Turning up fuel to get better mileage?

[Lantec]

Does this idea sound absurd?

Basically, turning up fuel so I can rev lower, I shift around 1,600RPM now and it still has enough power to get me going in the next gear or even around town, I can put around around 1,300RPM and not to have to worry about lugging the engine.

Seemed even after turning up fuel, my fuel economy hasn't changed when I turned down the fuel. Only hitting about 1,000F on the EGT going up a huge hill in 3rd gear, a tad lower in fourth.

 

[Martin White]

I've noticed there is definitely an optimal point, and you either have to find it by trial and error or by taking it to a shop who can find it for you. But EGT's are your limiting factor, because if you turn up the fuel too far, you can get great power but horrifying EGT's, which is not good for your engine. I think if you go with a larger than stock exhaust, you can turn up fuel a bit more, but as Wayne likes to say, if you have more power, you use it, and it's likely your fuel economy would therefore end up either not changing much or getting worse.

 

[Tapage]

There are a limit in the turning up fuel in the power responce also .. and not only limited by EGT ..

There are spot ( the right one ) that you have enought fuel and great responce .. if you are really overfueling your engine not only produce over heating EGT also lacks of power ..

 

[Lantec]

I've noticed there is definitely an optimal point, and you either have to find it by trial and error or by taking it to a shop who can find it for you. But EGT's are your limiting factor, because if you turn up the fuel too far, you can get great power but horrifying EGT's, which is not good for your engine. I think if you go with a larger than stock exhaust, you can turn up fuel a bit more, but as Wayne likes to say, if you have more power, you use it, and it's likely your fuel economy would therefore end up either not changing much or getting worse.

Yeah definately. It's colder out now. I mark down with a sharpie on the fuel adjustment where I've had it last and experiment with where I turn it. Obviously, turning up fuel would have a limit before I start using too much fuel and going too high and smoke or something Lol.

I'll try tinkering with a bit more, basically, I've gone almost a 1/4 turn more than what I had before. I think I can go a bit higher without hitting over 1200F

 

[Mario]

Turned the fuel up on my rig 1/4 turn. No additional power (no that I can feel). Only black smoke. Turned it down an 1/8 turn, less black smoke (actually is grayish). Still no power.
What do you think? Should I cut it a little bit again?

 

[Lantec]

Turned the fuel up on my rig 1/4 turn. No additional power (no that I can feel). Only black smoke. Turned it down an 1/8 turn, less black smoke (actually is grayish). Still no power.
What do you think? Should I cut it a little bit again?

I think you've put it too much...

Make sure you're not going too high on your EGTs when you adjust ur fuel

 

[cody c]

a pyrometer would be good if your adjusting the fuel, if you dont already have one. uncombusted (overfueled) just means more heat.

 

[bigbrowndog]

I really do not understand why so many question adjusting the fuel pumps on these diesel motors unless you are fitting a turbo and increase it then. The fuel pumps are set at their optimum for performance combined with economy. If this is failing it is more than likely the injectors or the fuel pump needs servicing. The injectors should be done every 80 to 100.000ks and the pumps every 150/200,000ks. If the injector spray pattern is poor they can even grove the pistons and also bad injectors cause very poor combustion and loss of power.cheers

 

[Garry]

I recond my 2H about 20,000km ago including injectors, but I reckoned a 4 litre motor should have had more power than mine did .
So I started experimenting with the fuel screw. I adjusted it so that there was only visible black smoke under full throttle up hill. It only took about between 1/8 to 1/4 turn to increase power nicely. I have since fitted a pyro guage and it only gets up near the 1200 degree mark when going uphill on a hot day with a good load on behind.