How to turn down the fuel to stock?

[kevin-m1008]

I have a question in that when I purchased my M1008 the previous owner had turned it up ~1/4 turn or so he remembers. The question I have is how do I move it back to what was original?
I do like the performance but the egt's climb way to fast and once I put a load on the truck I expect that I will have a bigger issue.

Thanks,
Kevin

 

[67_C-30]

I have a question in that when I purchased my M1008 the previous owner had turned it up ~1/4 turn or so he remembers. The question I have is how do I move it back to what was original?
I do like the performance but the egt's climb way to fast and once I put a load on the truck I expect that I will have a bigger issue.

Thanks,
Kevin

THIS - except turn the screw counter-clockwise.




You turn up the fuel by taking off the small cover on the drivers side of the injection pump. It is very small, and has 2 screws holding it on. You will need to remove the throttle cable and bracket to see the cover. Once this cover is off, a little bit of fuel will spill into the engine valley. What you are looking for is a small 5/32" Allen screw under this cover that appears through a small access hole. The screw rotates as the engine rotates so you will need to have a large ratchet or breaker bar on the crank pulley nut to rotate the engine while you look for the screw to appear in the access hole. You will need a small flashlight and mirror to see this screw. At first it seemed like there wasn't enough room, I swore I would have to remove the intake manifold. It helps to have a buddy turn the crank while you watch for the screw, but I did it my myself, it just took a lot longer. It does help to remove the throttle cable bracket and detach the throttle cable from the injection pump. You may also have to move the throttle linkage to get to the access cover and fuel screw.
Once the screw is in sight use a good quality 5/32" allen wrench to turn it. To increase fueling, turn the screw clockwise. It helps to turn it in small increments. 1/8 of a turn should be the max on a stock 6.2. Once the screw has been turned put it all back together and enjoy.

 

[kevin-m1008]

Thanks I will do it this weekend!

Also what should the egt's go up to when in the stock setting, when you have say a couple thousand pounds of wood in the back?

I'm more then willing to be slower if I can enable the motor to last longer.

Kevin

 

[67_C-30]

Thanks I will do it this weekend!

Also what should the egt's go up to when in the stock setting, when you have say a couple thousand pounds of wood in the back?

I'm more then willing to be slower if I can enable the motor to last longer.

Kevin

As long as you keep the EGT at 1000 or below, you will be fine. 1/4 is too much without a turbo, but you can usually get away with 1/8 of turn with stock 6.2.

 

[67_C-30]

BTW, the fuel plate is that your your looking for is circled in red. It is a little tricky to get to with intake, but it is doable.

 

[jimmy-90]

I was just wondering....How high do your EGT's get at 1/4 of a turn without a load if you sustain 50 or 55 mph and is the EGT probe threaded into the exhaust manifold?

 

[kevin-m1008]

Jimmy,
yes the EGT is installed in the exhaust manifold, currently when I drive from The Dalles to Portland I cruise at about 50-52mph per my GPS, the speedo says I'm doing 55. The temp stays around 400-450 at this speed. the highway is pretty flat with just a couple small hills of a few hundred feet in elevation gain.

If I just floor it from a stop by the time I'm doing ~45 my egt's are ~800 and climbing. This truck is pretty fast but at some point I will be using it as a truck and the temps just raise to fast when going up hills to be usable.

Kevin

 

[FormerNewMVGuy]

Well if there is no turbo to fry ,what are acceptable egt levels, i would think that in the exhaust manifold 1250 would be acceptable.

Your not going to have your foot to the floor nonstop, and if you arent trailering a heavy trailer, i dont see where you should be having a problem.

 

[YTS Deuce]

Don't know much about the 6.2 non turbo, but in the turbo Cummins / Duramax world, 1350 pre turbo EGT is the magic number you don't want to go over. Why are you guys saying 1000 is the limit on the 6.2? Are the pistons that much weaker that they won't handle the heat?

 

[Kohburn]

untill you have hit 1200degrees i wouldn't worry

 

[jimmy-90]

Jimmy,
yes the EGT is installed in the exhaust manifold, currently when I drive from The Dalles to Portland I cruise at about 50-52mph per my GPS, the speedo says I'm doing 55. The temp stays around 400-450 at this speed. the highway is pretty flat with just a couple small hills of a few hundred feet in elevation gain.

If I just floor it from a stop by the time I'm doing ~45 my egt's are ~800 and climbing. This truck is pretty fast but at some point I will be using it as a truck and the temps just raise to fast when going up hills to be usable.

Kevin

Hey Kevin-m1008 one thing you might not be expecting when you go to de-tune your injection pump is that the allen screw in there will be pretty hard to turn. Almost to the point that it feels like something is wrong with it but don't worry it is supposed to be hard to turn. LOL and for a couple minutes I thought you were driving your M1008 from Dallas Texas to Portland Oregon from time to time and was thinking WOW that must be a heck of a road trip in an old cucv. I didn't realize there was an area in OR. called The Dallas

 

[kevin-m1008]

The Dalles, Or. Claim to fame is its dam on the Columbia river other then that we are a wide spot in the road about 70 miles east of Portland.

Driving from Texas to Oregon in this truck would be tiresome and long. But I will say this my M1008 drives like a car compared to my M715.

Thanks for the heads up on how hard it is turn, I hate breaking stuff!

After I'm done it will be interesting if my fuel economy changes? I currently get ~14mpg cruising at 50-52 to and from Portland.

 

[67_C-30]

Don't know much about the 6.2 non turbo, but in the turbo Cummins / Duramax world, 1350 pre turbo EGT is the magic number you don't want to go over. Why are you guys saying 1000 is the limit on the 6.2? Are the pistons that much weaker that they won't handle the heat?

Well if there is no turbo to fry ,what are acceptable egt levels, i would think that in the exhaust manifold 1250 would be acceptable.

Your not going to have your foot to the floor nonstop, and if you arent trailering a heavy trailer, i dont see where you should be having a problem.

The 6.2 and the Cummins are 2 totally different animals. The biggest diifference is that the 6.2's compression ratio is 21.5 : 1 and the Cummins is 17.5 : 1 - 18 : 1, but the 6.2 is also an indirect injection design (vs direct on the Cummins) and the 6.2 has uncoated, cast pistons vs forged in the Cummins (and other HD diesels, The IDI design creates more heat, and if the you keep EGT's much over 1000 degrees, you simply cannot control the water temperature. This is the reason marine 6.2's and 6.5's can be turned much more than auto apllications. The 6.2 has a bigger radiator than the Cummins/D-Max/Powerstroke and still struggles to keep the engine cool, even in stock form, under heavy loads. The 6.2 in stock form in capable of around 200 - 210HP and 400 - 420 ft lb TQ which is very adequate. You can push a little more, but that's about the "safe" limit. Even at the "safe" limit, you can grenade one by beating on it. ****, you can grenade a stock one fairly easy by beating on it.

The 6.2 was designed as light duty diesel, with fuel economy in mind. Detroit's original design featured a beefier block, forged crank and pistons, and would have actually been a pretty good foundation for a lot more power. However, when bean counters at GM got through wittling down the costs, the result is what we have. In fact, the 1982 "red" block has a higher nickel content, and are stronger and MUCH less prone to cracking than anything '83 - up.

The newest version of the 6.5 being produced now by AMG is really how the 6.2 should have been built all along. Its all forged, has a much beefier block, has an integral stud girdle, and is rated at 250HP and 550 ft lb TQ. I'd love to buy of them for my M1009, drop the CR to 19 : 1 and install a Holset HX35 or ATT turbo, and a 4911 pump. You can achieve a RELIABLE 300+ HP - 600+TQ out of those.

 

[67_C-30]

Hey Kevin-m1008 one thing you might not be expecting when you go to de-tune your injection pump is that the allen screw in there will be pretty hard to turn. Almost to the point that it feels like something is wrong with it but don't worry it is supposed to be hard to turn.

Good call. They are pretty tough to turn, especially when coming in from the side.