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Discussion Starter · #1 ·
Well guys still having problems with the remanufactured motor. We put in the M25xp and Martec made a 16"x16 rh prop for the boat and 2 other prop makers confirmed that would be the prop for the boat, put the boat in the water could only get about 2100 rpms and 5.o knots. so figured the prop was wrong and martec stood by there prop and made a 16"x12p rh, pulled the boat and swaped the props to find that the motor still only would hit 2100 rpms and not only go 4 knots, so now we know its not the prop. my thinking is something is up the the motor what do you guys think? motor revs up just fine when not in gear 3200+ with ease. Any ideas I am trying to locate a good diesel mechanic to look at the motor. Thanks

Scott
 

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I'm betting your engine is fuel starved. Doesn't take much fuel to run an unloaded diesel; takes a lot more to run it hard under a load.
Your diesel mechanic will probably be able to fix it by fixing the injector pump, probably by adjusting it.

If it puts out black smoke when he finally gets it up to speed, that'll be excess fuel and he'll adjust it back down.

Blue smoke; oil. Black smoke; fuel.
 

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Discussion Starter · #5 · (Edited)
Here is our fuel system setup. we have a 29 gallon tank that is in the cabin under a seat about the same height as the motor and about 10-12 feet away. The motor has a mechanical fuel pump on it, so with the long distance and no gravity feed to help we added a electric Facet fuel pump 4 psi just before the racor water seperator filter. from the racor filter to the fuel filter mounted on the motor and from there to the mechanical pump / injector pump. I just pulled the vent line and blew on it and it blows freely. I get return fuel from the last injector but its not streaming out just trickling. how would one adjust the amount of fuel on the injector pump. thanks guys.

On a prop note, I can only assume a less pitch prop would be easier to spin than a higher pitch prop since it not pushing as much water. the prop builder said that you should gain around 200 rpms per 2 pitch that you go down. and we saw nothing, exact same rpm and just less speed.

Thanks for all help and advice. Scott
 

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Check to be sure you throttle cable is operating properly at wide open. It sound like you just are not opening the throttle fully.
 

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...........how would one adjust the amount of fuel on the injector pump. thanks guys.........
The procedure is detailed in the manual - not the operator's manual, the mechanics manual.
On my Yanmar it consisted of placing or removing shims within the injector assembly. Seems like injector timing and fuel amounts were adjusted the same way.....it'll take a mechanic either way.
 
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