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Nanni Diesel problems - Fuel Filters


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The engine cranks but won't start. It happened rather suddenly. It's a Nanni 15, 2 cylinder 2-60he

Does anyone know if the glow plugs run off the starter battery or off the house battery. I'm not on the boat now and didn't think about that until I got back to shore. A friend helped me spray ether into the air inlet but that didn't help the firing.

I thought I'd replace the fuel filters to see if that helps, but I could be on the wrong track.

We just discovered there are two fuel filters, one on the intake side and one on the overflow to take fuel back to the tank. But the intake one (see picture) appears to have a screw on glass at the bottom. I haven't fiddled with it because I want to know what I should do first.

Any tips would be appreciated both on the failure to start and on the fuel filters.

Would diesel bug cause these problems?

nannidieselEngine.jpg

topNanniDieselFilter.jpg

UnderneathNanniDieselFilter.jpg

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Im no expert but mucked around on a few diesels.

I guess the first thing to check is if there is diesel actually getting to the engine. Could be a blocked filter or Air in the system but normally it would be a gradual fuel starvation and slow loss of power rather than an abrubt stop.

The 2 fuel filters should be both on the intake side, a primary and a secondary.  primary being combined with a water trap and then the secondary being a much finer filter.

When were the filters last replaced? That oil filter looks like its been there a while...

Normally these would be done every year along with the oil change.

 

 

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Wow. Thanks for that. I thought I traced the second one (the one close to the engine block) back to the fuel tank. But I could be wrong. My friend said a return was common but he's no great expert.

Yes they need replacing.

How should I check that fuel is getting through?

My friend said it might be the injectors too.

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48 minutes ago, Kevin McCready said:

If it's a water trap. How can I check there's not too much water? Or what happens to the water which is trapped?

open the tap or plug on the bottom (carefully with a container underneath)  you should be getting diesel out, there should be NO water.

Fund the fuel pump, there should be a bleed screw (or bolt) that you can loosen and then manual operate the fuel pump (lever on it) and make sure you have clean diesel pumping through i.e. no air.  Of there is air keep pumping.

Is your refrigeration turned off? maybe the compressor is putting more load on and not getting enough revs to kick over? 

Good luck

 

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Crack the fuel line at injector and crank motor,if fuel there should start,if no fuel it will bleeding ,think the govner has a release screw on it,crack turn motor over till fuel appears. close while stil cranking to avoid sucking air back.

When did it last run as battery may turn engine over but not quick enough to cause compression of fuel at injector,comes out as a fine spray.but you wont see it unless taken injectors out for testing.

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Hi Kevin

Grant is correct - the primary filter mounted to the bulkhead is also a water separator.  Water gathers at the bottom of hte glass bowl - there shouldn't be any.  Drain it to find out.

The secondary filter housing apperars ot have a bleed bolt on top of it - middle front above the letter S in the word diesel on the filter.  If you open this slightly while cranking the engine, diesel should come out steadily - if there is air in it, the stream will bubble.  If there is air, keep going until it stops bubbling, then tinghten the bolt down.

After that, follow Harry's directions to bleed any air from the injector pump and governor.

Diesels are very simple engines - if they turn over and have clean fuel they will generally run (short of a catastrophic failure internally)

 

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When Harry says "crack the fuel line" what he means is slightly slacken the union the holds the fuel line to the injector ("cracking" the nut).  You do not have to remove it completely, just loosen it.  When you are cranking hte motor over, with the line cracked, you should see pulses of clean diesel spurting from the union - again, it it bubbles thats air, keep cranking until it stops bubbling and then tighten the union solidly.

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At the top of the engine you can see two rigid steel pipes that carry fuel from the injector pump/governor to the injectors.  In your picture above, these pipes disappear behind stuff downward on the lhs (as we are seeing the engine in the picture).  The end of the pipes we can't see are attached ot the injector pump/governor.

On that device there will be a bleed screw - it will be a smallish bolt, possibly it will appear to be drilled down its centre, and it will be located near the top of the injector pump/governor.  Loosening it slightly and cranking the engine will result in the same stream of diesel you saw coming from the bleed screw on ther secondary filter housing.  Again, if you see air, keep cranking until you do not.

 

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If it would really would not fire at all on engine start- you have eliminated the fuel system.  If you are sure it won’t fire on engine start, then it has no compression .   Start looking at the decompression stop system….  or it’s had a catastrophic failure.

 

 

 

 

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Be careful you don't crank so much that you hydro lock the engine. 

I would suggest closing the raw water inlet till you get it started and have a spare impellor at the ready (ideally remove the impellor) to much cranking and you're going to be in a world of pain... 

It would be exceptionally unlikely for the glow plugs to be on the house battery...

 

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If you had a gradual loss of revs/thrust  I would check the exhaust elbow for blockage.If completely blocked  you will also see a carbon buildup in the cylinders with unburned diesel  resulting in  no combustion.

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Success! Thanks. I want to thank each and every one of you.

Here's what I did with my wife's help. And some interesting things happened.

1. drained about 50 mls fluid from the primary filter and it seemed to be diesel

2. loosed the blue bolt on top of the secondary filter and cranked it and then tightened again (didn't see any bubbles)

3. Took off the black plastic box (which I think is the air intake but I'm not sure). Pic attached - the black box came off where the two bronze looking large hose clips are at the bottom left of the pic. Strangely the box seemed to be empty. Is it meant to have a filter in it?

4. Sprayed ether mix (Start Ya Bastard) into the hole for 2 or 3 seconds and tried to start

5. It ran for a few strokes and stopped. Repeated 4 about 5 times and each time it ran for a few strokes and stopped. So I pulled the bar on a spring a few times with the rubber concertina boot secured by the silver keyring thing. I thought it might be the manual fuel pump, but perhaps the manual fuel pump is the little blue leaf-like thing so I pressed that up and down a couple of times too; it's at the very bottom right of the picture with the keyring.

6. It STARTED and ran for three minutes and then slowed down - my wife and I both heard it and thought - uh oh.

7. I put the revs up in neutral for 10 mins

8. Put it into forward and it didn't like it - slowing down to almost stall

9. Put it into reverse and it clunked to a stop.

10. Oh god I thought, the propeller or drive shaft has seized.

11. started again without ether. started first time

12. Ran it at high revs in neutral for a minute

13. put it into forward again and it slowed but didn't stop. I let it labour a bit and then into reverse and it didn't stall but slowed to almost stalling

14. repeated 13 a few times

15. Then (perhaps 15 minutes after start up) it went into gear without complaining

16. Run it hard in gear for a minute and heaps of smoke came out for a bit and then smoke stopped. I ran it under moderate load for a few minutes in reverse without problems.

So I'm guessing there was some sort of blockage stopping it from accepting the load of the propellor. Maybe it had water stuck inside as someone warned.

I couldn't find the governor screw.

 

nanni diesel black concertina boot QQ 20220327_174017.jpg

nanni diesel air intake box removed 20220327_173859.jpg

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Hi Kevin - congratulations!!!

Not bad for an old guy with a dicky ticker.

1 - yes there should be an air filter.  

2 - the "bar on a spring" looks to be the engine speed control.  Technically known as the Rack.

3 - looking at the fuel lines your set up appears to be capable of self-bleeding.  The inlet to the pump/governor has two line attached - one from the secondary filter, and another that looks like it returns to the tank.  Its possible that you got air in the system and just gave up a bit too soon earlier in the day.

4 - it will take the engine a while to warm up and accept a load.  If the fuel is old and the engine hasn't run for a while its not unusual for them to stall at idle.  MArine engines are set up to run at constant speed DESPITE load, thats why the have a governor on the pressure pump.  If the engine hasn't run for a little while its entirely possible the governor has gummed up a bit and needs a bit of encouragement to start playing the game.  Your comment about it smoking for a while under load before clearing supports this theory.

5 - you couldn't find the governor bleed screw because it doesn't appear to have one - hence my belief that it is set up to self-bleed (comment 3)

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Thanks Ashton! So it seems the guy who sold me the fuel filter might have been right after all. He said just whack it in after you've filled it with fuel and shouldn't need to bleed. I'll take the black box back to him and ask. But I couldn't see how you could get a filter into it. Maybe the whole plastic shebang needs to be replaced.

 

I also discovered that the solar panel seems to only keep the starter battery topped up. The house things came back to life after the engine ran for a bit. I'll have to chase it up.

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something looks a bit strange with the engine mounted filter.

Where does the braided line on the inlet side originate? Should be from the lift pump.

The outlet side appears to be connected to the injector fuel return?

The filter outlet should be feeding the injector pump, the fuel return line should be going back to the fuel tank.

Where is the injector pump getting its fuel from? 

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