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New Guy from Central Oregon needs help with 6.5

mauler0311

mauler0311

mauler0311
Messages
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Location
Redmond OR
First i just want to say that this site has been a life saver for getting my 98 gmc 6.5 running. You helped me bring her back from the dead. I just need a little more help to get her to perfect.

The truck starts fine and runs great until she warms up. Then the truck will idle bad not really rough and not stalling but just dips down and then back up and repeat. Here is the kicker I have found out that when i turn on the lights it will idle fine if i turn off the lights back to idling erratically again. When the truck is really warmed up, say when i get off the highway even with the lights on the truck will revert to idling erratically, unless i hold the breaks really hard, (on this truck their is a electric brake something or other, i don't know exactly) that will run and cause the engine to idle smooth again.

So i be leave that an electric draw on the engine causes it till idle correctly. Other then that i am stumped. Any help would be a life saver.
 
Welcome to The Truck Stop! :welcome5:

It would help alot for you to fill out your signature but I'd say go over all of the grounds on the truck for starters. Have you remote mounted the PMD yet?
 
Sorry i didn't know what a signature was, this is my first post on a blog.

I be leave the grounds are all good, however i will check again. And the PMD i dont know what it is so i will find that out and check on that. thank you btfarm for pointing me in a direction.

And thank you for the warm welcome.
 
Go to Forum actions tab above then 'edit profile' then you will see a page full of all the things you can put in there. And hey, everybody is new once...:D
 
Just checking to see if signature is working.
And the PMD was remote located with a heat sink.
Still have not checked all grounds yet should have time tonight.
 
Hi mauler0311

I believe the ground point at the right rear of the engines cylinderhead, close to the AT dipstick is a critical point, if this has bad connection or none i have experienced a "no start"
And the ground at the top of the IP.

Børge
 
Welcome to this awesome site!

I also believe this to be a ground problem. Never just "look" at the ground and think it's in good shape. Remove the bolt/washer and clean underneath it. You'd be surprised what's underneath a clean looking ground!
 
Well i spent some time Sunday taking off and inspecting all the grounds on my truck, cleaning and then putting them back together.
The two from the batteries to the engine and from batteries to body also the one ground wire from the back of the engine to the frame and fire wall and wiring harness.
Did i get them all?
also this did not change the idle once warmed up.
So where do i go now
 
I found out that if i run the lights and the fans for the heater/ac the truck idles fine i wonder if it might be the ground on the PMD well i think its the PMD its on the back of the fuel distributed i be leave it has a ground back their.
I'll have to check that, maybe tonight.
 
I don't have a trans dipstick its a manual and i didn't see any around that area except the back of the engine to the frame and then to the firewall but i cleaned that one. However i did not check a around the trans ill try and check that also.
 
mauler0311 said:
I don't have a trans dipstick its a manual and i didn't see any around that area except the back of the engine to the frame and then to the firewall but i cleaned that one. However i did not check a around the trans ill try and check that also.
Click to expand...

To check the manual transmission in these trucks there is a fill plug on the passenger side. Remove the plug and the fluid should be up to the top. If it is not it is low.IMG_0629.jpg

Here is a picture of mine with the plug removed along with the PTO cover.
 
I believe there are some grounds under the dash, one by the ecm, for the ecm. It may not hurt to pull the ecm and disconnect and reconnect the plugs.

Other than that I'm at a loss.
 
thanks for the help dieselcash but i was talking about ground wires around my trans the trans is fine i just checked the fluid last month.
 
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