purging air from fuel line

[Flagman]

Hi all more knowledgabe than I: In several circumstances there is talk of bleeding air from lines such as when a fuel filter is replaced, when the fuel pressure guage is installed, etc. My question is: How exacty is this done? I've heard that you turn the key three times. Is that with the clutch depressed to make the engine turn over or just with the key and no engine turn over? In the instructions for hooking up a fuel line to a guage isoator, the manual talkes about running the lift pump until the fuel flows good without air. How do you do this while you are in your truck turning the key, or cranking the engine? Hope the question makes sense. It will be obvious to some Im sure. thanks Mark

[volkswagon]

I don't have too much knowledge on this but I do have a wee bit of experience. You just turn the key to the start position long enough for the starter to engage (but don't start the engine) then release it but don't turn it off. This makes the fuel pump stay running so now you can monitor the flow out of your line to see when the air bubbles stop or whatever you are trying to do. Just turn the key off when you want the pump to stop. I have an automatic so I don't know about stepping on the clutch but I'd think you'd have to to get the starter to turn over.

[Flagman]

thank you for your response. My problem is that as soon as I turn the key, the engine starts, no delay at al?

[SASQCH]

Hi all more knowledgabe than I: In several circumstances there is talk of bleeding air from lines such as when a fuel filter is replaced, when the fuel pressure guage is installed, etc. My question is: How exacty is this done? I've heard that you turn the key three times. Is that with the clutch depressed to make the engine turn over or just with the key and no engine turn over? In the instructions for hooking up a fuel line to a guage isoator, the manual talkes about running the lift pump until the fuel flows good without air. How do you do this while you are in your truck turning the key, or cranking the engine? Hope the question makes sense. It will be obvious to some Im sure. thanks Mark

Here is how to do it: http://mopar.mopar1973man.com/cummins/2ndgen24v/reprime-fuel/reprime-fuel.htm

My problem is that as soon as I turn the key, the engine starts, no delay at al?

As quickly as you can, release the key as soon as you hear the starter engage, and the engine will not even turnover once or start but the pump will run for about 30-45 seconds.

[Flagman]

thank you so much, this is awesome! MarkFlagstaff, Arizona

[white01]

people call that bumpstarting!! good luck:thumbup2:

[Mopar1973Man]

people call that bumpstarting!! good luck:thumbup2:

Words of wisdom for ya... I alway though the same thing that bumping the start will prime the pump. But there is a small hitch... If you lift pump is producing less than 14 PSI worth of pressure during this time the air bubble will be trapped and your going to need to release the air bubble by pressing the schrader valve pin, crack a fuel line (big line kit). But other than that bubble will be forced up into the VP44...:banghead: Yeap I learned trhe hard way...

[Flagman]

Do I push the shrader valve while the engine is running. Would this be a good way to always purge the system of air? A quick question. Im wanting to try the oil in fuel combo. Is it 2 cycle engine oil or 2 stroke engine oil? thanks again for everything.

[Mopar1973Man]

Do I push the shrader valve while the engine is running.

No... Only during the time the lift pump is trying to prime. If you do it while the engine is running you might suck air in...

Would this be a good way to always purge the system of air?

Yes... Like I said bump the starter and push the pin in till good flow of fuel is seen...

A quick question. Im wanting to try the oil in fuel combo. Is it 2 cycle engine oil or 2 stroke engine oil?

Either both the same...

thanks again for everything.

Look here for both...

http://mopar.mopar1973man.com/cummins/2ndgen24v/reprime-fuel/reprime-fuel.htm

http://mopar.mopar1973man.com/cummins/general/2-cycle-oil/2-cycle-oil.htm

[SASQCH]

Words of wisdom for ya... I alway though the same thing that bumping the start will prime the pump. But there is a small hitch...

If you lift pump is producing less than 14 PSI worth of pressure during this time the air bubble will be trapped and your going to need to release the air bubble by pressing the schrader valve pin, crack a fuel line (big line kit). But other than that bubble will be forced up into the VP44...:banghead:

Yeap I learned trhe hard way...

Mike,

I know I'm not the smartest guy in the world, but just where is there a "Schrader Valve" in the fuel system?

Are you referring to the overflow valve on the VP44?

If so all of them that I've seen cannot be opened by pressing any pin on them.

Wikipedia defines a schrader valve as follows:

"The valve

A Schrader valve consists of an externally threaded hollow cylindrical metal tube, typically of brass. In the center of the exterior end is a metal pin pointing along the axis of the tube; the pin's end is approximately flush with the end of the valve body.

Generally, all Schrader valves used on tires have threads and bodies of a single standard size at the exterior end, so caps and tools generally are universal for the valves on all common applications.

A new development is Schrader valve stems with integrated transmitters for tire pressure monitoring systems (TPMS).

The valve cap

A valve cap is important on a Schrader valve because if one is not fitted, dirt and water can enter the outside of the valve, potentially jamming it or contaminating the sealing surfaces and causing a leak. Rock salt and other chemical deicers used in the winter are especially damaging for the brass components in the Schrader valve.

Metal valve caps usually have, in addition to a handy deflating tool, a small rubber insert to permit a good seal against the valve body; a cap of this kind also helps to prevent air escaping from a slightly leaking valve. However, the vast majority of Schrader valves used for tires are fitted with plain black plastic caps which effectively serve only to keep contaminants out of the valve stem."

Guess I'm confused as to what you are referring to as a Schrader Valve.

Got a picture of one?

Thanks

Jim

[Flagman]

thanks mopar man and everyone else for their feedback. The bleeding link is especialy useful. Question: with the schrader test valve instead of the banjo fitting, do we loosen the pin inside of the schader? Does the entire schrader assembly loosen to bleed?

I bit of information has made me dangerous.

---------- Post added at 06:13 PM ---------- Previous post was at 01:24 PM ----------

oops, saw your response and asked without reading it thoroughy. thanks, Ill give it a try.

[Mopar1973Man]

Just use your finger nail or a small screwdriver to puh the pin in... Looks just like a tire schader valve... Little pin in the middle must be pressed while the pump is running to purge the air.

Under the cap of #3...

[guesswho512]

mine didn't have a valve there. i know it doesn't now cause of the big line kit. have the lines and bangos in the garage. it is just a 17mm flat top bango

[Mopar1973Man]

mine didn't have a valve there. i know it doesn't now cause of the big line kit. have the lines and bangos in the garage. it is just a 17mm flat top bango

I guess you got the test ports in the fuel filter then?

If you got Big Line Kit then crack the elbow fitting at the vP44 for priing if needed... (Mine shown below)

[JoeDiesel]

i just installed injectors this weekend and to purge it i bumpstarted twice and had injector line #1 & #3 loose for a bit and tightened them up and worked fine.