Slow Speeds

[President Camacho]

The Humvee is known for its lightning fast top end. Peeling out, breaking speed records, etc.

I took my m1123 6.5 on the highway for the first time and barely achieved 50. It's a truck version circa 2004. It's been obviously sitting for a while... had only 71 miles when I got it. Am i doomed or will it/should it go faster?

 

[DatGuyC]

I'd say you have a problem if its a soft top truck. I have the 6.2 and can cruise at 55 pretty comfortably

 

[President Camacho]

I need to know where to start looking :/

 

[ryanruck]

My M998A1 will do 65 on the highway no problem (had it up to 69 once! ).

Do you have fresh fuel in it? If the diesel is stale, you'll definitely have reduced power. Also, probably couldn't hurt to run some Diesel Kleen through it. I add some every fill up. I double dosed my tank during the first several fill ups after getting her on the road and now just add the recommended amount.

 

[TOBASH]

I guess work from the bottom up....

Is your auto tranny shifting past second gear? Are fluids in tranny topped up?

Is your transfer case in high?

Are your brakes locking up?

Is your Ebrake locking up?

 

[infidel got me]

Would not hurt to change the fuel filter.... if you haven't already done so

 

[President Camacho]

I have put about a half tank of fresh fuel through her with an amount of diesel clean 1.5oz to the gallon.

This is a stupid question but how do I know if the hmmwv is shifting past second gear? In all the cars I've owned you could hear the car shifting but this thing doesn't make any noises like it's shifting. Do you guys here or feel your vehicle going from gear to gear? Mine just sounds like it's in one gear all the time. I don't 'feel' a shift and a drop in rpm and there's no tach to tell me it's shifted.

I will check my trans fluid.
Is my transfer case in high? I don't know - The lever is in the H position but I don't know if it's in fact doing what it's supposed to so that's a good idea to check.

My brakes shouldn't be locked up because it coasts really well.

I'll change the fuel filter.

 

[NDT]

If it's going 50 you can be sure it's in 3rd gear and high range.

 

[President Camacho]

Trans fluid is fine. I'd like to get the correct part number for the fuel filter. I have some parts manuals for the hmmwv but honestly because they have so many different models, they're a little confusing for me to read. I haven't taken the fuel filter out of this unit yet. Does anyone recommend any? I see Kascar sells one but maybe there's one I can get at an Auto Zone?

 

[Action]

autozone doesn't sell humvee only parts. all models have the same filter and water separator, AFAIK.

 

[Monkeyboyarmy]

Could it be stuck in second gear all of the time? Try shifting it manually from 1st to 3rd at higher rpm and feel for shifts.

 

[President Camacho]

ok

 

[Carrera911]

ok

Check the slack in the throttle cable. Make sure that at WOT it engages the kickdown switch at the end of the cable on the ip. When accelerating at wot it will wind out first to 28 mph, 2nd to 48 and shift to third. When you floor it from a stop it will shift pretty firm and give you a good jolt. At moderate acceleration, it is hard to feel it shift. I cruise mine at what the speedo calls 60 usually (not sure on that accuracy) with a 4dr 6.2l.


Sent from my iPhone using Tapatalk

 

[President Camacho]

Ok. I'm at work. Will have to do this all tomorrow. I'll look up the kickdown switch in the manual and find out what it is and where it's at. Mine is a 4 speed so no kickdown switch apparently?

 

[Retiredwarhorses]

There is no kick down switch on a 4L80e equipped truck on the injector pump, or any other Hmmwv for that matter, it's a fan disconnect switch. Perform the driveabilty tests in the Troubleshooting section of the TM's.
there is a throttle position sensor on the pump that works in conjunction with the crank position sensor.

 

[President Camacho]

I'm trying to find these driveability tests. Can you give me a key word so I can type it into the PDF find? If not, I'll just go through what I believe a check will be tomorrow and try to find the issue. I also don't have the troubleshooting manual for the 4 only 3 transmission. Also any hint as to which manual to look in for them would be a big help. Thanks.

 

[erasedhammer]

There is no kick down switch on a 4L80e equipped truck on the injector pump, or any other Hmmwv for that matter, it's a fan disconnect switch. Perform the driveabilty tests in the Troubleshooting section of the TM's.
there is a throttle position sensor on the pump that works in conjunction with the crank position sensor.[/UOTE]

24p-1 says the A0 and A1 trucks had the trans kick down. Shown below in the engine harness diagram.

 

[BLK HMMWV]

Doesn't say it's on the IP however at least not that I can see.

 

[gcbennet]

It's a military vehicle. Odometer #'s don't mean sh*t, especially since most of these vehicles have been driven like they were stolen and put to bed wet during their service. Not to mention sitting around compounds neglected and being cannibalized for months/years at a time. Drop and flush every fluid, replace all of the filters, replace every hose you can find, clean every electrical & ground connection you can find, grease all of the fittings, ensure everything is hooked-up and positioned IAW the TM's. I would also highly recommend pulling the injectors and have them all tested. My truck has less than 30k on the odom and all of my injectors failed and the IP needed to be rebuilt.

 

[President Camacho]

Did you make threads on what you did with the injectors and how you went about rebuilding the IP? Do you rebuild the injectors or do you have to replace them?