Diesel Place banner

How to bleed a fuel system

15K views 26 replies 11 participants last post by  Diaric 
#1 ·
I tried to prime my fuel system but there is no pressure, how do I bleed the system?
 
#2 ·
how are you trying to do it to have no pressure?
 
#3 ·
I usually take the fuel line off as close as I can get to the IP and use a push pull hand pump . I have one for doing oil burners.
 
#4 ·
i just crank the hell out of the engine, its gotta start someday right? :p:
 
#10 ·
You have a priming bulb? Could you post a pic of that? I've NEVER seen any sort of primer on a 6.2.......
 
#6 ·
yea that was meant as a joke. i wonder why GM didnt have enough sence to use a pump like whats found on tractors or the 12 valve cummins. with that little pumping arm on the lift pump so you can prime the filter and injection pump if something like this happens. might be hard to reach though .....
 
#7 ·
this is why i installed an electric pump, i just turn the key till its primed
 
#8 ·
bah. you guys and your damn electric pumps. lol.
 
#9 ·
its easier than the cummins prime lever that you need a stick to use
 
#12 ·
If you can get a pic that would be great :thumb: Like I said I have NEVER seen any sort of primer on a 6.2......
 
#14 ·
sounds like this primer bulb was put in by a PO. i put one put on my snomobile so i could pump it 3 times then it would fire right up on the first pull(1973 roll-o flex, hell of a sled let me tell you :D). but i dont know how well a primer bulb would take that 6 psi from the lift pump. and the heat of the engine since its soft rubber.
 
#15 ·
I have a question about trying to get the air out. Don't you basically have to run all the air through the system by cranking the engine, because where can the air go? I guess you could open one of the injector lines but that seems to be a lot of effort if you have only changed the filter.

I am asking because I just changed my square filter for a new spin on type and I sprung for a primer pump add-on. It seemed like a good idea, everyone likes buying new parts right, but I am thinking where is the air going to go unless I can bleed it out?
 
#16 ·
same place the fuel goes, runs rough and misses till all the air is gone.
 
#19 ·
yea like diaric said, just coughs burps and farts and rocks around untill it gets running right. yesterday i was bored and lostened the injector line for the front cylinder on the driverside. holy damn did that make it run rough and cough and rock around.
 
#20 ·
so if ya don't get all the air out of the system, then will it just run rough but then work itself out? and could having air in the system actually cause the engine to die while running down the road, especially on inclines/declines, or does that sound more like an IP issue? any easy way to tell without just replacing the IP?
 
#21 ·
yes, buts thats usuall not a getting all the air out issue. thats more of an air leak and its sucking more in. inclines declines, sounds like the pickup tube leaking
 
#22 ·
thanks bud, but I have no idea which question you were answering "yes" to.....
"yes" the air will work itself out of the system?
or
"yes" not having all the air out will cause it to die?

I am thinking ya meant the latter, but not certain....??

thanks for the help bud, much appreciated!
 
#23 ·
yes causing engine to die. ip issue probablt not. lift pump could be failing though. and will it run rough with air in and clear itself out.. yes
 
#25 ·
It could be sucking air. Fuel line are known to rot along the chassis.
 
#26 ·
Yes that's what I hoping it is. I'm still using the old in cab tank, and bet its the section of rubber line under the truck right before it goes up into the cab.
 
#27 ·
ya, rubber lines or something is screwed in the tank pickup
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top