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Posted: Thu Mar 08, 2018 10:58 pm
by UserError
Nearly there, I hope, although we can't make our first slot of Saturday to move her now:

I changed the primary filter today (appalling location, dreadful job), having previously done the secondary and then put 20l of diesel in with a shock dose of Fuel Set.

However, possibly along the lines of this by BobC, ... php?t=1782
I cannot get any fuel through. I pumped away for quite some while, having read that it can be slow to fill both filters.

It's hard to tell the relative level of the primary filter & tank - probably about level with the mid-point but there is a high(er) section in the pipe run between the tank & primary filter for some reason.

As my 20l Jerry can is on the boat and really not very handy, I can't easily get another load to fill the tank up and wondered if mildly pressurising the fuel tank would work to push the fuel through?
Something like a squishy foam ball with a hole put through and maybe any of the pumps we use on our Avon held onto the hole by a willing assistant. And block the breather off when I can find it ( I have seen a thin tube glassed in the stern locker with an inverted 'j' at top-is that it? I expected something bigger).

I could arrange this for our next visit if it would work. Any reason for it not to? Or its a really bad idea?
Many thanks

Re: Priming/bleeding

Posted: Thu Mar 08, 2018 11:21 pm
by TyroSailor
A dodge shown to me by an engineer trying to resurrect my old MD2B might work. He disconnected the pipe between the lift pump and injector pump and applied a suction pump - the sort used to suck oil out through the dipstick hole - to the pipe and sucked fuel through using that. Then he reconnected the pipes and turned the engine over - it started after several seconds' cranking.

Whether it would work on your engine is another matter - probably depending on the lift pump.

Good luck!

Re: Priming/bleeding

Posted: Fri Mar 09, 2018 9:12 am
by BrightStar
If you didn't fill the filters with fuel before fitting them there is a surprising amount of fuel needing to be pumped to fill them.

Are you sure that the lift pump is able to full stroke, try turning the engine a little if the lever isn't going full stroke.

How far has the fuel got, prime one filter at a time, the first filter is often lower than the main one.

If the filters are not priming then perhaps you still have a blockage in the inlet ( take the hose off the inlet side of the 1st filter and get the end below the fuel level in the tank - should flow freely at full bore - if not try blowing down the pipe. If thats OK then the lift pump may need looking at, the filter on that can get blocked or the diagram may be damaged.

I dont think its a great idea to pressurise the fuel tank!! Its not designed for that.

I hope you get it sorted on your next visit

Re: Priming/bleeding

Posted: Fri Mar 09, 2018 9:37 am
by Nigel Birch
Best thing would be get more fuel in there to get a sufficient "head".....

Re: Priming/bleeding

Posted: Fri Mar 09, 2018 9:52 am
by dj7613
First time I did it I couldn't understand why I didn't get fuel through. I was gently lifting the manual fuel pump lever up and down......wrong! You have to press it down hard to pump. None of the books I read told me that.

Re: Priming/bleeding

Posted: Fri Mar 09, 2018 12:40 pm
by UserError
Thanks kind sirs.

TyroSailor - thanks, I have such a pump. My (albeit limited) research suggests that a generic diaphragm lift pump has the inlet & outlet sharing a common cavity (rather than a displacement pump which might not) so suction on the outlet should pull the fuel through OK.

DJ7163, I'm pretty sure I was pumping OK - in the 20+ minutes I was doing it I tried a wide variety of pumping techniques!

Nigel, That's plan B, but a hassle as I've got to get out to the boat, get the can, back to the car, back to a petrol station & reverse - maybe an hour - and it still may not work (if blockage or some other reason). I didn't fill the tank as I was going to empty it again & give it a more thorough clean when I got to her new pontoon berth but I've got to get there first so it may be necessary.

Brightstar, I didn't fill the filters as the primary is very difficult to get at and the secondary isn't great plus I am wary of getting diesel everywhere as I can't easily clean up (me or the boat) where we are at the moment. I also recall a debate on YBW but can't remember the consensus that in a CAV filter, if you filled it you had bypassed the filter? After 20+ minutes of pumping, I undid the drain plug in the bowl & nothing at all came out... At that stage I gave up. We were in danger of running out of water at the slip & I was fed up, cold & hungry!

Next job is to troubleshoot the fuel lines as you say, starting at the fuel tap. Partly why I though applying a little positive pressure might help - the level of pressure one could blow like a balloon, other than it's a diesel tank. If there is a dollop of crud in the line, I'd rather it was ejected into a pot rather than back into the tank (which I have sucked empty & cleaned to some extent).

Many thanks

Re: Priming/bleeding

Posted: Fri Mar 09, 2018 2:14 pm
by Nigel Birch
In my experience on a Konsort with Buhk DV20 the CAV filter just fills up from the tank when you bleed the top of the CAV. There is no need to use the manual lift pump. So I reckon you have a blockage upstream.

Re: Priming/bleeding

Posted: Fri Mar 09, 2018 3:54 pm
by Fulmar433
I had a similar problem, unable to get fuel through until I did as Nigel suggests and vent the primary filter. Once that was full I was able to pump the fuel through the secondary filter.

Re: Priming/bleeding

Posted: Sat Mar 10, 2018 7:59 am
by UserError
Fulmar & Nigel, I tried that without success. Two reasons: one is that the fuel level is marginal at best - there is little or no head over the primary but the main problem is that for some reason the fuel pipe route takes it higher than the filter head. If I filled the tank it might overcome this high spot, so I may do that next.

Re: Priming/bleeding

Posted: Sat Mar 10, 2018 10:33 am
by TyroSailor
...and in the longer term, perhaps you could re-route the pipe?

Re: Priming/bleeding

Posted: Sat Mar 10, 2018 3:51 pm
by UserError
I can't see any reason why the pipe runs the way it does. I'm very comfortable with copper pipe working, so it's jumped to near the top of the list!
I might also put a priming pump in there. Anyone done this? Bulbs seem popular but apparently not approved? Inline or bypass?

Re: Priming/bleeding

Posted: Sun Mar 11, 2018 4:43 pm
by steve parry

I have this each year with my Volvo 2030, once I have changed the filters, with the tank switched off and the fuel drained from the fuel pipe etc I find it takes time for the fuel to filter through to the CAV (with the bleed hole open) sometimes it takes 3 to 4 minutes to fill up. It does help to have you tank full and with the system being gravity fed it does take its time.

I get over the problem by having a full tank always, more pressure behind the fuel wanting to get out of the tank! Or I turn the engine over for a couple of seconds and this seems to suck the fuel through to the filter and onto the engine, however, make sure the bleed screw is closed when you do this as you will only be sucking air into the system if its not.

I may be trying to tell you to suck eggs but it is worth a try.


Steve Parry - WALKABOUT

Re: Priming/bleeding

Posted: Sun Mar 11, 2018 5:05 pm
by TyroSailor
Hope you've had some success....

While you're disconnecting the filter and adjusting the pipe run, ist possible, I wonder, to move the filter to a more accessible position?

Re: Priming/bleeding

Posted: Sun Mar 11, 2018 9:50 pm
by Hillary
A retired Marine Engineer showed me a trick for bleeding the fuel line which is to crack open the first injector line and crank the engine over. The fuel pump should push the air out of the slackened injection pipe joint. You do have to be careful not to burn out the starter motor so you need to know how long you can turn the engine over without damage. You also have to be careful not to pump water into the exhaust so if the engine is not firing leave the water inlet cock closed until the engine starts. If the engine is running and you suspect air in the fuel line you can also do this trick while the engine is running.

Re: Priming/bleeding

Posted: Wed Mar 14, 2018 7:57 am
by UserError
Dj7163 :oops: I wasn't pressing firmly enough on the lift pump - it really is quite a pressure needed.

On the upside, I am now familiar with the fuel system. Never a bad thing!

I now have fuel delivery and an MD2B as I found the engine no. plate....

Thanks Hillary, I cracked open the injector & definitely got fuel.

Unfortunately the battery wasn't up to the job so I didn't manage to get it started.
New battery to be ordered.

I will move the filter, but not while the boat's in its current location as getting anything done is quite an undertaking. The bolts that hold the head to the wall have stripped so I need to do something. I've read of it being put on flexible hoses so the whole thing can be made more accessible too. I could mount it on studs glassed in, with butterfly or knurled nuts.