Terrible gas mileage - only 175 miles on full tank

punchy · Post by **punchy** » Fri Aug 24, 2007 8:19 pm

I have an 86 Tercel 4wd wagon with 250k miles, purchased last May. The car needed a bunch of work when I bought it, so I had the following services done last June:

timing belt
TVSV valve (these are very hard to find - what an ordeal)
water pump
air filter
oil change
tune up/plugs/wires
new battery
new tires

After the repairs, the car was driven across the US, about 2,000 miles, and is now sitting most of the time, used for short trips 1-2 times a week. It runs well, but when the car is in stop-go traffic and gets hot, it diesels a bit when turned off. It also smokes a bit (sometimes white smoke, sometimes black), on start-up, going up hills, and when I punch the gas pedal. It's not burning oil and there are no leaks under the car.

On average, I'm getting about 175 miles on a full 13.5 gal tank. That's horrible. The car went in for an oil change yesterday and the mechanic noticed fuel residue/smell in the exhaust area and suggested an engine diagnosis for $90 to find out why it's using so much fuel.

Can anyone suggest some things to try before getting into expensive engine repairs? Obviously we should get a new fuel filter, though I think the problem is beyond that. Anyone know what's causing this based on what I described?

I'll check back regularly - thanks for any help.

brianp · Post by **brianp** » Fri Aug 24, 2007 9:41 pm

It sounds like either carburetor or timing issues to me... You might try giving it a tune up. Look in the pdf manual for tips there. I'll let others be more specific on suggestions.

neonsport · Post by **neonsport** » Fri Aug 24, 2007 10:40 pm

brianp wrote:It sounds like either carburetor or timing issues to me... You might try giving it a tune up. Look in the pdf manual for tips there. I'll let others be more specific on suggestions.

I'd guess both carburetor and timing, but start with the timing for cost issues. With the smoking under acceleration and climbing hills, your carburetor almost certainly needs a rebuild.

BTW, is your Tercel a stick or an automatic?

takza · Post by **takza** » Sat Aug 25, 2007 3:12 am

I do this stuff first:

* check and fix all vacuum tubing leaks...espec around the charcoal canister

* check vac tube routing

* tighten carb and manifold bolts

* text your dist for vac advance

* take a look at the float level front of carb

keith · Post by **keith** » Sat Aug 25, 2007 6:46 am

* take a look at the float level front of carb

What takza is talking about is that there is a little round glass window on the front of your carburetor. The fuel level should be half way up this glass, if its higher, then unmetered gas will spill over into the engine.

You probably will have to clean the window first, and you can only see it with the air filter off.

Another problem with all cars of this age is sticking weights in the distributer as well as ruptured diaphragm's in the vacuum advance.

Another source of poor mileage is a seal diaphragm in the fuel pump. That can pump fuel into your oil. If you can smell gas on your dipstick, then its time for a new one.

All the other suggestions here are also valid so you have your work cut out for you, good luck.

punchy · Post by **punchy** » Sat Aug 25, 2007 1:19 pm

My 86 is stick shift.

Thank you all for the tips. I'm not a mechanic and have limited tools, but I'll try doing the things I'm capable of - the rest I'll probably have to take into the shop to be checked.

BTW, I bought a Chilton Tercel 84-94 manual found at a used bookstore - are these manuals thorough enough to help me try to do some of these repairs myself?

brianp · Post by **brianp** » Sat Aug 25, 2007 2:07 pm

It is nice, but we do have a PDF of the original Toyota Tercel shop manual for the 85 model.

It is pretty thorough.

http://tercel4wd.com/1985_Manual.pdf

It is 65 MB.