85 c10 5.0 starts then dies won't hold idle
 

Hey yall, Im working on a coop truck that hasn't had much maintenance in a few years. Hard starts got it to the point where it would no longer start without running down the battery.

I charged the battery, replaced some of the vacuum lines and put in a new cap and rotor plus cleaned up the carb without removing it. Truck started but died right away. Let it run for a while with throttle input and it still dies as if it wasn't even designed to idle. It's as if you killed the ignition while in the power band but it still had spark, it just dies...

Not sure if I caused this by fussing with it or if it was getting to this point already since Im not the only driver. I am cautious btw...

It seems the PO had disconnected a few vacuum lines and there is a strange junction of "t's" that don't make sense behind the carb according to pics I have seen online. I think the egr bleed solenoid is disconnected but in the diagram there seems to be only 1 vac line exiting the back of the carb but in reality there are two at least. I would like to correct the vac system and repair and diaphragms or whatever that have been neglected, I think the gas mileage will return...

I haven't seen any year specific pictures online of the vac system that I can use to compare Dusty's setup and the diagram to.

Thanks for any help you can give, I read up on the posts and feedback on this board and was impressed, GMC's not in my knowledge but if you find yourself in need at swedespeed or r3vlimited come find me.

Marcos

Re: 85 c10 5.0 starts then dies won't hold idle
 

Is the gas fresh?
Is the fuel pump pumping well?
Are the messed up vacuum lines at least capped, so as not to create a massive vacuum leak?

Personally, I'd pull the carb and at least blow out all the jets and whatnot. (carb cleaner, not compressed air)

3 things it needs to run, fuel, air, and spark. Once all these things are present, then work on the when. Sounds like air and spark are present already.

Lots of smart folks here, I'm sure more will chime in.
And Welcome!

Re: 85 c10 5.0 starts then dies won't hold idle
 

WElcome to the forum!!
Best bet is take us some pics of your truck especially some of the motor with and without the air cleaner on from a few sides. We can help you better that way. And besides WE LIKE PICS!!!
Here's a link for an 85 c10 vacuum hose routing.
http://forum.73-87chevytrucks.com/sm...?topic=24370.0

Re: 85 c10 5.0 starts then dies won't hold idle
 

put some gas in a cup (from the line)does it look/smell ok?
check for dirt in the gas filters
(one jerry can of bad gas works wonders)
stock would be @ the line in on the carb
1" wrench for the big one,watch for the nylon seal
check the bigger vac lines too,i had a huge crack in mine from the carb base to the canister,
connection to tranny?
oily lines loosen up ,and i found wiggling the hoses off the carb sometimes the "tube" loosens and pulls out a touch,I gently tap then in

Re: 85 c10 5.0 starts then dies won't hold idle
 

Thanks guys, I will look into these things and get some pics tomorrow.