mileage problems

[chariot_chaser]

OK, I know i didn't by this 86 wag for it's great mileage but I just drove 71 miles on the highway at around 67mph and it took 8.36 gallons. That's 8.5 miles to the gallon....something is wrong.
This was a colorado jeep, meaning on the vacuum diagram sticker in the engine compartment it state's it's been tuned for higher altitude. Now I recently went through and replaced the vac lines to the specs on the sticker; which are different from the diagram in the service manual. I know I have a blown power valve, but is a bad power valve enough to make that big a difference in mileage? Also, the timing was at 5 degrees btdc and I changed it to 12 degrees btdc (this confused me because I thought timing should be more advanced for higher altitude). When I originally got it I think I was getting 11 mpg. Oh yeah I'm in Iowa around 850 ft above sea level; high altitude for an octupus, but normal for fsj's. Any ideas?

[DjD]

I would say blown power valve. I know my power valve was full-on in the beginning because when we went to rebuild the carb. the vac. line was plugged with a screw and my NOz reading was almost zero. Was getting between 7.7 and 9.1 miles/gal. depending upon city/highway driving.

After carb. rebuild and new PV, now getting 10.7 to 15.2. The wider range of numbers of the after covers a longer period of time and isn't just the difference between city/highway but also what station pumps the gas and the auto shutoff of the pump. In New “Jorsey” we don't pump our own juice.

[chariot_chaser]

Yeah, I lived in Jersey for a few years, In a little town called turnersville or (sewell depending on who you asked). I always thought that it was wierd that you couldn't pump your own gas.

[reddog]

<BLOCKQUOTE>quote:</font><HR>Originally posted by chariot_chaser:
Yeah, I lived in Jersey for a few years, In a little town called turnersville or (sewell depending on who you asked). I always thought that it was wierd that you couldn't pump your own gas.<HR></BLOCKQUOTE>

It is the same in Oregon. I am so used to pumping my own that it is really weird to sit there while someone else does it.

See what happens after you rebuild your carb. I would bet that you get back to 11mpg ofr better.

Kerry

[ December 20, 2001: Message edited by: reddog ]

[okidoc]

Is it possible to blow the power valve on 2150 with a carb backfire?

[reddog]

<BLOCKQUOTE>quote:</font><HR>Originally posted by okidoc:
Is it possible to blow the power valve on 2150 with a carb backfire?<HR></BLOCKQUOTE>

From what I have heard yes it is but since the valve is attached via a rubber line it does not make sense to me - but then ALOT of things don't smile.gif

Kerry

[ December 20, 2001: Message edited by: reddog ]

[joe]

<BLOCKQUOTE>quote:</font><HR>Originally posted by okidoc:
Is it possible to blow the power valve on 2150 with a carb backfire?<HR></BLOCKQUOTE>
Yup...that's prolly the most common cause of blown power valves.

[Brown Bear]

If my brain is working properly (and that is not a given at this time of year), the carb backfire would make perfect since for a blown power valve. The backfire causes a tremendous amount of backpressure. Pushes the powervalve the wrong way, ripping the valve outter edges or ripping the center stem away from the disk. But I'm tired, so I might be wrong.