Chevy and GMC Duramax Diesel Forum banner
  • Hey Everyone! Vote for the Site Favourite ROTM winner for the year of 2021 HERE!
1 - 7 of 7 Posts

·
Registered
Joined
·
1 Posts
Discussion Starter · #1 ·
So I've got an 05 lly, recently it has been giving me some issues. The other day I was driving down the road and the rpms dropped and it lost power as if only half the fuel was getting to the engine. I put a new fuel filter on it thinking that could be the issue and it wasn't.

When it does this going down the road the rpm seems to do what it wants and the dash lights up saying "battery not charging". Before it does this going down the road the dash will go dim and light back up and the cruise will stop working.

It is totally random when it does this. It will randomly die while idling. Sometimes it will start to die then keep running like normal. When it dies the truck will start right back up with no problem.

I have just replaced both batteries thinking it would solve the issue because both were getting bad and it didn't. The alternator was tested and it said it was good but the issue never arose during the alternator test. Could it still be an alternator going bad? I'll take it out of the truck today and get it tested at an actual alternator shop.

I've also looked under the fuse block to make sure no mice have made a home since the truck stays in an old barn at night. Please give me some advice because I'm ready to pull my hair out. Any advice is much appreciated. Thanks.
 

·
Registered
Joined
·
315 Posts
Scan for codes (OBD II) and maybe there will be clues there. Many auto supply stores will scan it for free, or it's not a bad idea to just buy one. I always tell people I won't leave town without my Scangauge plugged in. It has saved me 2 or 3 times while on the road, as to what was wrong, and then to clear the codes so I could continue.
 
  • Like
Reactions: RachaelDeCoursey

·
Premium Member
Joined
·
3,676 Posts
The LLY injectors pull a lot of current when they fire so if anything is weak in the main DC power loop, it could cause issues. Have you checked to make sure all the grounds are making good connection? Might be a good place to start.
 

·
Registered
Joined
·
9 Posts
If it cuts out when pulling a hill or accelerating hard I would suspect air in the fuel or the rail overpressurebspring is weak that’s an easy fix but usually easy to tell it should be rather consistent and not at idle or low speed. In my 06 lly I installed a cheap clear fuel screen right before the fuel filter it was easy because their rubber lines. I was able to see air in the fuel and their shouldn’t be air in the fuel, I replaced a few fuel Orings in the lines but instead of going crazy I actually installed a fuel pump down near the fuel cooler which I also bypassed with a rubber line. The hose above the tank is fairly accessible that’s where I replaced the fuel oring (by the way gm doesn’t sell the orings only the lines which are crazy expensive). Anyways I still see a little air I don’t know where it’s coming from though I suspect the fuel pump which only 3-5 psi doesn’t fully keep up but it runs fine now and don’t have that issue. I would recommend installing a 10psi or more fuel pump theirs one with a clear screen which is nice to have you can add diesel 911 in a pinch. If it’s happening at idle or a hard start Issue I’d suspect fuel, your right with starting with the filter but the little primer pump could leak air too, it’s stupid they don’t have s lift pump it’s just smart to put one in!!
 

·
Registered
Joined
·
9 Posts
Also the the low rpm could cause the low charge I wouldn’t their first. Fuel in my opinion. I’d def start with a fuel pump one with a clear screen to see what’s in their Too I like my cute little too though near the fuel filter that’s after all of the potential air seeping points other than the filter housing and primer. Good luck
 

·
Registered
Joined
·
41 Posts
So I've got an 05 lly, recently it has been giving me some issues. The other day I was driving down the road and the rpms dropped and it lost power as if only half the fuel was getting to the engine. I put a new fuel filter on it thinking that could be the issue and it wasn't.

When it does this going down the road the rpm seems to do what it wants and the dash lights up saying "battery not charging". Before it does this going down the road the dash will go dim and light back up and the cruise will stop working.

It is totally random when it does this. It will randomly die while idling. Sometimes it will start to die then keep running like normal. When it dies the truck will start right back up with no problem.

I have just replaced both batteries thinking it would solve the issue because both were getting bad and it didn't. The alternator was tested and it said it was good but the issue never arose during the alternator test. Could it still be an alternator going bad? I'll take it out of the truck today and get it tested at an actual alternator shop.

I've also looked under the fuse block to make sure no mice have made a home since the truck stays in an old barn at night. Please give me some advice because I'm ready to pull my hair out. Any advice is much appreciated. Thanks.
This is called Limp mode. It is often caused by the ECM recognizing a problem and showing you an engine code on your display. Do you see the engine trouble light on? You should see it on every time you start the engine and when you have a problem. The first thing to do is get the code by reading it on an OBDII reader and looking up the problem. Without that you are going nowhere.
 

·
Registered
Joined
·
315 Posts
OP was a 1-post-wonder.
 
1 - 7 of 7 Posts
Top