Fuel Line Air Lock

[Pete Smith]

Greetings.  I just replaced the fuel filter gasket. (It was leaking a little) I put the empty fuel filter in and forgot to purge the air out of the filter.  The Beaver started and ran for about five minutes then quit.  Now it won’t start at all.  I have read many things about not doing this but not much seems to address what to do if it happens.  Do I have to bleed the air out of the injectors? If so, where are they? Is there any other thing I can do to get it running again? The engine is a CAT Straight 6, 3126B 330 HP in a 2000 Beaver Patriot Ticonderoga motorcoach.
Thanks in advance. 
Pete Smith

[Frank Bergamo]

Pete,

Do you have a mechanical primer pump? It will be mounted on the fuel filter housing. Also, at this point I would  pull off the filter and fill with diesel fuel. Hopefully this will get you going.

[Eric Maclean]

Pete
Your coach should have a Racor water separator with a priming pump .
If so turn the ignition on and go to the service bay where you will find the control panel for the Racor filter system on it there will be a priming button .
Push the priming button you should hear the pump in the filter housing run.
While running the priming pump loosen the secondary ( CAT) fuel filter and run the pump until that filter is full and fuel runs out of the top then tighten it back up.
After that run the priming pump several times to push fuel through the fuel rail in the cylinder head and back to the tank via the return line .
It may take several cycles of the priming pump
After the fuel rail is charged with fuel the engine should start and run.
 It is not uncommon to have an air leak at the Racor water separator allowing the fuel system to suck air instead of fuel from the tank.
There have been several threads here on the Racor water separator and air infiltration causing lack of power and no start problems
There is manuals for the Racor system in the coach assist library

Hope this helps
Eric

[Pete Smith]

I do have the Racor water separator.  That is why I am having this problem.  The gasket that came with the RK12963 Retrofit Kit was too thick to assemble the unit - Not enough threads to start the filter so I used the old gasket.  That leaked after a while.  When I was getting ready to sell the coach, I decided I should fix that small fuel leak before turning it over to the new buyer.  I used a table saw to thin out the new gasket a little and replaced the old gasket with the new modified gasket.  When I originally did the retrofit, I had a full tank of fuel and pressing the Schrader valve on the top of the filter let out the air.  This time I only have a half tank of fuel and pressing the Schrader valve didn’t do anything.  I have a small control panel in the service compartment that says “Air Purge” with a button and an amber light that lights when the button is pressed. There is a button marked H2O purge with an indicator light above it.  There is an indicator showing H2O and an indicator showing Power.  It is green.  Pressing the Air Purge seems to have no effect other than turning on the amber light above it.  If there is a pump of some kind that is supposed to start, I can’t hear it. 
After replacing the gasket, I operated the Schrader valve to no effect and started the engine.  It ran for about five minutes and then quit.  I had time to watch it for a little while and then walk down into the basement before it quit.
I am pretty sure the filter is full now, the air has gotten farther into the works.
Turning the ignition key to “ON’’ but not “Start” doesn’t start any discernable pump either.  I had my wife do that several times while I listened to the fuel filters with a mechanic’s stethoscope.
My next step is to crack the fuel line where it goes into the back of the engine and have my wife crank the engine to see if I get any air there.
I’m hoping I didn’t fry the fuel pump by running it without fuel. Will get back to you tomorrow an how that worked.

[Eric Maclean]

Pete
The priming pump is built into the Racor filter base and is easily heard when it runs.
It sounds to me like your pump is inoperative.
The fuel line at the rear of the cylinder head (under the bed ) is the fuel return line , the fuel pressure regulator is located there as well.
 if you are going to remove that fuel line to try to get the systems mechanical pump to push fuel through the head you will want to remove the fuel pressure regulator as well to remove the resistance and let the air purge out. this will allow the gear pump on the back of the HUEI pump to move fuel through the filters and up through the cylinder head gallery more easily while cranking the engine .
Once fuel is running clear out of the rear of the cylinder head while cranking stop and reinstall the pressure regulator and return line then try to start the engine .
This is far from the preferred method but it should do the trick
The engine may crank a while before starting as you will not likely get all the air out and it will run rough for several minutes while it moves any residual air out of the system.

Hope this helps
And Good luck
Eric

[Pete Smith]

The fuel line at the back of the engine goes directly to the secondary CAT fuel filter. I don’t see any pressure regulated there. I tried sucking the air out of the fuel line at the engine block with one of those brake bleeder kits. It did pull fuel through the Raycor unit and I got fuel up to the point where it goes into the engine but lost everything while I was screwing the line back onto the back of the engine. I think I’m going to remove the whole Raycor unit, take it to the bench and see if I can’t get the pump to work. That would be the best thing. If it isn’t repairable I might just bite the bullet and buy a new one. Wish there was someplace to get it faster than ten days. If I can’t fix it maybe I will contact the local Caterpillar parts store. I’m in Peoria. Lots of Caterpillar stuff around here.
I hate opening the line right by the engine. Too easy to get a little dirt in there.
Thanks for the help. I will keep you posted. Maybe take pictures of the inside of that Raycor unit.

[Frank Bergamo]

Here is a manual primer pump. It mounts on your fuel filter housing. Remove the plate and install. This will get you going until you figure out what direction to go. Fairly cheap. Hope this helps. https://www.heavydutypros.com/caterpillar-priming-pump-1052508.aspx?utm_medium=paid&utm_keyword=&utm_source=google&utm_campaign=17501878712&utm_network=x&utm_placement=&utm_source=&utm_prodid=149282&gclid=Cj0KCQjwqs6lBhCxARIsAG8YcDi9ndVqI7jxrIkO1kwat2Fwj9XNcQPEZtq0t9s76U-c-glzu0tDJVwaAiQkEALw_wcB

[Pete Smith]

Thanks to both Eric and Frank.  Knowing the Racor purge pump wasn't doing what it was supposed to do and the part number for a manual replacement was all I needed.  The local CAT dealer had the pump in stock and it was a thirty minute install (I don't work fast - I'm retired)
I pumped it up and the bus started right up.  Thanks again.

[Frank Bergamo]

Very nice! I love it when a plan comes together.