swhite832

I recently took a trip from central Texas to the panhandle. On the way north I was pulling a 4runner and had a half the bed with wood. I averaged about 10mpg. On the way back I was running empty. I got about 12-13 mpg.

I utilized cruise wherever possible set at 70-73mph and 2100rpm. It ran about 550-650 egt's, and turbo boost varied. This truck has an A518 tranny and the rear end has 3.54 gears.

I understand that I am driving a brick but this gas mileage seems rediculous relative to what others are getting. The prior owner installed some different injectors. I have no idea of what they are. It does not smoke alot. It does smoke a little if I get into it, which I don't very often.

Since the turbo boost guage shows activity I assume the turbo is working(I cannot hear it). I guess there is a possibilty the torque converter is a piece but I would not know how to determine that. I am not sure if any of this stuff has any bearing on gas mileage but something is amiss. Any ideas?

Chrisreyn

I was getting about the same mileage with my 518A, 9-10 pulling the trailer and 13-14 empty..
I tryed adjusting the TPS and that helped a little.. since installing the potentiometer in place of the TPS and being able to control when OD engages, my mileage has gone up to about 14 towing, and around 18 empty..

Not saying yours is the same problems, but you might check the TPS and pay attention to if and when its shifting into OD, that seemed to help some in my case...

Micaiahfied

first of all gas mileage would be 0 Fuel mileage seems to be drastically different on different trucks. first of all take care of the obvious and change the fuel filter just to see. with my 9000# 5th wheel holding 80mph (2wd CC with stock auto) the losest i'd ever seen was 11mpg. The highest was 25mpg, that was unloaded traveling 70 with a cap on the bed (3.54 rear) see what the fuel filter does and report back, also make sure you don't have any leaks. I know those are basic things, but they are the easiest to overlook

ofcmarc

Check your tire pressure as well. Low tires = bad milage.

Ace

I haven't measured since the change, but I'm sure mileage has improved since turning out the starwheel a couple turns. Much easier to drive normally without dumping a ton of smoke (unburned fuel) during acceleration.

gomerpile

well even mine towing/driving it like i stole it, i got 15 at worst. and by best was 20, and i was traveling about 60-75,

Chrisreyn

Describe what you did please?

leper

For a lifted 4x4, your truck seems normal after reading alot here.

Ace

The starwheel adjusts tension on the AFC spring. Running the starwheel out (counterclockwise) increses spring tension, delaying AFC fuel delivery.

I suppose depending on what AFC spring you have, along with possibly custom fuel pin grinding might affect the results from this mod. I know it made a very big difference for me as I stated above. But then again I initially found the startwheel at only about one turn off the bottom to start with.

Like is often mentioned, all trucks/pumps are different.

swhite832

The only lift is additional leaf springs and the tires are stock.

It has not had a valve adjustmant in awhile. Could this significantly effect fuel mileage?

I am getting some additional smoke that I did not notice before. Is there any way to determine what kind, type, size injectors I have?

Micaiahfied

i don't agree that your mileage is average... even if it was a lifted 4x4... especially with 3.54 on the highway your numbers should be higher.
If you are just noticing some smoke you hadn't before take a good look for a boost leak. also did you change the fuel filter as i said earlier?

dpuckett

Valves being out will pull you down 1-4mpg, depending on how bad they are out of spec. Book spec is .010" and .020" for intake and exhaust, respectively. Most here go a hair tighter- 1-2 thousandths.

Fuel filter will cause bad MPGs, about the same as valve un-adjustment.

Your RPMs sound about the same as mine. I have a getrag with 3.54 gears. Your slightly higher OD ratio is lowered by the torque convertor, putting us at close to the same RPM. In my experience, cruise will LOWER your MPG, unless you are on totally flat ground. It pushes you too hard up the hills for optimal fuel economy. I let my pickup lose 5-8mph or so up hills, depending on length and grade. Keeps EGTs and consequently, fuel consumption, down.

Pump timing and injector condition will make a big difference. Has it always gotten that horrible mileage? Or is it just recently? Stock injectors are a 6 holers, 3550psi pop pressure. I got a set redone once, and gained 4mpg in a truck like yours with a manual.

Daniel

swhite832

When I first got it I was getting between 14-15 mpg.

I need to change the fuel filter and I need to check the valves. The injectors are aftermarket (235, according to previous owner. I do not know what tht means.) How do I determine what they are?

The truck runs really well. I would prefer less power if I could gain substantial MPG's

Thanks for all the input.

1-2-3

Driving habits is the easiest place to get better mileage. If anyone says anything about smoke on the takeoff, they should ever use the phrase "what's up with my mileage'

swhite832

I agree, so I keep my foot out of it...mileage is still poor. I have a sneakin' suspicion it is multiple issues. The only ones I cannot deal with are related to the injector system. I do not know what I have or how to manipulate it.