Is it possible to turn your injection pump up to high on the 6.2?I had a pump redone and they said they would turn it up the 1/4 turn that the turbo company recomended.I let it like this for a year and desided to turn it up another 1/4 turn not knowing if they had did it or not.I lost about 3 mpg and gained 2 pounds of boost but doesn't seem to have much more power than before.I was only gettin around 13 before I turned it up so now I'am at 10mpg.
I wish I could get the 18 mpg that oters say they are getting on this site is there something wrong with my truck or does the tubo give more power and less mpg?Is this normal mpg on a turbo 6.2?Everything seems ok a little extra black smoke is noticed I have a kn filter with a cold air intake that I made up.

1988 1 ton creww cab 4x4 with 410 gears.

Your help will be apreciated:
Superman

Your mileage seems low. What size are your tires? Overdrive tranny or direct? 4.10 with 235-85-16 tires should yield about 15-16 mpg on a healthy 6.2 with a turbo. That is of course if you are not flooring it all the time. What kind of boost numbers are you showing? Have you adjusted your timing? I would start by advancing your timing about 1/16 inch towards the driver side and then test your mileage. What are your max pre turbo egt's? I used to run a 6.2 with the injection pump wide open and it ran great and still turned in respectable mileage. The trick is that with more fuel, the throttle doesn't have to be moved as far and the lighter the throttle the more advance you get on timing. Full throttle equals max retarding of timing. Max full throttle pre turbo egt's shouldn't exceed 1150 F and boost should be limited to around 12 psi max.

D.Camilleri:
I"am running 33 inch tires with a turbo 400 trans.Ok I was showing about 10 when I installed and then I turned up the pump a 1/8 turn and got about 12-13 depending on load.
I tried to turn up the timming and it sounded like it was detonating at just one lines width so I turned it back.Last night I turned the pump back down a 1/4 turn so it should be at stock spot( they turned it up prior to when I got it)Now it seems really slow and the idle was high and didn't want to come down even with the screw I think I put the lid on wrong.I"am going to take it back of tonight and check it out.
I also thought that since I had the pump turned up that maybe that is why I couldn,t bump any timing into it I don't know what do you think?
What do you mean turned all the way up did you take the top off and tighten the allen screw that turns up the pump all the way?
My egt run about 900- 1000 around were I live but towing heavy up Fancy gap in N.C or Virgina it was getting up to 1200 so I had to limit it .
Let me know what you think just want to get the most out of this truck until I can get a knew one which doesn't look like it will be to soon.
I also just bought a 2 car hauler and want to be able to make it back from N.C. with 2 cars on the trailor.

Superman

One test I like to do is to depress the advance lever with the engine idling, it is the lever on the passenger side of the injection pump. In normal operation the throttle has a ramp that depresses the lever, as the lever is depressed, it retards the timing. Depress the lever fully with the engine idling, it should make the engine stumble, does it? When you say the engine sounded like it was detonating with the pump advanced, do you mean the diesel rattle was louder? If the engine is quiet with little diesel rattle, the timing is too far retarded. Retarded timing will also cause high egt's. I used to run my injection pump with the allen screw bottomed out and backed off 1/8 turn:eek: I have always found that power and economy is better with just the right amount of fuel. If you don't have enough, then your foot is in the throttly all of the time, thus retarding the timing. Let me know what you find.:grd:

what do you mean by "turning up" the injection pump? Do you mean advancing the timing?
Reason i ask is i just advanced the timing on my IP today just a tiny bit and when i started it up, it seemed to idle a bit faster than before but i am not sure if this is related.
thanks
Paul

D. if the engine doesnt stumble, are you suggesting the timing isnt advanced far enough? I have been trying to find out just how to determine if I have my timing advanced far enough.

What all is involved in turning the pump up? how far can I/should I go with a non-turbo setup? I would like to get the most out of my truck. (sure cant wait to get some real gears and OD in this thing....)

Paul : We are talking about the allen screw underneath the top solenoid cover on the I.P. not the timming.There is a scew that you turn clockwise for more fuel and counterclockwise for less.Ats recomended turning mine up alittle with the addition of there turbo system.

D.Camilleri:

I did turn the pump back up about an 1/8 and it is alot better also finished my cold air intake seems good and now the bost is up around 12 psi.

The timming thing it has the normal diesel rattle but when I turned it up it didn't sound wright and the sound didn't seem to be a louder rattle.Hard to explain but didn't sound wright.When I replace the injectors the diesel rattle became louder and it didn't sound like that.I will try the lever you mentioned tomorrow and let you know what I find out.Thanks for your help.

Superman

Basically depressing the lever gives an indication if the advance piston is working propperly. No change in the way the engine runs is bad, stumbling indicates timing is about right, if the lever is depressed and the engine stumbles and then you increase the timing and depress the lever and the engine no longer stumbles at all the timing is too far advanced.

Thanks D. that helps me alot!! sure wish you had told me a couple months ago when I asked ;)

Now about turning the pump up? Or should we start another thread for that?

Better to go with a new thread, makes it easier later when using search engine for 1 question & answer string per heading, it's also easier for me to make a FAQ out of it.

D:

I tried pushing the rod today and I did hear a difference but it wasn't alot a little stumble maybe.I was also wondering why I can't turn the idle down with the adjustment screw it still idles a little high no matter how far I turn the screw out.It isn;t hitting the fast idle adjuster either.



Superman

I noticed the same thing about the rod. a noticable difference in idle speed, but I wouldnt call it a stumble per say. I will say that I did tweak my pump advanced some more yestarday, and I am almost happy with the way it runs. I still need to turn it up though. and I worry that I might be too advanced just based off my position in reference to the line.

You guys might want to try and get tdg involved since he rebuilds pumps, but for me, when mileage is down and advance piston doesn't make a lot of change, could be time to repair pump. A timing meter would be the best bet so you could see exactly how much change is going on.:eek: Good base line test would be to depress lever with timing marks lined up and you should notice substantial stumble. Be carefull running timing too far advanced, could be a bit hard on head gaskets.:cool2:

Is it possible to turn your injection pump up to high on the 6.2?
I was only gettin around 13 before I turned it up so now I'am at 10mpg.

1988 1 ton creww cab 4x4 with 410 gears.
It's certainly possible to turn the fuel up too high on any engine.

Do you know what model the pump is? A 6.5 pump calibrated for turbocharger will get better mileage/performance than a 6.2 pump at the same max fuel delivery will, best bet, buy a 4911 pump.

1ton, crew cab, 4x4 and 4.10 gears, probably a TH400 tranny too?

Thats all the ingredients you need for poor mileage alright ;)

700R4 and 3.42 gears will make a new truck out of her, mileage wise.

TDG, I am dealing with a military blazer, I assume that it is the stock pump for what they had. as far as mileage, I plan on removing the 3.08 gears, and the TH400 and swapping htem for 4.10's and a 700r4 some day....

I am going to work on it someday, and take it one small turn at a time.

3.08 gears? on a military blazer? surely 3.42 is whats in there now?

either way, I'd leave it and go with the 700R4.

they were all 3.08's and I suspect this still is...

the pickups were all 4.56's

both with turbo 400's

I thought it was Dana44's with 3.42s in the blazers and Dana60/70 with 4.10s in the trucks, don't know for sure on that.

I wish... blazers are 10 bolt 3.08 front/rear, with a govlock in the rear, and the trucks are dana 60 front, corp 14 FF rear with d-locker, and 4.56....

the trucks really SCREAM at highway speed... ;)

Geez, yeah I'll bet they do ;)

I worked on a couple HMMWV's, only saw and talked to the motor pool guys about the trucks/CUCV's.

I really wish I had 3.42's or 3.73s... they would be best I think for my situation with the 700r4... but I own 3/4 4.10 axles with a d-locker in the rear... so I am using them. going to take the 4.10's out of the front axle, put them on my gov-lock carrier from the current rear axle, and put them in the current front...

can we say front and rear locker!!!! :ro) :ro) :ro) :ro)

):h