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Fuel system air lock?


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Went to start our 2009 Monaco Knight 38PKQ yesterday With the Cummins ISC 360 HP and engine turned over fired and before getting up to idle speed (approximately 1-2 seconds) engine shut down.  No warning lights came on.  Engine turns over still but will not fire. Sounds to me like there is an air lock in the fuel system.  Has anyone else experienced this?  I cannot find the hand primer?  Does anyone know if this engine/ model has one!  If not, how would you correct this situation?

Any suggestions would be appreciated 

Thanks. Laurice

Laurice & Jennifer 

”Faith” our 2009 Monaco Knight 38PKQ 

Toad - 2016 Explorer

Fort Steele, BC

 

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Look for a second filter, my coach has one in the back next to the oil fill area and one on the side behind the air conditioner coils. Most Cummins have 2 filters and they usually don't have a primer.

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There is an electric fuel pump located right above the starter. Crack a line and turn on the key. If the fuel does not flow I would guess that. Had this happen to my ISC 400. Recommend you have a shop do it because starter has to come off. First I would do though is replace both filters in case you got a load of bad fuel. All the junk or water you might have picked up will settle on the bottom of the tank. When you first start the engine it will suck that up and plug your filters. If the problem happens with the new filters you need to drain and clean your tanks.

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Thanks for the advise.  Will try that this morning.  This could be the issue.  I made sure the water separator was drained completely in the fall but when I tried it on Tuesday there was a fair amount of liquid that drained.  Much appreciated 

Edited by laurice@email.com
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If there is an air leak what I am going to suggest will not find the leak, However, the quickest check is to prime the system with the ignition switch: Turn the switch to ON but not START. Wait either 30 ro 60 seconds until you hear the electric pump stop clicking. Turn off the key and repeat this priming procedure four more times. Then try to start the engine and see if it keeps running. In the process of this priming, I saw fuel leaking from a fitting (I was peaking under coach while my wife manned the key), A half turn of a wrench and I was in business for the next several years. Just a thoughht.

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I had that problem also.  try turning the key to on  then go to the engine compartment and start the engine from there.  you will find two switches together.  One is for starting the engine for the rear start or front start.  Put on rear start.  The other switch is the start button.  When you try starting it there you should hear a clicking noise keep holding it on.  After the clicking stops the motor should start if not you have problems listed above

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Try to find out what plugged up your filters. Drain them into a clear glass jar. Look for water or dirt. Cut open the primary filter and separate the folded paper element. You may have a build up of enough crud in your fuel that the pick up is getting it. This was pretty common in older trucks with the pick up on the bottom of the tank. They then went to a pick up tube from the top that stayed a couple of inches off the bottom of the tank. Still over time enough water would settle in the bottom of the tank over time to get picked up. I wouldn't make a very long trip without finding the problem.

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16 hours ago, gpafox@att.net said:

I had that problem also.  try turning the key to on  then go to the engine compartment and start the engine from there.  you will find two switches together.  One is for starting the engine for the rear start or front start.  Put on rear start.  The other switch is the start button.  When you try starting it there you should hear a clicking noise keep holding it on.  After the clicking stops the motor should start if not you have problems listed above

I have the same coach as Laurice. Ive heard of being able to start engine from rear but never have seen the switches. Does every coach have them?

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We don't have the ability to start from the engine compartment either. I think this feature would only be available on side radiator coaches. Not much benefit on a rear radiator coach since you must be inside the coach to have the engine exposed.

Bob

 

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6 hours ago, Bob Nodine said:

We don't have the ability to start from the engine compartment either. I think this feature would only be available on side radiator coaches. Not much benefit on a rear radiator coach since you must be inside the coach to have the engine exposed.

Bob

 

Bob

The  start/stop switches in the rear curbside service bay of my rear radiator Cat powered Safari are often used.

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  • 2 weeks later...

When draining the water separator, do it when the tank is full and the coach is level. I've heard air sucking in before when cracking the valve and not meeting these conditions. Doesn't take much air in the top of the filter to break the siphon.

From a previous experience running the tank too low parked on an incline, I learned the water separator must be removed and filled with fuel several times in order to get the primary fuel filter primed. I wasn't able to crawl under and fill the primary, but I'm sure that would have been faster. 

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At least on our ISX, the lift pump doesn't pull air well enough to prime the system with dry filters. Racor used to make fuel/water separators with a hand pump on them, but they appear to have discontinued those.

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6 hours ago, trailmug said:

At least on our ISX, the lift pump doesn't pull air well enough to prime the system with dry filters. Racor used to make fuel/water separators with a hand pump on them, but they appear to have discontinued those.

Our ISB is the same way. Our manual says not to prefill the filters, I assume for fear of contamination, but I have never been able to get the thing started without doing so.

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11 hours ago, Jim McGarvie said:

Our ISB is the same way. Our manual says not to prefill the filters, I assume for fear of contamination, but I have never been able to get the thing started without doing so.

Regardless the hotly debated point of pre-filling filters, there is one thing that can be said without argument:

"If you don't pre-fill your filters, your engine MIGHT still start.  If you pre-fill the filters, it WILL start."

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During this recent 'episode' with getting the MH started we ended up contacting the local Freightliner shop and they came out, removed the old filters and pre-filled the new filters before installing.  Once installed, we turned on the electric fuel pump twice for approx 15 seconds each time and voila ... started right up ... no issues.  According to the Frieghtliner trained mechanic, this is the way that he was trained by Freightliner to correct this situation.  

 

Laurice 

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