I am have been trying to bleed the fuel lines for a Yanmar diesel engine (model 30GM30F) for 3 days now...How many manual pumps does it take to get fuel coming out of the fuel pump bleeding screw??????
A bit of recent history:
I changed the primary filter (Racor) and then primed it by toping it off with fuel.
I changed the secondary fuel pump filter (but did not fill it with fuel, as I just read earlier in another thread).
The first time I used the manual lever on the lift pump I did not know what kind of "pressure" I was supposed to feel, but nothing (no air bubbles nor fuel) was coming out of the bleeding screws. I had not read at that point that I should turn the engine a half turn (by manually moving the belt) in order for the pump to have pressure and be able to actually pump. So, to see if the lift pump was working, I disconnected both the intake and the outtake hoses (of course letting yet more air into the fuel lines, I now realize).
So, once I realized the error of my ways, I made sure all connections were back on and secure and started pumping while cracking the fuel pump bleeding screw. After quite awhile pumping I did get air bubbles, then nothing, then more air bubbles, then nothing. I did the same thing with the bleeding screw on the fuel injector pump and got the same results. However, I have not been able to get fuel flowing without air bubbles as I read I should. The first time I bleed the screws I did have fuel with bubbles but now I see only air bubbles or nothing. At one point the fuel intake handle coming in from the fuel tank was closed off, but I reopened it and have pumped for a long time.
My patience is really running thin. How much do I need to keep pumping? Is the lift pump no longer working though I feel pressure on it? If I disconnect all the fuel lines to make sure there is no blockage then how in the world will I bleed that much air out?
I'd love to hear from anyone with some suggestions.