Is this it or what?

[87ChevyR10]

So, I took a little trip to Ponca City in my R10 the other day. Drove about 80 miles and burned thru about half a tank of gas which means I averaged about 10 MPG or so. That's low for a TBI truck, IMO. Truck has stock sized tires, lid flip on air cleaner and desmogged with full headers. My average speed was 60 to 65 in between towns. There were some hills, but I didn't floor the pedal to climb them. Based on tach, I was hovering at 1800 to 2000 RPM's. I know the spark plugs are over due, but the engine isn't misfiring. Also, daytime temp was in upper 80's. I noticed when I drove home that night, I got better mpg.

Is what I am seeing to be expected or are there some gains I can get? Thanks!

 

[yevgenievich]

If 3/4 ton 4wd can do 12mpg on mud tires and loaded, you should be in 15-16mpg range. Unless you are drivibg 85mph.

 

[chengny]

So, I took a little trip to Ponca City in my R10 the other day. Drove about 80 miles and burned thru about half a tank of gas which means I averaged about 10 MPG or so. That's low for a TBI truck, IMO. Truck has stock sized tires, lid flip on air cleaner and desmogged with full headers. My average speed was 60 to 65 in between towns. There were some hills, but I didn't floor the pedal to climb them. Based on tach, I was hovering at 1800 to 2000 RPM's. I know the spark plugs are over due, but the engine isn't misfiring. Also, daytime temp was in upper 80's. I noticed when I drove home that night, I got better mpg.

Is what I am seeing to be expected or are there some gains I can get? Thanks!

From the EPA's website:


1987 Chevrolet R10 Pickup 2WD 8 cyl, 5.7 L, Automatic 4-spd
Regular Gasoline

You must be registered for see images attach

You must be registered for see images attach

MPG:14
combined
city/highway


City MPG:12

Highway MPG:17


7.1 gals/100 miles


It would appear that you are running a bit under the EPA's MPG rating.

But it is very likely that your apparent low mileage has more to do with the method you used to calculate it than it does with the truck's operation/performance.

If you really want to get an accurate picture of your fuel economy, you'll need to do more research.


You can't just take a short trip, estimate the miles driven and then - even worse - rely on the gas gauge to provide you with total amount of fuel consumed. There's more involved:

1. To do this right, you need to burn off nearly a whole tank of gas.

2. When you go to the gas station to start the test, fill the tank up to the very top - like you can't squeeze another drop in. Then write down the mileage as indicated on the odometer.

3. Drive around normally - until the tank is nearly empty.

4. Go back to the gas station and fill the empty tank. When topping it off, use the same method as when you filled it at the beginning. The important thing is to get the level in the tank just as high as the first time.

5. When you feel it is equal - check the volume dispensed (as shown on the gas pump) and make a note of the amount.

6. Get back in the truck and record the mileage on the odometer - before you drive away. (I'm not trying to be a wise guy, but I can't tell you how many times I do this entire test and then forget to record the mileage at the second fill up. Usually - maybe 20/30 miles later it dawns on me. But by then it's too late - and the entire test ruined because the data is invalid.)

7. Subtract the first odometer reading from the second one. Then take that number of miles and divide it by the total number of gallons it took to top off the second time.

The gas gauge readings on these trucks are notoriously inaccurate and should never be used to gauge fuel ecconomy.

After a fill up, you can drive around for 75 -80 miles and the gauge will still be way up near full. You start thinking that you are getting phenomenal mileage - and feel great. Then all of a sudden - almost right before your eyes - the gauge will start a violent drop down to halfway. It will hang there for a little while and then the second drop hits - you need to find a gas station like right now.

 

[87ChevyR10]

From the EPA's website:


1987 Chevrolet R10 Pickup 2WD 8 cyl, 5.7 L, Automatic 4-spd
Regular Gasoline

You must be registered for see images attach

You must be registered for see images attach

MPG:14
combined
city/highway


City MPG:12

Highway MPG:17


7.1 gals/100 miles


It would appear that you are running a bit under the EPA's MPG rating.

But it is very likely that your apparent low mileage has more to do with the method you used to calculate it than it does with the truck's operation/performance.

If you really want to get an accurate picture of your fuel economy, you'll need to do more research.


You can't just take a short trip, estimate the miles driven and then - even worse - rely on the gas gauge to provide you with total amount of fuel consumed. There's more involved:

1. To do this right, you need to burn off nearly a whole tank of gas.

2. When you go to the gas station to start the test, fill the tank up to the very top - like you can't squeeze another drop in. Then write down the mileage as indicated on the odometer.

3. Drive around normally - until the tank is nearly empty.

4. Go back to the gas station and fill the empty tank. When topping it off, use the same method as when you filled it at the beginning. The important thing is to get the level in the tank just as high as the first time.

5. When you feel it is equal - check the volume dispensed (as shown on the gas pump) and make a note of the amount.

6. Get back in the truck and record the mileage on the odometer - before you drive away. (I'm not trying to be a wise guy, but I can't tell you how many times I do this entire test and then forget to record the mileage at the second fill up. Usually - maybe 20/30 miles later it dawns on me. But by then it's too late - and the entire test ruined because the data is invalid.)

7. Subtract the first odometer reading from the second one. Then take that number of miles and divide it by the total number of gallons it took to top off the second time.

The gas gauge readings on these trucks are notoriously inaccurate and should never be used to gauge fuel ecconomy.

After a fill up, you can drive around for 75 -80 miles and the gauge will still be way up near full. You start thinking that you are getting phenomenal mileage - and feel great. Then all of a sudden - almost right before your eyes - the gauge will start a violent drop down to halfway. It will hang there for a little while and then the second drop hits - you need to find a gas station like right now.

Yeah, my Kawasaki Vulcan 900 does the same thing; so, I am familiar with this setup. However, since plugging the charcoal canister, the fuel tank holds pressure better and the needle is more stable. Before, the tank would pressurize then release and the needle would take a nasty fall.

Truck doesn't normally get topped off with gas. During the motorcycle riding season, it's my bad weather vehicle; so, I usually put just enough in it to get by for a trip or two to work. Although, these trips to Ponca City may get more frequent since I am seeing a woman from there (she's got Chevy blood, too). Plus, the bench seat has some uses not mentioned in the truck manual.

I'll try your method once the gas prices recover (2.49 per gallon in Kansas).

 

[bucket]

You can't just take a short trip, estimate the miles driven and then - even worse - rely on the gas gauge to provide you with total amount of fuel consumed. There's more involved

THIS!!!! You absolutely MUST do an actual calculation of miles per gallon and do it over a longer distance. I'd even suggest running through two tanks of fuel rather than just one.