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Mark Hildich
Apr 19, 2014 - 3:06PM
Help Air in Fuel
Hi,
Any advice/help appreciated. After a long time out of the water and testing alongside. Finally, got everything together this weekend and headed out.. Unfortuantly, didn't get any further than the end of the pier at Portishead before engine lost revs, picked up again before finally stopping.. Cue heart stopping few seconds before engine restarted and we lost no time in retreating to back to lock.
I'm fairly sure its air getting into the fuel lines, but for the life of me, I cannot figure out where. I would like to strip out the lines (and also the tanks as starboard one seems to be seeping) but without removing the engine I can't see how this can be done. As I'm far from being a 2ft high contortionist.
I am loathed to lift out and remove engine given that we've just had the engine replaced etc (there was no hint of a problem then, nor with testing at the time) and just got Sulis shipshape again.
I'm toying with the idea of a temporary tank arrangement to at least see me through this season, or I suppose with a bit of a struggle, I could replace the current copper lines from the good tank with modern flexible ones bypassing the switch valves on starboard side and the seeping tank.
However, are there any better ideas??
Help Mark
SeaDog Name (if owner or crew) Sulis
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John Ingleby
Apr 19, 2014 - 8:30PM
Re: Help Air in Fuel
Has the fuel filter been changed? If so there could be a leak there. Either that or there was air still in the system after the change.
Apart from perished hoses on the suction side of the lift pump up to the tank changeover cocks there's not much else.
You can run off each tank in turn to see if there is any difference there.
While I'm here, can somebody tell me the prop diameter and pitch as fitted to a 4108 please? Anahita has suffered from a poor cathodic protection system.
SeaDog Name (if owner or crew) Anahita II
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Graham
Apr 19, 2014 - 10:49PM
Re: Help Air in Fuel
Hi Mark,
Sorry to have to confirm that there is no way a standard tank can be removed past a 4107 or 4108 at least, nor indeed a Betamarine BV1505 (the engine we currently have in Dougal).
Do you know where the fuel return is on your fuel setup? Many SeaDogs originally had the return to a 'spare' connection on the water separator, an 'impossible' arrangement according to marine engineers that seemed to function very well for 30 years! The problem with running from the port tank alone (for example) might be if the fuel return is to the starboard tank only.
On Dougal we have twin diverter valves so that the fuel always is returned to the tank it came from, all done with modern nylon fuel lines (I think they are nylon anyway, certainly not metal).
It does sound like either air getting into the system, or possibly not enough air getting into the breather on the tanks? Do you have the original arrangement with a saw cut through the filler caps? Yes it worked but not recommended, Dougal now has dedicated breathers (installed when tanks were replaced in 1996) that lead to the highest point in the steering binnacle.
Hope this is of some help, keep us all updated, hope your next trip goes better.
Graham
SeaDog Name (if owner or crew) Dougal
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Mark Hildich
Apr 20, 2014 - 9:47AM
Re: Help Air in Fuel
Hi,
We replaced the 4108 with a Nanni 38Hp, but as you say its impossible to remove tanks. We also replaced the filter at the time and fuel lines from the filter to the engine and they aren't perished.
We also have twin diverter valves to return the fuel back to the tank it came from, with the original metal fuel lines.
At the time a visual inspection and testing seemed to indicate all was well.
However, in hindsight, I should have had the tanks out for proper testing and replaced the old fuel lines between the filter, diverter valves & tank.
I think at the moment, my best option is to isolate and drain the starboard tank, take the old fuel lines out and just bypass everything using modern fuel lines. Which I hope can be done in situ with a bit of contortion and will get me through the season.
Regards Mark
SeaDog Name (if owner or crew) Sulis
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Phil
Apr 20, 2014 - 5:09PM
Re: Help Air in Fuel
Hello Mark
The tanks will not introduce air into the fuel, Graham was right about the tank vent, if breather slot is blocked a vaccum will build up and stop the engine, it then recovers and the engine will restart and run again for a short time.
If any of the fuel joints or filters were disturbed durring the winter that is the first place to look for an air leak. In the low pressure side of the fuel system the other item to look at is the fuel lift pump diaphram (this could also allow fuel into the oil sump so also check the dipstick to make sure nothing is adding fuel to the oil level)
When we fitted our new engine last year I checked over the fuel tanks (and replaced all of the old copper fuel pipes with modern rubber) I was supprised to see how good the condition was inside and out.
email me if you need fuel a pump or and injector I have a serviced spares left over from my old Perkins spares box that you are welcome to.
Good luck
Phil
SeaDog Name (if owner or crew) Soyakaze
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Mark Hildich
Apr 21, 2014 - 4:20PM
Re: Help Air in Fuel
Hi,
As you say, the filter and fuel joints were the first thing I checked. I've also checked oil levels and condition of the oil and all seems ok in that department.
Thanks for the offer of spares but as I said the engine has been replaced by a Nanni.
There are a couple of other symptoms which concern me
1 Below the starboard tank is what seems to be a continuous seepage of diesel.
2 Another, is that having set the diverter valves to use the port tank is that it seems that a suction appeared on the starboard tank, in that I was unable to remove the filler cap to check diesel level, until the next day. (seems to contradict the seepage symptom tho').
I suspect this tank does not have breather.
Also the level of diesel in the Port tank rose slightly but this was within measurement error. So difficult to confirm.
My suspicion is that the diverter and fuel lines have been altered and although they seemed ok to me and the guy who installed the engine. Something has been changed.
I suspect this might be why the engine stalled... possibly... in that it was drawing from the stbd tank and discharging to the port tank.
I'd dearly love to take out the valves, the old fuel lines, but access is difficult and despite playing around with a camera etc. A visual inspection hasn't found anything.
SeaDog Name (if owner or crew) Sulis
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Phil
Apr 21, 2014 - 9:01PM
Re: Help Air in Fuel
Hi Mark
Soyakaze never had a diverter valve just two simple on / off valves on each tank with two fuel pipes routed to the CAV first filter / water sep. When we had the new engine fitted I asked the SAL Marine engineer about fitting a diverter valve and his advice was that he always removed them if fitted as they were nothing but trouble.
Also on Soyakaze (hull 104) the fuel return only ever went to the port tank there are no fitting on the stbd tank, the fuel levels are balanced I assume by the joined feed.
I would be tempted to run the fuel directly from the port tank only using new rubber tube and if this works the problem is issolated and you could rig up a pressure test (using an air pump) on the stbd side.
Good luck
Phil
SeaDog Name (if owner or crew) Soyakaze
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Paul
May 25, 2014 - 8:17AM
Re: Help Air in Fuel
Hi Mark
I have had a problem when running on the port tank and the level went below 3/4 of a tank, I tried this winter to sort this as this has been a on going problem. It was down to the diverter valves in the bottom of the locker, one had a missing spring washer and the other had a split rubber washer. When I put it all back together I used a little blue hylomar on the shafts of the vales and a little grease on the under side of the caps which hold it all together. So far this season its been ok the engine has now run 15 hrs with no problem.
SeaDog Name (if owner or crew) Melisse
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