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Guest Message by DevFuse
 

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brat horible fuel milage


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40 replies to this topic

#1 disom93

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Posted 01 February 2014 - 11:00 AM

Im getting around 13-15 out of my brat ea71 with 205-65-15 mud tread recaps. Anyone have any idea whats causing it, ive heard the choke and i adjusted it i guess ill see

#2 rain_man_rich

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Posted 01 February 2014 - 11:18 AM

Man that thing must be running like hell.  Right?  If not I'd say you're leaking gas.



#3 disom93

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Posted 01 February 2014 - 11:28 AM

No sir it actually runs good and isnt leaking anywhere. I thought maybe the tire size untill i got to asking but i do alot of trap checking and just slow offroading thru fieldd so i know that hurts it but its gota get better then that? The choke wasnt getting volts so i rewired it maybe itll improve

#4 rain_man_rich

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Posted 01 February 2014 - 12:18 PM

I actually didn't expect that response.  Let me make a comparison.  I have a 5.7 liter in my chevy pickup which is more than three times the displacement your engine (and has bigger tires) and gets just a slightly lower gas mileage you are reporting.  Please note that all naturally aspirated gasoline engines utilize roughly the same air/fuel ratio. Given this, you seem to be running an incredibly rich fuel mixture.  So rich in fact that I would have expected it would run very poorly.  Of course if a choke plate was permanently in the closed position, this would richen the mixture but you should have noticed that after the car warmed up. Poor idling, stalling, idle control problems ect. would have been some of the symptoms.

 

I'd do a thorough check for vacuum leaks.  If there are leaks, they would have counter-acted the rich condition and let in air while idling.  


Edited by rain_man_rich, 01 February 2014 - 12:25 PM.


#5 rain_man_rich

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Posted 01 February 2014 - 12:24 PM

When was the last tune up? Plugs/wires/cap/rotor/air filter?  Also, you can pull the plugs for an inspection.



#6 hatchsub

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Posted 01 February 2014 - 02:15 PM

Are you sure your calculating it right?  WIth 15 inch tires, your tires are going to be turning much slower than they were with the stock 13 inchers.  This means that you will have a lower odometer reading than original.  So...lets say you really drove 350 miles between fill-ups.  Your odometer might only show 200 or 250.  So with that said if you have a GPS you might do well to set it for a known trip of maybe 200 miles roundtrip after you fill-up and then fill it up again and calculate it again.  

 

With that said if your mileage is really that bad then you will be running like absolute crap.  You should be seeing something like 25-29mpg possible better if you drive mostly highway.  Rain-man-rich is right though.  I get 10mpg with my 1991 dodge ram and even that is a bit lower than it should be.  Thats a 4000+ pound 318 v8 though.  Just to put it into perspective.  

 

All i can say is the ordinary stuff to start you off.  Check your timing.  Should be 8 degrees BTDC.  Advance it to 10 for a bit more oomph.  Tune up?  When was that last done.  Wheel bearings?  Are you needing some?  Thats overlooked but if you do a lot of offroading like you say you might have a few screwed up bearings and that will lower your mileage.  Just trying to get you started off.  



#7 rain_man_rich

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Posted 01 February 2014 - 03:14 PM

Expanding on what hatchsub said, your 15" tires are approximately 10% bigger "around" than the stock 13" tires.  You could add 10% to your odometer reading. So if you read 300 on your odo, you actually went 330.  Still, that only calculates out to be 14-17mpg.



#8 disom93

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Posted 01 February 2014 - 03:34 PM

Im going 160 miles and taking 11.5 gallons to fill up. And when warm the choke plate is not fully closed it is not open either. And it has new plugs, wires, filters exhaust is open with flow master, im kinda stumped as to what it could be

#9 disom93

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Posted 01 February 2014 - 03:36 PM

And the idle is kinda erratic sometimes, it will idle good and sometimes idle high randomly it has very rough recaps i think it hurting it most it got 26 on stock tires and hitachi

#10 RustyBrat

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Posted 01 February 2014 - 08:14 PM

hitachis do some weird stuff, just go weber if you can



#11 disom93

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Posted 01 February 2014 - 10:35 PM

Its got a weber 32-36 electric choke i thought i said that maybe not. I would just like to get some milage back its horrible. I appreciate the help

#12 silverback

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Posted 02 February 2014 - 12:10 AM

I use a vendor website for tire size comparisons. Go to Discount Tire. There are tabs at the top. Click on "Info Center". About halfway down the column on the left side is "Tire Calculator". Very handy. Enter your stock tire size and whatever you are running currently and you will see the hard data on speedometer/odometer error, difference in wheel rotations, etc..

No one has asked if you blow by everyone else in traffic when your speedometer indicates "60". Does the speedometer seem 'slow'?

The choke should be wide open shortly after start up. Has the gas mileage problem been long term or just when the unusual cold weather hit your area?

#13 disom93

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Posted 02 February 2014 - 12:19 AM

Well i lost the fuel milage when i swaped tires and i did the carb at the same time roughly. So i know the tires are alot of it but i still dont think its where it should be .

#14 Idasho

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Posted 02 February 2014 - 12:21 AM

My bet is on cold weather + short trips.

Especially if you are running non synthetic oil and gear oil.

 

 

Its pretty easy for me to see less than 16mpg in my GL if all Im doing is around town driving, which is 4-5 miles TOPS each trip.

 

Open road even in the winter I normally see about 25.  Summer it creeps right up to 30mpg.


Edited by Idasho, 02 February 2014 - 12:21 AM.


#15 disom93

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Posted 02 February 2014 - 12:24 AM

Ok thats what it is mostly right now the biggest trip is 10 miles back and forth and alot of times it isnt warmed up ny time.i get there and i shut it off again.

#16 Idasho

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Posted 02 February 2014 - 12:39 AM

10 miles it should def be up to temp.

 

Are you letting it fast idle at startup?  

 

Are you running the heater the entire time?  If you run the heater all the time, before it is up to temp, it will only take linger to get up to temp.  A LOT longer.



#17 Idasho

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Posted 02 February 2014 - 12:40 AM

Also, have you performed the proper weber lean-best tune?



#18 disom93

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Posted 02 February 2014 - 12:48 AM

No and usually at 10 miles it is but most of the drivinf its making rite now is 3-6 miles or so. And no i havent done the tune for the weber is that hard?

#19 Idasho

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Posted 02 February 2014 - 12:53 AM

Not hard at all.  Just takes patience

 

It is worth the time.  You will probably see better driveability, more power,  and better fuel mileage.

 

http://www.redlinewe..._lean_best_.htm



#20 rain_man_rich

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Posted 02 February 2014 - 01:44 AM

I use a vendor website for tire size comparisons. Go to Discount Tire. There are tabs at the top. Click on "Info Center". About halfway down the column on the left side is "Tire Calculator". Very handy. Enter your stock tire size and whatever you are running currently and you will see the hard data on speedometer/odometer error, difference in wheel rotations, etc..

No one has asked if you blow by everyone else in traffic when your speedometer indicates "60". Does the speedometer seem 'slow'?

The choke should be wide open shortly after start up. Has the gas mileage problem been long term or just when the unusual cold weather hit your area?

This is great! Sure beats doing the math.



#21 disom93

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Posted 02 February 2014 - 08:04 PM

Ok do you think its the tires + not cruising far causing the bad milage?

#22 disom93

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Posted 02 February 2014 - 08:26 PM

Can these adjuatments be made on the car?

#23 silverback

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Posted 02 February 2014 - 08:32 PM

Here is a link for a troubleshooting guide that may be helpful ( they do not sell the Weber Subaru kits but the guide is helpful )

 

http://www.webercarbsdirect.com/

 

There are tabs across the top of the site.  "Technical Information" is the tab.  Go to "Troubleshooting Guide" and print the PDF.



#24 disom93

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Posted 02 February 2014 - 08:41 PM

Do you think the coil could be bad making it get horrible fuel milage? Im stumped and some plastic piece in distributor is broke its black has holes in it its under the pickup and mounts for it its a black plastic piece

#25 Dinky26

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Posted 03 February 2014 - 12:17 AM

Do you think the coil could be bad making it get horrible fuel milage? Im stumped and some plastic piece in distributor is broke its black has holes in it its under the pickup and mounts for it its a black plastic piece


That surely won't improve your mileage in that state.




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