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rperret 05-21-2007 03:17 PM

Yanmar - fuel injection pump question

Have a 2004 1GM10. Just purchased boat and don't have a lot of specific experience with this motor. Has been hard to start cold - when I apply lots of throttle she'll start up. When engine is warm - she starts instantly.

Noticed strong diesel fuel smell yesterday, found diesel fuel on motor. Today, on closer inspection - and after trying to start 3X - i saw fuel and air bubbles ooze out under the banjo bolt - the fuel/air bubbles were coming out from the washer between the block and banjo bolt.

Appreciate any tips on replacing the bolt and washer - assume need to be careful not to bend the fuel line when replacing.

Also - the manual is not very clear on how to bleed the system. When i try the manual lift pump - i pump up and down - practically no resistance and when I opened up one of the bleed screws - no fuel was coming out. I understand that you need to turn the engine so the cam is against the pump lever so it works - since I don't have a manual hand crank for the motor, what is the easiest way to turn the cam?


welshwind 05-21-2007 03:31 PM

Two things from my experiences with a 3GM30F:

1) I was told by a Yanmar mechanic the correct way to start the engine is at full throttle and then quickly rachet back once it fires off.

2) I have never had any luck with the manual pump lift. Some people have said to manually turn the crankshaft a bit and it should engage. Never had it work for me. The only way I can bleed is to be in the engine compartment with my screwdriver ready to close the bleeding screw and have someone fire up the engine. I tuck a little paper towel around things and it really doesn't get too messy.

Don't know anything else about the other items you asked about.

billangiep 05-21-2007 05:49 PM

I also have never had any luck with the manual lift pumps, what I did is install an outboard primer bulb in the fuel line before the the filters. also you can re-quench the copper washers by heating to a cherry red with a propane torch then submerging in water. Yanmar link.....BLEEDING AIR

mwrohde 05-22-2007 08:05 AM

I've got a much older 1GM. The manual pump works fine for me. It has a short throw and can take a lot of pumping. I recently replaced my fuel separator cartridge and I'll bet it took 5 minutes or more to finally get fuel at the first bleed screw.

petegingras 05-22-2007 08:20 AM

Yep, the outboard primer bulb in the fuel line before the the stage one filter is my advice. Used this on my Yanmar 2QM and wouldn't hessiate to install one my current yanmar.

I bled my 2QM a half dozen times one season after taking on bad fuel, the bulb was a suggetion from a non-boater and it's cheap. Good luck.

rperret 05-22-2007 03:35 PM

Thanks all. Will have fun tomorrow nite doing the banjo plug removal. Just picked up the part - it looks simple, and I hope the old one comes out easily.

Re the lift pump - didn't realize you have to pump for a long time - i only pumped for all of 1 minute....obviously not enough time...

Re bulb before primary - i like that idea, and maybe can help to get rid of old/bad fuel too.

mwrohde 05-23-2007 07:17 AM

Just bleeding the line for a fuel leak doesn't take long (or hasn't for me). That has been as little as 5 - 10 pumps.

Priming after replacing the cartridge in the fuel/water separator did because that little pump had to fill the bowl of that separator. Lot of pumps for that much volume of fuel.

Also, you should feel two "stages" in the pump. The first part of the throw has very little resistance. Then you will have a second part that resists a little more. Push the lever through both stages on each pump.

rperret 05-24-2007 10:00 AM

project complete
Old banjo bolt removed easily - and seated new bolt without any problem.

Surprisingly the bleed was easy - 5 pumps and fuel was flowing from the first bleed screw - then got lots of air out of the injection pump screw.

Motor started on first crank in 3 seconds.

Current problem solved....impeller is next

MackBoring reps stated to ensure that one doesn't over tighten bleed screw - most people do which causes problems down the road.


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