Turned Fuel Up in M925A2 (M939A2)

[PapaPumpSD]

I finally was able to turn the fuel up in the 1990 M925A2. I ended up taking both the 14mm and 10mm nuts completely off since I didn't have a way to adjust them separately with the tools I had. I am having a special 14mm socket made that will allow the 10mm socket to reach through the center of it. You can remove the nuts w/o a special tool but you'll need a DEEP WELL 14mm socket!

Special thanks to nevrenufhp for his patience and technical assistance!

A video is found below....it's not exciting, rather, the purpose is to show how much smoke there is (or isn't!). I was expecting a lot more smoke. In fact, prior to turning up the fuel, we had already turned up the fuel at idle (a different adjustment on the fuel pump) ~3/4 turn out which made the rig roll serious coal when you got on it in 1st gear. But after I turned up the main fuel, the smoke really mellowed out.

I will say that the bottom part of 1st is still a dog but apparently you can remedy this to some degree by turning up the idle fuel. I'll toy with that later.

The truck does run faster. I like it. I'll be able to keep up with traffic better and hopefully not bog it down going through these Colorado mountains. I have added a boost & EGT (exhaust gas temperature) combo gauge added. If you plan on turning up your fuel, I highly recommend that you install an EGT gauge. Otherwise you risk burning up your motor.

On a side note, I'm powder coating some parts to give it some eye candy. We just finished the indicator light cluster (flat black w/white letters) that holds the indicator lights found in front of the steering wheel. Looks great and it is very durable. Now on to other parts!

https://youtu.be/j2tDqLrGcyA

 

[Rmtaunton]

I just rolled a 10mm , 1/4 " socket on bench grinder till it would fit in the 14mm, only took a couple minutes

 

[PapaPumpSD]

I just rolled a 10mm , 1/4 " socket on bench grinder till it would fit in the 14mm, only took a couple minutes

This is a great option.....if you have the tools to do so. I hired a machine shop to do it since I'm not mechanically inclined.

 

[PapaPumpSD]

Update: I took the truck out today to check the EGTs. I brought it up a steep hill here Colorado and the engine temp & EGTs were fine. EGT didn't get past 1,050 F. The only issue I did see was the trans oil high was almost 275 F which is above the 220 F max normal operating temp (Max operating temp is 300 F). I think the trans oil temp was elevated due to the truck banging through the gears fast and w/more force.

Any recommendations on how to get that trans oil temp down?

 

[MtnSnow]

Actually getting a transmission to shift firmly decreases the fluid temp. When you have slippage is another cause for increased fluid temps. What was your coolant temps like as the coolant cools & or heats the transmission fluid via it's so called cooler.

 

[Monkeyboyarmy]

I was told that the only thing that heats up the oil would be the oil pump and torque converter. GM transmissions were designed to turn off the oil cooler lines when the torque converter lock-up because that was the major heat source. If the lock-up would not work or slip, it would cause elevated temperatures.

 

[74M35A2]

I don't think there is anything one could do with an empty truck to cause a healthy trans to run hot. Usually trailer towing will heat a trans. I'd go dollars to donuts that the temp sender or gauge is just not accurate. Our trans coolers are huge. On an empty truck, the trans temp should almost always be at or below engine coolant temp. Mine is in my 925A2.

 

[PapaPumpSD]

I don't think there is anything one could do with an empty truck to cause a healthy trans to run hot. Usually trailer towing will heat a trans. I'd go dollars to donuts that the temp sender or gauge is just not accurate. Our trans coolers are huge. On an empty truck, the trans temp should almost always be at or below engine coolant temp. Mine is in my 925A2.

Before I turned the fuel up my trans operating temp would be around the engine op. temp (~190-195F). Then after I turned up the fuel the trans oil temp nearly hits 275F. I can check to see if the trans cooler is working properly and I'll check fluid levels also.

Thanks for everyone's thoughts!

 

[adamsoffroadperformance]

I have my fuel cranked as far as it will go. I can thump on it all I want and the trans stays about 150. Drug my new to me M373A4 home wed from Aberdeen Proving Grounds and even pulling the 2 mountains trans temp never got over 150 degrees it's a 3.5 hr trip one way. The truck wanted to pull the mountain in high gear but the egt's would crank up so I dropped a gear and held it about 3/4 pedal which kept the egt's around 1275 degrees and I pulled the mountain at about 50mph. I'm gonna say you have a messed up sensor or gauge or a wire rubbing through somewhere.

 

[PapaPumpSD]

Great info, thanks for sharing. I'll have to dig into this some more. Glad to hear the tranny shouldn't have a problem running the increase in power.

 

[PapaPumpSD]

Actually getting a transmission to shift firmly decreases the fluid temp. When you have slippage is another cause for increased fluid temps. What was your coolant temps like as the coolant cools & or heats the transmission fluid via it's so called cooler.

The engine temp was ~190F.

 

[TCD]

On a side note, I'm powder coating some parts to give it some eye candy. We just finished the indicator light cluster (flat black w/white letters) that holds the indicator lights found in front of the steering wheel. Looks great and it is very durable. Now on to other parts!

How did you re-letter the light cluster?

It looks Great!

View attachment 617696

Tom

 

[PapaPumpSD]

On a side note, I'm powder coating some parts to give it some eye candy. We just finished the indicator light cluster (flat black w/white letters) that holds the indicator lights found in front of the steering wheel. Looks great and it is very durable. Now on to other parts!

How did you re-letter the light cluster?

It looks Great!

View attachment 617696

Tom

Thanks Tom! We've been working on techniques to apply the powder to fine areas such as alphanumerics. You can try applying it in powder form and gently "pack" it into the letters/numbers then remove the excess with a gentle adhesive tape or something similar. It's tedious and requires patience. But I think it's worth it as it gives the part a more professional look. No cutting corners here. The toughest part are the prep phases. Removing the CARC, rust, surface imperfections, media blasting, etc. We plan on doing other parts on the truck (interior and exterior).