How to vent the fuel system correctly? And, where to buy a venting screw (bleeder screw)? I break one just now!.

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Boater On Thames

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As tilte mentioned. Need help! I should not use a big wrench to tight the venting screw!

My engines are Volvo TAMD61A. Just replaced all the fule pre filters and fine filters. I follow the manual instruction open the venting screw at the fine filter, hand pump until runing fuel, close the venting screw, pump another 20 or more. Engine started okay, but it will stop after a few seconds running. Redo several times, the same result everytime for both engine. So I think the fuel is not running. Is my operation correct or wrong? What can I to to solve it?

Sadly I break the port side venting screw when I do the last try just now. Can't find where to buy one!

Many thanks.
 
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There’s a bit of a knack to this .



Best done with the tank level higher than the Racor .

Turn the tank cock off .

Swop filters taking care to refit the new o rings in the Tee and lid and seat them properly.

Turn the fuel tank cock on slowly ...gravity will fill the racor .Gently finish righting the lid down as you see fuel reach the brim and spill out the top .Ok use a rag to catch it .

Your racor is now full.



But the pipe from the racor to the secondaries on the engine ? Maybe air ?



Swop the engine cartridge(s) ....I lightly oil the o ring with dip stick oil , both sides .

I also go to a garage with 5 L can ( carry it on board ) to get some diesel .

Before screwing up the canister I fill it from the Jerry can ...steady hand then fit it trying not to spill .

Have to turn the ignition on to open the electric fuel solinoid on the injector pump .

It won’t prime without the ignition on as no fuel will be sucked .



Then using the priming pump after undoing the 10 mm spanner bleed screw it just takes 4/5 strokes if that for the bubbles to turn into a flow .Nip up done .



Fires up as if nothing’s happened.



I have never done it with empty cartridges/ racors , so I don’t know how long or how many pumps it takes to fill a racor 900 + 2x engine spin ons .
 
Hi Markc, that is Great! Thanks.

Hi B, it's a Racor 900MA. I filled it before I do the hand pump every time.

Hi Portofino, thank you for your input. I found I have no tank cock at the tank, but have some switches in the engine room to choose how to connect two tanks to two engines. From what you said, I think the pipe between the tank to the pre-filter is empty. So every time I refill the pre-filter then the engine start and run for a few seconds, then the pre-filter fuel level go low. I will have to refill the pre-filter to make the next start. Looks like the engine only got a little fuel from pre-filer! Now will be a challenge for me: how to full fill the pipe between the tank to pre-filter!! Any idea?
 
What’s the height difference ?
There should be a tank cock otherwise how could you change the pipe ?

Sounds like air is leaking in .
The spin ons recheck the o ring ....ie have you removed the old ? Because sometimes the old one stays on the housing up out of sight .
Then you inadvertently tighten up a double o ring set up .Feels tight and appears not to seep fuel ......but sucks in air and when the air stops the engine some goes back .
If the pump ( injector pump not the bleeding pump ) gets air which it will with air leaky fittings then that’s gonna take a lot of engine turning and stuttering for it clear .
Air leaks allow the racor siphon out back to the tank possible ?
 
Looks like my tank at the lowest point of the entire fuel system. The tanks about 30-40 cm lower than the pre-filter. The fine filter about 40 cm higher than the pre-filter. Can't see a tank cock. There are two pipes from each tank connected to the switches which can choose either port tank feed port engine, starboard tank feed starboard engine, or select any one tank feed both engines.

Maybe I have to double check again tomorrow. There are too many pipes I could be wrong.
 
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My Racor is in a fairly inaccessible place so I fill an old 1l oil container, the type with a long bendy filler tube, with diesel and use that to prime the Racor and also the engine spin on filter. No drips or spills (y)
 
When manually pouring diesel into a filter, is it still filtered or has it bypassed the filtering bit? If so, small risk of unfiltered fuel being bypassed on the initial start-up, just a thought.
 
Hi Scubadoo, will pouring the diesel to the Racor filter is only filling the filter, the diesel not going anywhere else.

Hi Portoinfo, I double checked again today. There is a tank cock hidden close to the inlet pipi. So my tank has 5 pipes connected. One biggest pipe for the fuel inlet. Next to the biggest inlet pipe has one small pipe with cock. Next to the cock, there is another pipe with no cock. And two more pipes with no cock at the other side of the tank (don't know what that for).
 
Bought a new venting screw from a local store yesterday. But I still can't prime the fuel system. The venting screw only pump out the little fuel in the Racor pre filter. After the pre-filter fuel run low, there is no more fuel come out to the venting screw. And the system will only have bubble sound when I do the hand pump. So I think there is no fuel coming in between the pre-filter and the tank but air only. Then I removed the tank level sender, found the sender is wrong. It is a wrong length and wrong resistance type, so it signals the gauge shows 75% fuel which is wrong. I measure the tank about 33cm depth, and the fuel only about 10cm left. I think maybe the fuel level low make the prime not working? And I think maybe this is the reason the starboard engine get air in to the system at the first place. Just a thought.

Will the 10cm fuel level in a 33cm tank too low to pump? I will refuel it afternoon anyway as I have half tank fuel storage in my two drum barrels.
 
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Lucas Gan said:
Bought a new venting screw from a local store yesterday. But I still can't prime the fuel system. The fuel system only pump out the little fuel I refill to the Racor pre filter. After the pre-filter fuel run low, there is no more fuel come out to the venting screw. And the system will only have bubble sound when I do the hand pump. So I think there is no fuel coming in between the pre-filter and the tank but air only. Then I removed the tank level sender, found the sender is wrong. It is a wrong length and wrong resistance type, so it signals the gauge shows 75% fuel which is wrong. I measure the tank about 33cm depth, and the fuel only about 10cm left. I think maybe the fuel level low make the prime not working? And I think maybe this is the reason the starboard engine get air in to the system at the first place. Just a thought.

Will the 10cm fuel level in a 33cm tank too low to pump? I will refuel it afternoon anyway as I have half tank fuel storage in my two drum barrels.
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You could have a hole in the tank pick up pipe that is drawing in air. Can you rig a temporary fuel line from your fuel drum to the Racor? If this works you have an idea where the problem lies.
 
Lucas Gan said:
Maybe. But one thing confused me is that the two engines was using the same tank while one get air in, and another one no problem.
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If that if definitely the case and both engines using the same tank pick up then you need to look elsewhere.

I think it's great that you have gone the DIY route, but now might be a good time to get in a pro to fix this issue and give you some good advice for maintaing your engines in a stress free way in the future
 
Good remind.
I further found the tank actually has 4 pipes into the fuel bottom. Plus one inlet, one vent pipe. So total 6 pipes connected. Maybe the two engines using different puck up pipe as there are total 4 there. I will have to dig in to figure it out.
 
Ok. I figured it out all the pipes finally. The extra 2 pipes is for the generator.
And I think the reason prime not working is fuel too low. I finally can see there are only air bubble come into the pre-filter while doing hand pump for the port engine. I previously only worked on the starboard engine so can't see the pre-filter while I hand pumping as they are on a different side. But now I see it while working on the port engine as the pre-filter and hand pump on the same side. Good enough for today. Continue to refuel tomorrow.
 
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