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Volvo MD5 fuel system getting air locked?


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#1 Alpha FB

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Posted 25 July 2013 - 06:20 PM

After discovering a fuel filter/separator full of some organic crap, I decided to clean out and change all filters on my Volvo MD5.  After the usual hassle of venting the system to get the air out, I managed to finally get the engine to run normally for 15mins to half an hour, before it starts to hesitate and eventually stops.  Reventing the fuel system enables the engine to be started again, but again, just for a liimited period.

 

I've gone through this cycle a lot over a few days, and am getting a bit frustrated, by now, and had to cancel my partipation in a classic yacht regatta this weekend.

 

One possible cause that crossed my mind was the fact that ambient temperature was quite high - but as far as I know, diesel engines don't suffer from vapor lock, do they?

 

Anybody any suggestions what may be causing this loss of fuel system integrity?



#2 Wreck™

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Posted 25 July 2013 - 06:50 PM

Reventing the fuel system enables the engine to be started again, but again, just for a liimited period.

Leak in the fuel system before the injector pump or unit injectors, it may not be dripping but air is probably being pulled into the lines somewhere.



#3 One eye Jack

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Posted 25 July 2013 - 09:04 PM

After discovering a fuel filter/separator full of some organic crap, I decided to clean out and change all filters on my Volvo MD5.  After the usual hassle of venting the system to get the air out, I managed to finally get the engine to run normally for 15mins to half an hour, before it starts to hesitate and eventually stops.  Reventing the fuel system enables the engine to be started again, but again, just for a liimited period.
 
I've gone through this cycle a lot over a few days, and am getting a bit frustrated, by now, and had to cancel my partipation in a classic yacht regatta this weekend.
 
One possible cause that crossed my mind was the fact that ambient temperature was quite high - but as far as I know, diesel engines don't suffer from vapor lock, do they?
 
Anybody any suggestions what may be causing this loss of fuel system integrity?

that organic crap might be fungus.. Does it look kind of white ? As for having to bleed your fuel system .. Almost sounds like you have an air leak. Check your fuel separator. Is it a racor? Because they can leak air. Check all of your gaskets, o rings and make sure everything is tight. I have seen brand new primary filters that have the petcock on the bottom, not be tight, but just snug.. And would suck air. What you can do isto bypass the fuel water seperator.. that will tell you if that is the problem, and possibly get you to that race. Good luck

#4 Alpha FB

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Posted 25 July 2013 - 09:45 PM

yep, was a nasty white fungusy type stuff - changed the fuel I had in the tank while I was at it.

 

I went through all the connections in the whole system several times without finding anything obviously at fault. 

 

Usually, when there is still a leak, it will show itself quite quickly, within maybe a minute or so.  What has me stumped, is that it all appears to work fine for up to half an hour before stopping...

 

Next time on the boat, i'll go through all the gaskets and rings again - seems to be the only thing to do...



#5 One eye Jack

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Posted 26 July 2013 - 04:12 AM

yep, was a nasty white fungusy type stuff - changed the fuel I had in the tank while I was at it.
 
I went through all the connections in the whole system several times without finding anything obviously at fault. 
 
Usually, when there is still a leak, it will show itself quite quickly, within maybe a minute or so.  What has me stumped, is that it all appears to work fine for up to half an hour before stopping...
 
Next time on the boat, i'll go through all the gaskets and rings again - seems to be the only thing to do...

if you don't.. You need to get an anti fungal diesel product. That fungus can be like a heart worm in a dog.. Just keeps growing until the dog dies. My ex father in law had it in his Mercedes , they had to boil out the tank and compleat fuel system ..the fungus may be restricting your fuel flow.. Where you buy your diesel talk to them about that fuel additive. Fungus just loves warm, dark, damp fuel tanks.. Typical boat in the summer. Just remembered the name.. Try Biobor. The airlines use it. Good luck.




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