Unpractical boat owner: bleeding diesel lines

[Reptile Smile]

Hi all,

Apologies for my gross stupidity. It's quite possible I'm too dumb to be allowed to own a boat...

I've recently had to change my fuel send and return hoses from my tank to be ISO fireproof hoses. After having done this, I then couldn't get my lines to either bleed satisfactorily or the engine to start. Any help would be gratefully received.

https://picasaweb.google.com/lh/photo/lSqV5SwQqkiUGVqSuR4gidMTjNZETYmyPJy0liipFm0?feat=directlink

I presume the 'device' in the centre bottom of the picture is the fuel pump and the plastic disc to the right of this is the 'button' for the manual pump. I cracked the small nut on the top of the fuel pump as being the most likely 'bleed nut' location, but no matter what I did, whether priming the manual pump, or cranking the engine over til I ran out of battery, nothing resulted in the engine starting, or any fuel appearing at the bleed nut.

1) Is there a different bleed nut I should be using?
2) I connect the fuel line from the bottom of the tank/tap to what I presume is the fuel pump. I have got them the right way round, yeah?
3) Is convention with taps that 'in line' with the pipe is 'on' whereas at 90 deg to the pipe is 'off'?
4) Is there anything else I should be trying?
5) Am I too dumb to own a boat?

 

[wotayottie]

The picture isnt big enough to give you specific answers but:

1/ the pipe route is from the tank to the lift pump to the engine filter to the injector pump to the injectors.
2/ you dont usually need to bleed the lift pump.
3/ normal route is to open the bleed screw on the engine fuel filter and then pump the diesel though by hand ( little lever or button on the lift pump) until clean diesel is coming out of the bleed screw with no bubbles in it.
4/ key issue is that all joints should be air tight
5/ not recommended to try and purge the fuel system of air by using the engine starter since you can flood the engine with coolant water by doing this.
6/ no- chasing the air leaks in the fuel system can be a PITA for any of us.

 

[Reptile Smile]

Sorry - I typed 'bleed nut on the fuel pump' when I meant 'bleed nut on the fuel filter' - stupid of me. Still can't work out, though, why I couldn't get fuel to appear there...

Thanks for the guidance - much appreciated

 

[Otter]

Once spent two days trying to bleed a system - turned out there was a pinhole leak in the lift pump.

 

[wolf]

feed and return

You have the feed and return pipes on the right fittings ?.

 

[Rossynant]

First check if the fuel gets to the pump at all... or after the pump, where easier.
Just disconnect some hose somewhere before the engine filter (or pump). I have no idea of this engine.
Is there a primary filter before pump? May be this is involved. May be the fuel goes through a siphon - upwards from tank, and there is an air buble preventing siphoning.

 

[nigel1]

Not able to view the picture, but on my VP engine, crank shaft has to be in a certain position for the lift pump to work, guess there must be a cam involved somewhere.
If you can feel no or little resistance when operating the lift pump, may need to rotate the engine until you do. I used a socket and ratchet drive to turn the engine while operating the lift pump lever until some resistance is felt.

 

[Lakesailor]

I thought that, but he has tried cranking the engine to bleed.
It does sound like there is an air lock before the lift pump.

 

[Chalker]

Partially open the joint at the pump output - are you getting fuel pumped through?

Close that one and open the joint at the filter input - are you getting fuel pumped through?

Is there a filter between the tank and the pump? does it have air in it? Is it below the fuel level? You may be able to fix this by filling the tank.
You cannot bleed this filter with the pump, it is sucking on that side and will happily suck air in! You'll need to pressurise the tank outlet to this filter.
1. blow in the tank breather. 2. fit an outboard sqeezy hand pump. 3. fit a small electric fuel pump.

 

[PilotWolf]

Not to be patronising but...

- is there fuel in the tank still.
- is there a tap you turned off to stop the tank emptying when you changed the pipe?

W.

 

[Daydream believer]

If you have a dinghy pump stick the hose in the filler of the tank & seal by stuffing rags round it. Seal off the tank vent
Open all the bleed screw & get someone to pump the pump to pressurise the tank. This will force fuel through the bleed screws in turn which you close off as the fuel in each one starts to flow without air bubbles. This way you can get air right up to the final filter plus if the injector pump has a bleed screw it should come out there as well. After that you have to follow the instructions for bleeding the injectors

You may find the fuel does not go past the pump. If so turn the flywheel half a turn

I am assuming you have some fuel in the tank & all connections are tight.!! Tank shold be clean & filters fairly new. Pumping the fuel pump by hand is a pain & overuse of the starter can burn it out. Do not run for more than a few seconds at a time

 

[Daydreamer]

Fit a primer such as here

Or a primary filter with a primer built in or as others have suggested, an inline bulb type.You'll be lucky to get a lift pump to drag fuel through a conpletely empty system.

 

[KellysEye]

There should be a bleed sscrew on the engine, open that. There should be a lever on the fuel lift pump, pump that until all the air comes out and diesel appears. For anyone with a Racor filter it has a more powerful pump than the fuel lift pump and is thus quicker.

If that doesn't work you have an air leak somewhere. You can normally check for air by puttting talcum powder around all joints and anything else that could leak such as the bleed screw and filter(s), however if there is absolutely no diesel in the system then it won't work but try it anway in case there is some diesel residue.