Fuel Economy

[FTotts]

GEntlemen,

As I mentioned in another post my truck is getting close ot 100k on it and it is time for a valve adjustment. Along with this it should be noted the my fuel economy has gone to hell in a handbasket. I check it by hand on a regular basis and get around 20mpg. I am now down to about 15? I see no reason for this but have to wonder if my fuel pump is going galley west. I bought a replacement from Genos just in case but I guess I had in my mind that when it went the truck would not run. please share your thoughts about this problem.

Thanks

Fred T

 

[JWadford]

if i had 100k on a stock trouble free engine that started getting bad fuel mileage, i would perform a full tune up, like have the injectors gone through, replace all filters and fluids, test pressures like lift/rail fuel pressure under load and idle, along with the valve adjust when reinstalling the injectors then recheck performance and go from there, it is hard to make a guess without having a hands on the vehicle.

 

[rbattelle]

I find it extremely unlikely that a lift pump could cause a poor fuel economy issue, unless it's actually dumping fuel out onto the ground.

Check the underside of the truck to be sure you don't have a big fuel leak. If not, I would suggest an oil analysis to see whether you've got a leaky injector.

Ryan

 

[Bekim]

The lift pump either works or doesn't. I've never heard of one that is weak..... anyone... anyone..... Anyway, the big culprits i've seen are dirty air/fuel filters and injector problems. There isn't much else in our motors that would explain the symptoms you describe. Has the mileage gradually gone south, or is it sudden?
Mike
###

 

[FFL8N]

I had two lift pumps that didn't give enough fuel pressure... they would start to only put out about 5 or 6 psi at idle... that was in my 2000 truck with the VP44 though

 

[Ncostello]

The lift pump either works or doesn't. I've never heard of one that is weak..... anyone... anyone.....

If you've spent any time reading posts here... you'd know that your statement is not correct. Lift pumps are notorious for losing delivery pressure over time.

 

[JWadford]

If you've spent any time reading posts here... you'd know that your statement is not correct. Lift pumps are notorious for losing delivery pressure over time.

me too either loose pressure over time, or i had one that would work sometimes and sometimes quit when it wasnt supposed to so i had to whack it with a wrench a few times to get home,,,

 

[steved]

When did it start... colder weather will cause a drop in mileage (causes combustion to be less effecient).



Some owners report a mileage drop with winterized fuel, not sure its been put into play as of yet this winter?

 

[FTotts]

IT seems to have started about two months ago. Usually the overhead is pretty close to reality but it has been saying twenty mpg for a while and I did some simple math in my head and it dawned on me that something is wrong. I would like to o the injector maintenance myself but don't know how. Any help would be appreciated.

Thanks

Fred

 

[FTotts]

IN working on the truck, id checked for DTC's and got these two. 0602 and 0191. The list at the begining of this forum states that 0602 is a control moduleprogramming error/not programmed. That may be from my hypertech but I dont know. The other code I could use some help with. Anybody?

Thanks

Fred

 

[JWadford]

p0191 fuel rail pressure sensor circuit range performance

 

[FTotts]

So how should I interpret these two dtc's. Do I need to replace my fuel rail pressure sensor? Is there a diagnostic procedure that I should do first rather than just throwing parts at the problem. What do you all recomend?

Thanks

Fred T

 

[SShafranko]

Have you done the obvious and changed your fuel filter lately? (Drain the canister while your at it) First thing i would do is address the codes than get a fuel pressure gauge and check your pressure at idle, cruise and WOT. If you don't want gauges in your truck than hook up something temporary and check your pressure. Its a good inexpensive start.

 

[FTotts]

A fuel filter is on the to do list. The one that is in there only has about 3000 miles. I am usre it is ready for a change. I will keep you upated. I would like to know what the fuel rail pressure DTC really is telling me though.