Ok, so I am assuming the bronco has a 33 gallon tank on it. I haven't found any other options for tank capacity on the 87's. I filled it up until it wouldn't take anymore gas. It had some in it already and I put in over 25 gallons.I wrote the mileage down when I filled it up. He drove it until he ran it out and the truck died in the street.

So if the capacity is 33 gallons, how much is it possible to actually get in it ? 31 , 32?? Then when it ran out how much would you assume was left in the tank? 1 or 2 gallons??

These are the unknowns I a trying to estimate in order to get a semi accurate mpg number.

All help and opinions are appreciated!

 

The catalog shows it to be a 32 gallon tank - see below. But, the only way to calculate mileage is to fill it up and divide by the miles. Do that for several tanks in a row and you will get a good average. But to figure it by how much is left in the tank will only get a very rough approximation.

Having said that, I always get more out of a tank than the manufacturer specified. So I would bet Kris ran at least 32 gallons out, and probably more.

 

If it was 32 then that makes the mileage 6.9.

The previous owner thought he was only getting around 7 with the HO 351W.

It may get a little better as the motor tightens up, but it has over 1000 on it now. So I don't think it will get much better.

 

I was thinking about leaning the carb up some. I have a set of metering rods that will lean it up 4%. The exhaust still smells rich even though the carb is tuned in pretty well. There is no hesitation or stutter. I am seeing some low idle issues, but it could be the plugs fouling also.

 

Leaning it up with rods may help. Give it a try. And fouled plugs don't help at all.

 

That is a very difficult way to figure out your fuel mileage. Do what Gary said and just fill the tank up two or three times, you don't have to run it empty. If you want it even more accurate, use the same pump at the same station, and always put it in the same notch(slowest would probably be more accurate). That will help it fill the tank up to the same level each time to increase accuracy.

 

The guys above are right. for calculating fuel economy, you don't need to know the size of the tank, and you don't need to worry about doing fills from empty. just fill ton the top each time, and over the course of a few tanks, any variations in "fullness" will cancel each other out. you will have a very accurate number after four or five fills.

Assuming of course, that your odometer is accurate, but that's another issue completely. . . . .

 

The gas gauge doesn't work at the time. I haven't figured out yet if it's problems are tied to the other electrical issues the Bronco is having or not. It could be the sending unit itself. I plan to work on the electrical issues this weekend and get closer to the solution.

I let him run it out just to get an idea how far he can get on how much gas until the gauge gets back on line. I wrote the mileage down when I filled it up just so I could get in the ballpark.

 

Have you hooked the choke up? If it isn't coming off it will cause bad mileage.

 

Yeah it's hooked up, but just powered off of the hot leg on the coil. It has variable voltage, but not less than about 10 1/2 I assume. I need to do some relay work in the near future though.