HORRIBLE Mpg!

[Korey5640]

Ok, I have a '89 Ranger XLT with about 150,000 miles on it. It runs rich and blows black smoke and was getting 4 MPG....thats right 4! I took it to a mechanic friend and he said that it wasn't a sensor and that it was the motor was going and to put a heavier oil in(50W/20). Well, I did so and that helped the smoke and it runs a little better, yet still smokes somewhat and still gets the same 4 mpg.

Any ideas? It is costing me around $20 a day to drive to school and back! I only paid $500 for the truck...HELP! I can't afford it and might have to toss the Ranger.

[ct91rs]

Putting in the heavier oil will help it burn less oil, as the higher viscosity will allow less oil to travel into the combustion chambers. That same thick oil will also make it harder for your engine to run (increased resistence on internal parts) thus decreasing horsepower and mpg.

If you paid $500, unless the body is in great shape, (I bet there's a decent amount of rust on the bottom of the doors and around the rear wheel wells.) or you just really love the truck, I'd cut your losses and get rid of it. Sounds like major engine problems that would only be solved by a rebuild or a different engine.

Sorry, but I don't see an easy fix.

[Psychopete]

Usually when it's burning oil the smoke is blueish/white. Water is usually white. And running rich is black.

How did he come to the conclusion that the motor was going? Have your mechanic friend leak down or compression test the engine. This way you'll know for sure if the engine is going or not. If it runs with no lower end knock and the piston rings are still good, I'd be tempted to fix it. Even if it needed new heads, compared to other cars, this Ranger isn't bad at all.

Have your mechanic friend check the fuel pressure. Should be 40psi. You could easily have a ruptured fuel pressure regulator. If it's ruptured, you will find fuel in the vacuum line to the upper intake plenum. It's on top of the fuel rail, drivers side, it's round with fuel lines going to it. The vacuum line is on the other side, near the fire wall. It could still be bad if you don't find any fuel, it's a good idea to check the fuel pressure regardless.

Is the check engine light on? There's quite a few sensors that contribute to the air fuel mixture. I cannot tell you exactly what is wrong, it would be like shooting at ducks blind folded. But scanning the codes checks over the electrical circuits for faults and voltages that are out of range. This will only give you hint of what's wrong, you'll need to figure out why there's a fault in the circuit. The sensor itself could be still good.

Also check the wiring to the o2 sensor.

Scan the codes.
http://www.troublecodes.net/Ford/

Pete

[Korey5640]

The Check Engine Light is not on, never has come on either.

[Psychopete]

Originally Posted by Korey5640

The Check Engine Light is not on, never has come on either.

I converted my 88 Ranger to mass air flow and I used a used Mustang MAF. It just went bad and my truck wouldn't shift into OD anymore and my CEL didn't come on. Scanned the codes, MAF was the first code. Replaced it with a 3.8L MAF, adjusted my IST Air Adjuster, and along I went. This is why I suggest to scan the codes.

It's simple. Take a look at that link I gave you and look at 2 bottom diagrams that show just a single wire from the top right connection to the square plug. All you need to do is put a wire inbetween there and turn the ignition on run. The check engine light will blink out the codes.

The computer also has no idea what the fuel pressure regulator is doing, due to the fact that it's vacuum operated. It has nothing to do with electronics. If the FPR diaphram is ruptured, it will literally leak fuel right into the upper intake plenum.

Pete

[Korey5640]

Ok, I am looking at my ranger and can't find the vacuum line to the upper intake plenum to check for fuel in it. Also, I have recently discovered that my oil has a lot of gas in it, enough to cause the oil level to increase visible. Also, last time I changed the oil(about a week ago) it was about a 35/65 of gas/oil. Also, it leaks some oil(a very small amount), so the only way I can explain the increase in fluids would be having more fuel put into the oil mixture.

Please help me find this since it sounds most like my problem. Thanks, any pictures/diagrams would help greatly.

[ct91rs]

cracked intake, bad piston rings???

[fastus edwardus]

I'd say it's almost certainly a fuel delivery problem, fuel pressure, or a bad sensor or fuel system component, maybe even the main engine management module/computer/thingy...def. have the engine checked before you write it off, it's most likely not an engine problem. The excess fuel being put out will wash past the rings and dilute the oil. This will continue until you get the fuel problem fixed. Good luck...

[Psychopete]

Originally Posted by fastus edwardus

I'd say it's almost certainly a fuel delivery problem, fuel pressure, or a bad sensor or fuel system component, maybe even the main engine management module/computer/thingy...def. have the engine checked before you write it off, it's most likely not an engine problem. The excess fuel being put out will wash past the rings and dilute the oil. This will continue until you get the fuel problem fixed. Good luck...

+1

It's a 2.9 right? If it's a 2.3L, I don't know anything about those 4 bangers. Except for the fact that they last a long time. It really sounds like the fuel pressure regulator is literally gushing fuel into the intake. Get the fuel pressure checked to make sure it's a fuel delivery problem, then replace the faulty parts. I cannot tell you it's that part for certain, only for the fact that I haven't seen the problem myself. It could be a problem with the computer controlling the injectors as well, but it's usually better to start simple. A fuel pressure gauge is about 40 bucks. See if you can rent one or something if you cannot purchase one. The fuel pressure should give you the clue you need to determine what's wrong. Should be around 40 PSI.

Pete