Fuel flow problems

[rajjes]

Hi,

This weekend I was motoring out and the engine (Kubota z482) slowed down and gradually died. I tried restarting, which id did but after a few seconds it died again.

After a nervous sail back to the mooring I went to investigate and found that the rubber squeeze type pump (as used on outboards) was totally collapsed under suction which shows an obvious problem with fuel delivery.

Upstream from this priming pump there is the primary filter, shutoff valve and intake to the tank. I have replaced the entire system last summer (including the tank) so am really puzzled what could be causing this blockage. I’m thinking it might have picked up something from the tank and blocked the pipe?

So, any tips before I start dismantling? I do not want to simply clear the blockage by blowing it back in the tank. Could it be the squeeze pump valve that has failed?

 

[No Regrets]

Tried loosening the fuel cap to see if a breather is blocked?

 

[rajjes]

Yes, forgot to mention it was the first thing I checked together with any obvious kinks in the fuel hose.
thanks,

 

[dickh]

Interesting that you have an outboard squeeze bulb for fuel? You do not usually have this on an inboard diesel. Does the fuel cap does have a breather hole? Is the tank vented? If all OK then it seems as though you have a blockage somewhere and I suggest it's from the tank to your primary filter(the filter will have stopped most smaller bits) - you'll have to dismantle the pipework and bloww all the pipes through, and of course change the filter.
Also make sure all the unions are tight and you don't have a small air leak - I had this problem soon after I installed a new Beta engine, it would start then stop soon after. After speaking to the Beta engineer I tightened all the unions, AND bled each injector as he said that Kubota engines can collect an air bubble in the injector. I did all that including bothe filter changes and it's been fine ever since. Good Luck anyway.

 

[savageseadog]

You could have loose material in the tank such a rust/paint flakes or a piece of polythene or PTFE tape. It could be waxy deposits or slime from bacteria. Suggest you clean the tank out very carefully first and check that the outlet is free to flow and check the fuel cock. Any plastic or flexible lines could be kinked.

 

[FulmarJeddo]

Years ago I had an outboard that would cut out due to fuel starvation. That turned out to be one of the non return valves in the rubber bulb coming apart and reversing itself. I think my one was the outlet valve, but it could be the inlet valve stuck if the bulb is collapsing.

 

[vyv_cox]

Is the filter bowl a glass one? Can you see if the filter is clear? If not, I would open that first. I don't know how long it takes diesel bug to develop, and in your case it has only been a year or so. However, the symptoms you describe are very similar to those I have experienced with a severe dose of gunge in the primary filter.

 

[Artemis_C2121]

you dont mention if you have been using the boat since you replaced the fuel system if so I would recommend that you remove the bulb from the system it may be the cause as previously suggested and should not really be needed anyway, apart from that likely cause is debris as suggested .

If this was your first serious use of the engine since you renewed the fuel supply check that the pipe work is connected to the correct positions on all the bits and pieces, one other thing i have come across a few times is that the fuel lift pipe inside the tank is too close to the bottom of the tank, when the engine (and fuel) system is at idle or low load no problem however when both are worked a harder the fuel pipe actually sucks the bottom of the tank and covers to pick up. have seen this catch a few people out as when dismantled there is nothing to see.

Good luck
Neville

 

[rajjes]

Thanks to all for replying.

I have been using the boat so I don't think it has a faulty installation. I will remove the bulb first, then check the intake. Let's hope its not the bug...

btw I had placed a bulb as I don;t have a manual pump with the filters or lift pump.

cheers,

 

[DavidMcMullan]

You can get hand primers, which fit on to the inlet or outlet of a primary filter. For an example, see www.asap-supplies.com, then 'CAV type filters', then 'Hand Primers'. These do not collapse, if there is a vacuum pulled.

 

[mtb]

it may be
because you have fitted a bulb that the flexible pipe has collasped inside.
I'd not have a bulb fitted on a diesel fuel system once the fuel system is installed as it should be then there should not be a need to prime the system unless there is a fault !
As others have said if you want a primer get the correct type that fits to the filter head

cheers
Mick

 

[Stoaty]

[ QUOTE ]
Interesting that you have an outboard squeeze bulb for fuel? You do not usually have this on an inboard diesel.

[/ QUOTE ]

It's quite common on commercial fishing boats. It's used to prime the filter/ bleed the system easily and quickly.

 

[DaveS]

Well in support of rajjes, I fitted a bulb to my system a couple of years ago and it works just fine, making it much easier to fill the primary filter (higher than the tank). Certainly a damn sight easier than blowing down the tank breather which was the previous method! I had originally intended to replace the filter head with one having a priming pump, but a number of bad experiences posted on here by people who had gone that route put me off.

Incidentally, I fitted the bulb as part of a complete overhaul of the suction pipework, during which I discovered a largeish bit of plastic jammed into a fitting, reducing its diameter by over 50%...