DF50 - 2008 - air in fuel filter

[mike.floutier]

Hi, just doing my weekly flush and noticed a variable stream of air bubbles passing through the low pressure filter.

I changed the fuel line over to the spare but it's the same issue.

Obviously it it means there's a leak somewhere between the tank and the filter.

Any suggestions how to proceed?

[artdf175]

Mike.. it should be just a matter of checking all the fuel hose clamps..
I would start at that inline fuel filter and work backwards to the tank.

then the fuel/water separator filter to make sure the gasket is good
and the fuel line connector on the front of the engine, if there is one.
(some models the fuel line goes from the fuel bulb directly to the inline filter)

Art..

and with the age of the fuel line, check the condition so there are no kinks or the like that could compromise it.

[mike.floutier]

Many thanks Art.

Is it possible that it could be an airlock that is just moving around in the flow? The exit of the LP filter is a local high point.

[artdf175]

I would think not.
the engine would suck any air bubble out fairly quickly.

[mike.floutier]

Thanks Art, that was my gut feeling also, ie. "Surely if the fuel is being sucked through the system by the pump THEN the air will simply be flushed along with it and finally out through the injectors".

However, I had heard about AIRLOCKS and googled it and found this - https://youtu.be/r_lrR_Y4_UM - apparently air will get trapped at a high point and NOT be flushed away.

So, where am I now? I now know I do have an AIRLOCK.

But, I may OR may not have a leak.

If I don't have a leak then purging the airlock will stop the recurrence of the air bubbles I'm seeing. So this will be my next step (I will still check the condition of the fuel line, as you suggested Art)

So, how to get rid of airlock(s), bearing in mind they could be in any "high" part of the system?

I will google this but if anyone has hands on experience, esp with a DF50 - 2008 or similar....

[Moonlighter]

By far the most common cause of air in fuel lines is a leak at a join.

Don’t fixate on an airlock, much less likely. These fuel systems are designed to purge air as you would expect. Hence you see the bubbles continuously moving through.

First undo all joins and inspect the hose condition under the hose clamps, and check the seals on the water separating fuel filter.

The air could be getting in anywhere between the fuel tank take off fitting and the engines VST. I would start at the tank and work towards the engine. I bet you find it either at the tank fitting or the filter inlet or outlet.

[Hoosmatroos]

And if this is still the original fuel line, consider to replace them completely. Those lines tent to deteriorate over time. And you know it will be good for the next couple of years.

[mike.floutier]

Thanks all, I'll have a look. Hard to spot I guess as, although I could pump some positive pressure with the bulb, fuel is thicker than air so it may be fuel tight BUT not air tight.

[mike.floutier]

Okay well just reading the manual they recommend replacing the fuel line every two years. Can I use any kind of fuel line or should I only use the specific Suzuki parts - presumably pre-shaped?

[Moonlighter]

Mike, i would first do the line from tank to filter and filter to bulb. Thats the most common area for problems. Then See how that goes.

The lines in the engine itself typically last many years, are very good quality from the factory.

[mike.floutier]

Thanks Moonlighter, I'll make that my priority.

It's great to have all this help; really encourages me to learn, try and press on!

[tnadeau]

Make sure the lines are rated for Ethanol fuel even if you’re lucky enough to be able to run non-ethanol fuels.