Really bad mpg insight (1 Viewer)

[eaj71]

Hello

Trying to solve my Really bad mpg in my 1980 fj40 2f

Perhaps 6-8 mpg

It runs a trollhole carb. Desmogged and new manafre headers original distib

New plugs and wires

Idle is set low. Advance is at <5

It does diesel at shutdown. But besides this issue. It runs fabulous

Maybe something in the trollhole carb?

Or too rich? It is perhaps three turns out from the bottom. Can anyone explain if thinning it out is accomplished by tightening or loosening?

Any other advice is appreciated


Thanks
Eaj71

 

[White Stripe]

Have you documented your MPG or are u guessing? Need solid numbers to help you.

 

[JohnnyC]

Trollholes carbs like More advance ... 9-10 deg

 

[DSRTRDR]

my OEM carb (on a 2F) likes more advance as well

 

[workingdog]

I assume your measuring the mpg by how much gas you put in. Maybe it's not the engine, maybe there's a leak somewhere in the fuel system. I had a pinhole in my gas tank - lost a lot of gas that way.

 

[Landpimp]

Few thoughts

Bad egr, if you have one

Brake caliper or shoes sticking

Fan clutch locked up or locking to much

Timing.

 

[rkymtnflyfisher]

Too much weight in the right foot?

 

[rkymtnflyfisher]

6-8 mpg, where? Highway, city, dirt road, off road?

 

[Downey]

It's been my experience that 6-10 mpg Landcruiser tractor engines can be brought up to 13-14 mpg with the right products/tuning, but nothing beats the 14-20 mpg 5.3 Vortec V8's- - -just saying.

 

[Coastline]

Last trip to Az I got 15.6 mpg. Half highway, half not. 2F with DUI, Downey headers, zero vacuum leaks and currently about 11,000 on the odometer. Around town about 13.

 

[Jdc1]

Do you have bigger tires than stock? How are you measuring distance?

 

[Downey]

Last trip to Az I got 15.6 mpg. Half highway, half not. 2F with DUI, Downey headers, zero vacuum leaks and currently about 11,000 on the odometer. Around town about 13.

We consistently got 17 mpg with an F engine, 60061 vacuum advance dizzy, Downey header, and Holley 350 carburetor.

 

[eaj71]

i reset the timing to 10 deg btdc
lowered the idle a bit

i hope this helps.

FWIW
it is all in town driving but with not many stops
base size tires not 33" or something similar


but still seems low to me and less than what i had before a new head from SOR and a desmog and trollhole carb

thanks all for the further places to look

ill report back in a week

 

[Coastline]

We consistently got 17 mpg with an F engine, 60061 vacuum advance dizzy, Downey header, and Holley 350 carburetor.

What is the timing set at? And, tires? I'm running 33 inch BFG.

 

[Downey]

What is the timing set at? And, tires? I'm running 33 inch BFG.

Timing was about 7 degrees advanced, tires were 31X10:50's (back in the days when you got laughed at for trying to run 33's, well before rock crawling)

 

[lc69hunter]

The Holleys tend to like a little more advance also. A funny aside, I normally get 13-14 mpg, and after my last hunting trip I was consistently getting 8-10 mpg.

It took me two months to figure out that I had forgotten to air up my tires from 12 lbs after getting back on the roads. Check your air pressure.

BTW, just remembered, I bought that Holley from Jim, over at Downey.

 

[65swb45]

OP's new thread on carburetor troubles explains a lot. Primary is running at idle. There's your mileage killer.

 

[eaj71]

that seems to be the case..!

at least I hope.

 

[Mieser]

Stand alone wide band 02 gauges are getting pretty cheap now ($150-200) They take the guess work out of carb tuning.



Autometer even makes a nice needle one if the cheaper digital displays bother you.

Once you KNOW what the AFR is at different stages of operation you can start to adjust things for better mileage.
I would also suggest a vaccum gauge so you can track when certain circuits in the carb start to function, mainly the power valve type circuits for low vaccum high load. A lot of people end up running the vehicle very rich driving around on the PV circuit all the time.

Cheers

 

[eaj71]

65swb45. And all

It was a stuck open primary. The linkage was not returning home. Catching on a cotter pin

Mpg solved. Still cannot get it to die at idle with the solenoid unplugged. But it my be a bad solenoid. One has been ordered.

Thanks