9mpg? Somthing is not right.

[fyfer]

I figured out my mileage the other day and came up with 9.5mpg! I know that I did the math right but for the skeptics out there here is a rough estimate:

I filled up my tank and drove about 140km, I then filled up with 27L. 140 divided by 27 gives me 5km per litter. Times 4 is 20km per gallon, or about 10MPG!

I'm running 31" tires but the GPS says my speed-o is right on! (its not factory)
My tailpipe is black, but I figure I would have to be running pretty rich to get milage that bad.

Any suggestions? Does anybody know where the mixture screw is on the canadian carb?

[CodyJ]

Its a carb setup? I am not familiar but is it an 8v or 16v? Probably 8v. Does it run rough or idle right? Pick up good? I only know how to do the mpg in US GAL.

Take you're odemeter when its reset, fill up tank and mark the amount of gallons the tank was filled with from Empty. Say 8.4 us gallons usually.

I can then drive until it gets Empty again and then I usually go about 250miles on the odemeter and I do 250 divided by 8.4 and thats 29mpg US.

Goodluck.

[fyfer]

It is a carbed 1.3L 8v, and I need to keep my foot on the gas during warm up, but once warm it runs good, I was thinking the air/fuel mix screw, but wouldn't it run crummy all the time? No linkage is sticky cause I hosed 'er good with cleaner.

[squid]

I am going to assume this is similar to the 86,87,88 USA model samurai. these use a feedback carb., the o2 sensor in the exhaust send a rich-lean signal to the ecm which control a mixture soleniod in carb. the o2 signal is voltage. When the exhaust is lean the voltage drops to less than 0.4 volts and when rich is greater than 0.4 volts with a max reading of around 1 volt for a very rich signal.
the o2 sensor is best checked with a lab scope but you can use a volt meter. with everything connected you need to back probe the o2 connector (USA model use one wire o2 sensor) to get the voltage signal betweem the o2 and ecm. with engine warmed up you should varying voltage signal above and below 0.4 volts. if you disconnect a vacuum line you should see the voltage bias to the less than 0.4 readings and if you choke the carb the voltage should bias to greater than 0.4 volts.
a shorted o2 sensor will give a 0 volt signal falsely telling the ecm the exhaust is lean, the ecm will then send a signal to carb to add fuel and richen mixture. the engine may not run badly right away but the fuel milage will drop.
this is a good place to start and of course you need to check the basics like plugs , wires , timing , loose vacuum line , ect . let me know what you find and if this doesn't fix problem, I will help you check the rest of the system.
SQUID

[fyfer]

Wow! Thanks! The only thing is I dont have an 02 sensor. The engine is an 88 but the sammy is an 85. I would assume that the carb is an 85 and it must be the canadian model because my guages are in km/h. I have no ECM, to old. Is there a way to tell what year the carb is?

[squid]

Ignition timing is the single, most critical adjustment for a gasoline engine. Assuming the engine is in good mechanical condition, there are no vacuum leaks, and the fuel mixture is correct, then the ignition timing can affect the net power yield from the fuel. Improper timing can significantly change a vehicle's mpg.
there are four types of timing
1. static
2 . vacuum advance
3 . machanical advance
4. valve timing

we will start with valve timing and not being familar with canadian engine we will just assume again. On the front cover of engine there might be an access hole to view cam timing mark or you may have to remove cover. the crankshaft is set on #1 cylinder top dead center and the mark on cam gear mark should allign with a mark on head. you probably should look at a manual for this. a picture is worth a thousand words. the belt can stretch and jump a gear tooth and if there are more than 50,000 miles it is a good idea to change it anyway.

next is static timing, this the one most everyone is familar with. the engine need to be warned up and running at slow idle. the distributor vacuum line is disconnected and pluged. timing light is attached to #1 spark plug wire and the light is directed in a hole in bell housing. the distributor is twisted untill the correct marks line up.
mechanical advance is checked by using same timing light procedure above . engine speed is increased to 2500 rpm and and a reading is taken. the differance between the static and this reading is your mechanical advance. also observe the timing change as you increase rpm it should advance smoothly.
last is vacuum advance. for this check I use a hand held vacuum pump. checking that the diaphram holds vacuum and also using the timing light that the timing advances smoothly and returns to static timing when vacuum is released. the vacuum advance is a common falure item.
SQUID

[hotrodsami]

That sounds like a vacuum leak. Look for loose, old, or cracked hoses. also see if the carb i still bolted down all the way. If you have a vacuum tester plug it in you should get close to a -28 reading at an idle speed.

[Phils]

What squid said X2.

But if you don't have a hand-held vacuum pump, just use a length of vacuum line, attach it to the distributor vacuum advance and suck on the other end. If you can keep sucking the advance is bad and not only doesn't advance the timing but is in itself a vacuum leak.

That may not solve all your problems but I'll guess yours is bad if it is the original.

Phil