[rchad]

I've had a lot of trouble starting my Yanmar 2GM20F lately. I noticed the other day that the primary filter for my Yanmar was only half full of fuel when I was checking the filter. I had topped it off with fresh diesel when the filter was replaced earlier. Why did the fuel level in the filter change? Should the level change? Could air be entering the system somewhere causing my starting woes?

 

[BELLATRIX1965]

Sounds like an air leak!

You are correct in assuming that the primary filter should be totally full!
Sounds like an air leak in the suction line, or since the filter was just changed it is more likely a cut or not properly seated gasket on your primary filter housing. Always go to the last thing that was touched if you start having a problem! Good luck!

 

[rikhall]

I would put money on Bellatrix's answer (not a lot of money - but a little, maybe

It is really easy to pinch the O ring in the filter. We had the same - half full and not running well. It was the O ring on mine.

Good luck

Rik

 

[rchad]

Thanks...I'll get out there and start checking...

 

[L124C]

rchad indicates the motor was "hard starting". Would this motor actually run with a half full separator bowl, since the intake fitting is on top of the separator (at least, on my Racor's)? How would fuel get to the motor? rchad, where was your leak (if you are still around, if not...never mind)?

 

[CaptainForce]

I think the OP is speaking of the spin on cannister primary filter on the engine and not a Raycor or maybe I'm wrong. You'd think that people would consider the "primary" filter as the first filter that the fuel encounters after leaving the fuel tank, but the term seems to be referring to the filter mounted on the engine and not the Raycor. Of course, either way it could be the O-ring and air must be getting in. Take care and joy, Aythya crew

 

[L124C]

I think the OP is speaking of the spin on cannister primary filter on the engine and not a Raycor or maybe I'm wrong. You'd think that people would consider the "primary" filter as the first filter that the fuel encounters after leaving the fuel tank, but the term seems to be referring to the filter mounted on the engine and not the Raycor. Of course, either way it could be the O-ring and air must be getting in. Take care and joy, Aythya crew

Sounds like he was talking about the primary (first to receive fuel) to me. In any event, could the engine run (for more than a half hour) with any filter bowl half full of fuel?

 

[RichH]

Sounds like he was talking about the primary (first to receive fuel) to me. In any event, could the engine run (for more than a half hour) with any filter bowl half full of fuel?

Under the 'right' fluid conditions it 'is' possible.
The 'pleat pack' of pleated filter material flows from outside the pack to inside the pack and if the 'capillarity' of oil being 'held' in the open spaces (statistical 'pores') of the filter material isnt overcome by the motive vacuum of the system .... with AIR on the upstream/outer side being restrained by the filled 'pores' filled with oil, the oil with essentially no air still being 'sucked' though above the fluid level, then it is possible. A lot of 'serendipity' is going to have to combine to do this.

Usually, such a 'coarse' filter material will have a quite low 'bubble point' - the amount of air pressure needed to 'blow out' the fluid from the 'pores' and destroy the capillary action, but under the right conditions of partly dirty filter media, low temperature (higher viscosity) fluid, etc. etc. etc. ... it 'could happen', but not very 'often nor probable'.

That one observes air on the upstream side of a filter ... 99.99999% of the time will be caused by an upstream 'leak problem'.

Vacuum driven filter systems in most 'industrial strength' applications are usually strictly avoided because of their vulnerability to 'air leakage' (along with other very poor 'fluidic effects'). The very BEST way to filter for many many reasons is to use a pressure motive system. On recreational boats, a pressure feed system would require significant increase of component, manufacturing and assembly costs .... and the legal risk (the most important product in the USA, nowadays) to the manufacturer that could possibly cause severe fines by EPA/CG for a design that 'could' wind up delivering small amounts of oil into the water is probably the reason one continues to see archaic and intrinsically flawed vacuum motive systems on recreational boats.