My '87 gets absolutely terrible mileage. I've tried everything, i've even used a very light foot for as long as i could stand it. What is killing my mileage so much? I'll put it this way, a short (20 mile) free trip doing 70 used approximately an 1/8th of a tank. By my estimation that'* NINE MILES PER GALLON!!! On the HIGHWAY. What is going on here? Keep in mind my lockup doesn't work so i'm running about 2500 RPM at 70, but there'* no way that the lockup not working makes my mileage go from the 25-30 that most people claim to 8-12 that i have been getting. I think my PCV valve may need to be changed, can that do it? No i don't have a plugged cat. in case that would do it (in fact i have none at all). All the plugs are good, and the wires SEEM to be in good condition. The O2 sensor is also new. The EGR works fine although i get a code for it, i've tried cleaning it (moves freely) and swapping soleniods, no difference. Please help!

calculate your gas mileage, then we'll talk.

btw, gas gauges can be off you know.

I'm just throwing this out ther, fuel filter or clogged/inoperable fuel injectors?

Yeah, don't go just by the gauge. Fill her up, record the mileage, drive at least 100 miles, fill back up, record the mileage, do some math. The more miles you drive, the more accurate your calculations will be. Anything will be better than "I drove for 30 minutes and my gauge moved 1/8 of an inch" though.

Also, a fuel filter can't cause bad mileage. You can't be using too much fuel if it can't get through the clogged filter. A bad injector, maybe... but lets make sure that you're actually getting bad mileage before guessing the cause of it.

That is a good point, but with gas the way it is now a days and my VERY limited income it becomes very difficult to fill her up the entire way. But i'll just have to pinch pennies for a while and try to get it. But it seems to me that before there was a time i had filled it up the entire way and only gotten 250-350 miles on one tank, which is closer to 20 MPG'* i think but still not acceptable in my book. Maybe a bottle of fuel injector cleaner will help also? Or 2?

it could. have you checked your air filter? i hear those can mess with mileage too.

Yea my air filter is fine, i've also gutted my airbox. I'll have to save up the money to fill this fat bastard up! Lol

The other thing to remember, if anyone else has noticed, that when you fill it up, you get more mileage from full to half, then from half to empty.

It is just as easy to top it up from 3/4 to full than from empty to 1/4 tank. Plus it is better to keep it full, since that is what cools your fuel pump.

wouldnt that cause different symptoms?