Hmmwv won't go on drive when in H but it will go on LOW

[Lui1152]

I am having issues with my hmmwv.
When in H and drive it has no power. As if there is not enough compression for it to go. I accelerate and nothing happens.

When it is in LOW and drive, it goes.
I already checked the return lines. I blew air in them and they are fine. I also changed the fuel filter.

The hmmwv revs fine when in park.

Any ideas?

It was driving fine before it sat for 1 week and half.

Thanks

 

[Action]

What do fuel return lines have to do with the transfer case? I bet your truck will move in HL and drive, too. If so, something is broken in the driveline. Probably part of a halfshaft.

 

[Mogman]

You need to be clear about what you are doing, are you talking about the transmission or transfer case when you are talking about high and low???
You look restively new here so to start were all the fluids and filters replaced to start with?? and when you say no go do you mean it will not move at all or just does not have enough power to move well in high range, someone else may chime in here if you have a 4 speed could it be in limp mode??
I just looked it up, if in limp mode it will only be in second gear, would be very sluggish for sure

 

[Lui1152]

What do fuel return lines have to do with the transfer case? I bet your truck will move in HL and drive, too. If so, something is broken in the driveline. Probably part of a halfshaft.

Thank you for your reply.

I checked the fuel lines because it was seating for almost 2 weeks in 12 degrees. The original thought was that the fuel gelled up. But unfortunately for me, it was not that easy.

Could you please elaborate more in your answer.
It make sense but I have no idea where to start checking.

 

[Mogman]

If it was a half shaft it would move in HL and L

 

[Lui1152]

You need to be clear about what you are doing, are you talking about the transmission or transfer case when you are talking about high and low???
You look relitivly new here so to start were all the fluids and filters replaced to start with?? and when you say no go do you mean it will not move at all or just does not have enough power to move well in high range, someone else may chime in here if you have a 4 speed could it be in limp mode??

Thank you for your reply.

Yep, I am really new to all of this. I am a little mechanically inclined but not experienced enough with hmmwv.

When I put the transfer case in H and the transmission in overdrive, there is no enough power. It is sluggish....
When I put the transfer case in LOW and transmission in overdrive. It drives with better power but still really sluggish.

 

[Mogman]

If in limp mode it will move OK in low range but the transmission will not shift

 

[Mogman]

You are going to have to get a handle on whether it is a drive train issue or lack of power, unfortunately "not enough compression to go" does not sound like you are fully understanding how the truck works. it is a diesel, it literally runs on compression, if it did not have enough compression it would ether not run or run poorly with allot of smoke.

 

[Action]

Does the truck move at all with the transfer case in H? What happens with it in HL?
Limp mode will drive like normal until it wants to go into 3rd gear.

 

[Lui1152]

Does the truck move at all with the transfer case in H? What happens with it in HL?
Limp mode will drive like normal until it wants to go into 3rd gear.

Yes, it moves when in H but sluggish.
When in HL, same as when in H. It moves sluggish.

 

[Mogman]

Does the truck move at all with the transfer case in H? What happens with it in HL?
Limp mode will drive like normal until it wants to go into 3rd gear.

Not exactly true, in limp mode it will be stuck in 2nd gear only, it would feel somewhat sluggish from a standing start, so it would not act "normal" until time to shift to 3rd.

 

[Lui1152]

You are going to have to get a handle on whether it is a drive train issue or lack of power, unfortunately "not enough compression to go" does not sound like you are fully understanding how the truck works. it is a diesel, it literally runs on compression, if it did not have enough compression it would ether not run or run poorly with allot of smoke.

Runs poorly with a lot of smoke.
When in park, it revs fine.

 

[Mogman]

Yes, it moves when in H but sluggish.
When in HL, same as when in H. It moves sluggish.

That sounds like ether a power issue or your brakes are really dragging, or EB is on

 

[Mogman]

Runs poorly with a lot of smoke.
When in park, it revs fine.

Should have led with that!

 

[Mogman]

You say revs fine when in park, are you saying it runs poorly and smokes only when in drive?

 

[Lui1152]

Should have led with that!

I appreciate the responses. I am here to learn.

 

[Maxjeep1]

Mine wouldn’t shift into overdrive and was sluggish and I thought I was having transmission issues and then I realized that I left the emergency brake on when I left the store. Stupid lol

 

[Lui1152]

You say revs fine when in park, are you saying it runs poorly and smokes only when in drive?

Really hard to start in cold.
When it finally starts, it revs fine.
All of these with lots of smoke.

When in drive, sluggish and more smoke.

 

[Mogman]

And a week ago all was fine?

 

[Lui1152]

And a week ago all was fine?

Yes
It was driving fine.
It was cold (12 degree). So the initial thought was fuel gelling.