3126 Fuel Filter change

[boyland]

Well we have done this many times but yesterday is the first time i ever got an air lock in the system.

We eventually loosened the large nut close to the intake to let the air out.

And she sputtered then started.

Everything back to normal.

But for the life of me I have always primed these filters and did so this time I also make sure the tank is fuel just in case of drain back. Still a little puzzled on how it got a enough air to lost the prime.

Kinda of a question if anyone else had this happen

[Skip426]

Isn't there a manual prime pump on your fuel system ?

Only one filter on your coach ?

[CountryB]

On the back of the head is a fuel pressure regulator.

I believe this also acts as a "check valve" to prevent the fuel from draining back out of the head's fuel rail. So possibly that check valve is leaking internally and the combination of changing the filter and the head draining caused your hard start.

I can't find the info now on the check valve, but I think it was said that this regulator/check-valve was only around $40 so, it may be worth replacing just for peace of mind.

Maybe member "Cat" knows for sure whether or not there is a check valve at the back of head - and if it's worth changing.

[boyland]

Answer the question about pump the answer is no they do not have these are single filter freightliner cheaped out lots of people have had issue because they try and start them dry which will lose prime for sure.

Anyways I will see if cat has a thought

[New 2 Newmar]

Originally Posted by boyland

We eventually loosened the large nut close to the intake to let the air out.

And she sputtered then started.

Everything back to normal.

Forgive me for asking, I'm kind of a visual guy..... can you post a picture of this large nut so I know what I'm doing if it ever locks on me?

[Cat]

Some engine did have the fuel pressure regulating valve at the rear of the head. Some were at the front. Give me engine serial number and I'll take a look at the locations. Safe Travels

[New 2 Newmar]

Originally Posted by Cat

Some engine did have the fuel pressure regulating valve at the rear of the head. Some were at the front. Give me engine serial number and I'll take a look at the locations. Safe Travels

Thanks Cat. Mine is 8YL67426 Always good info to have.

[Cat]

Odd picture but it does look like the fuel relief/check valve is at back of the head. And it sets the fuel pressure and acts as a reverse check valve to keep the fuel from draining back to the tank when shut off. Its item 11. Safe travels

[boyland]

Originally Posted by New 2 Newmar

Forgive me for asking, I'm kind of a visual guy..... can you post a picture of this large nut so I know what I'm doing if it ever locks on me?

Next time I have the covers off I will

Cat serial CKM31166

[Cat]

Originally Posted by boyland

Next time I have the covers off I will

Cat serial CKM31166

Item3
Safe Travels

[New 2 Newmar]

Originally Posted by Cat

Odd picture but it does look like the fuel relief/check valve is at back of the head. And it sets the fuel pressure and acts as a reverse check valve to keep the fuel from draining back to the tank when shut off. Its item 11. Safe travels

Ha, great, thanks cat I do appreciate it. It's kinda like the doctor delivering your baby and saying ummm, here you go then run out of the room. lol.
Yup that's my babies diagram. I don't see item 11. I must be missing some fingers or toes on my newborn. She definitely needs a nice gentle scrub bath after I get my HEUI filter back on.

[Cat]

Originally Posted by New 2 Newmar

Ha, great, thanks cat I do appreciate it. It's kinda like the doctor delivering your baby and saying ummm, here you go then run out of the room. lol.
Yup that's my babies diagram. I don't see item 11. I must be missing some fingers or toes on my newborn. She definitely needs a nice gentle scrub bath after I get my HEUI filter back on.

Opps cutoff bottom of picture. Its located at the bottom of the picture with the filter superimposed on it

[New 2 Newmar]

Why? Its just my foot in a clean sock lol.

edit: oh wait you meant your picture haaa

[CountryB]

I could not see an "item 11" or an "item 3" in either photo - so here's my attempt to show the Fuel Pressure Regulator on the back of cylinder head: