Yanmar SB8...Lift pump or leak or blockage???

B

braol

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Apr 16, 2014
348
Hunter 27 Rebel 16 Great Lakes Naval Base, IL
The other day I got a good amount of stuff done (although not as much as I thought I should have):
-Mast step and halyard base plate installed.
-New raw water intake through-hull installed.
-New sink drain through-hull almost finished...
-Engine put back together and attempted test run...

...everything was going swimmingly, bled the lines, new diesel in the tank, new filters all around, and then crank, crank, crank, crank...nothing. So I figured I'd just bleed the lines again in-case there was still air in there, only this time no fuel came out at all. Crank, crank, crank...engine decompressed, starter spinning nicely, still no fuel. Either I have a massive amount of air in there after the filter change, massive air leak, a big fuel line block, or the lift pump is shot.

I'm going to bypass the tank and water seperator and run a fuel line directly out of my 1-gallon diesel can to see if I'm getting suction at the pump. If I am then there is a leak or blockage somewhere...if not then I'll have to go electric auxillary fuel pump because I can't find a replacment Yanmar SB8-engine lift pump to save my life.
 
kloudie1

kloudie1

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Nov 6, 2006
9,893
Hunter 34 Mandeville Louisiana
Probably massive air problem.. In replacing filters, Did you fill them with diesel first?.. part B: in using the lift pump finger lever, make sure you are getting a full stroke. sometimes you have to manually rotate the engine a quarter turn or a half turn or more to get the internal cam off the actuating lever which lets you move the lever through a full stroke. Good Luck !
 
B

braol

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Apr 16, 2014
348
Hunter 27 Rebel 16 Great Lakes Naval Base, IL
It seems that my engine does not have a lift pump lever. Just the pump sticking out the side of the engine.

I successfully got diesel (fresh) to exit out of the pump bleed screw and out the injector bleed screw, so it seems that I did, indeed, have air in the system upstream of the lift pump. This also confirms that the lift pump itself does work, so at least I can eliminate one item from the inop list.

After verifying that I have fuel being pumped to the injector, I pulled the injector but could not get fuel to come out of it while cranking (although I could blow air through it, strange). I also could not get any fuel to come out of the return line, downstream of the injector.
 
C

Canyonkeeper

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Jul 21, 2014
61
Hunter 27 Cherubini Lanoka Harbor
Had the exact same problem. Ended up cracking upen every line 3+ times one at a time then cranking. Took about a hour. The filter on the engine is the weak link. Need to fill that with a cup a diesel several times.
 
B

braol

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Apr 16, 2014
348
Hunter 27 Rebel 16 Great Lakes Naval Base, IL
Canyonkeeper said:
Had the exact same problem. Ended up cracking upen every line 3+ times one at a time then cranking. Took about a hour. The filter on the engine is the weak link. Need to fill that with a cup a diesel several times.
Click to expand
Any tips on bleeding the return line? I don't seem to be getting any fuel through this line. Also, Do you have a manual pump lever on your lift pump???
 
B

braol

.
Apr 16, 2014
348
Hunter 27 Rebel 16 Great Lakes Naval Base, IL
I'm picking up a vice today at the local big-box store so. i need to get some leverage on my injector so that I can take it apart and clean it. Stay tuned.

PS Does the SB8 have an additional high-pressure fuel pump or is the lift pump the only thing? It appears that the fuel lines go tank to fine-filter to lift pump and then direct to injector...
 
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