t town, wa
you know i am having the EXACT THING happen. i just noticed it as i changed it the other day. but i know all my vaccuum lines are correct. used the wiring diagram and took photos.
 
Joined
May 19, 2005
Messages
686
What was your mpg before? 225 miles into 18 gal is 12.5mpg which is normal. 150 in 18 gal is only 8, so thats quite a difference. If you're talking about a FULL tank of gas the difference is less.

If the vacuum lines are good (check everything really well) start from scratch and do a timing check and all the other normal procedures. Chances are you'll find the culprit along the way.

Is there a significant change in idle speed?

Do you have WAY more power?

I've been getting at least 12mpg with a properly tuned 2F.
Toad
 
Joined
Sep 12, 2005
Messages
19
Location
Amarillo, TX
Yeah thats on a full tank Idle is about the same but much smoother power is only slightly better I'll have to check vacuum and timing and hopefully figure this out.
 
Joined
Aug 17, 2005
Messages
1,264
Location
t town, wa
i h have exactly the same milage as el guapo now. 225 before and about 150 now
only i suspect that the culprit could be the carb. had to do some leaning out. hopefully it helps. ill let you know what happens with mine
 

RredFJ40

 
 
Joined
Nov 1, 2003
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Location
Klamath Basin
I don't want to get into a mileage discussion but wow, 12 mpg properly tuned? I regularly get 17 on my desmogged 82 with close to 250K miles!


Toadhopper said:
What was your mpg before? 225 miles into 18 gal is 12.5mpg which is normal. 150 in 18 gal is only 8, so thats quite a difference. If you're talking about a FULL tank of gas the difference is less.

If the vacuum lines are good (check everything really well) start from scratch and do a timing check and all the other normal procedures. Chances are you'll find the culprit along the way.

Is there a significant change in idle speed?

Do you have WAY more power?

I've been getting at least 12mpg with a properly tuned 2F.
Toad
 
Joined
Sep 12, 2005
Messages
19
Location
Amarillo, TX
I've always heard that 12 mpg is about average. Anyway right now 12 would be great. Going to replace all vac hoses, most of mine are original and have never been replaced, and check timing when I get time.
 
Joined
Jan 26, 2005
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in the garage
El Guapo said:
I've always heard that 12 mpg is about average. Anyway right now 12 would be great. Going to replace all vac hoses, most of mine are original and have never been replaced, and check timing when I get time.

if they are all original, then you may or prolly cracked one or two when removing the line and manifolds

let us know what you come up with

btw i get 10-12 mpg runnin 4.88 and 35"tread
maybe i should adjust my valves someday :doh:
 
Joined
May 19, 2005
Messages
686
RredFJ40 said:
I don't want to get into a mileage discussion but wow, 12 mpg properly tuned? I regularly get 17 on my desmogged 82 with close to 250K miles!
17MPG! Are you sure you're adjusting for the size of those 33s?
Most folks seem to get about 12-15 depending on their driving habits. I just finished adjusting the valves and setting the timing, so I'll check on the next fill up. I do mostly "around town" driving but 17, sheesh thats REALLY good.
Toad
 
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