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671n hard to start

D

denis_k

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I have twin 671n's in my b

I have twin 671n's in my boat if I don't use it for couple of days it takes a lot of cranking to get it going or if i push throttle open to about 30% it will start but at about 1000 rpms any suggestions or help? THANK YOU
 
"check fuel hose,s for eny lea

"check fuel hose,s for eny leaks or wettnes around fitting.befor starting next try primeing fuel sysem to see if that helps."
 
"If you have to prime the fuel

"If you have to prime the fuel system to get it to start, consider installing a check-valve on the fuel supply piping just before it goes to the primary fuel filter.

Do you have to prime the fuel system every time to get it to fire up correctly?"
 
"DID IT HELP WHEN YOU PRIMED S

"DID IT HELP WHEN YOU PRIMED SYSTEM,???DID YOU ISTALL CHECK VALVE BEFOR GOING INTO PRIMARY FILTER??."
 
"if i prime the system it star

"if i prime the system it starts with out pushing the throttle open, but it still takes some cranking not as much as before. Also it stars and shuts of after couple of seconds and after reapiting 5 or 6 times it starts and runs with no problems."
 
"try primeing intill you here

"try primeing intill you here fuel comeing back into tank,also open throttle a little"
 
If i open throttle a little i

If i open throttle a little it will start and rpm will fluctuate for about 30 seconds from 600 to 1000 if i bring throttle back before the rpms stop to fluctuate the engine stops running.
 
The reason for installing a ch

The reason for installing a check valve before the primary fuel filter is to keep fuel in the engine from draining back into the fuel tank. Installing a check-valve JUST on the return side will do no good if fuel is still draining backwards through the supply piping back into the fuel tank.

Are your engines equipped with a hydraulic or mechanical governor?
 
I belive the engines equipped

I belive the engines equipped with mechanical governor.
One more question can the bad injector cause the problem?
 
"If this is what your governor

"If this is what your governor looks like, then it is mechanical.

http://www.marineengine.com/discus/messages/12495/221120.png"" alt="""">


In regards to the RPM fluctuating, a bad injector most likely won't cause that to happen.

To correct the fluctuation, I would start by checking the gap in the picture that I have a red circle around. The gap should be .006" Pull the governor top off and you will find what I am talking about. If the gap is correct, the next step I would take would be to pull the governor drive off the blower and check for bearing wear in the drive. (Please forgive me if I am wrong, it's been awhile since I've worked on a mechanical governor)

[img]http://www.marineengine.com/discus/messages/12495/221121.jpg

On a side note, if an injector goes bad, most of the time it will cause the engine to white smoke out of the exhaust, or the injector will stick. If it's stuck, the plunger will stay all the way compressed, or (if you have an old-style rack) it won't let the rack move.

Let us know how it turns out."
 
Just to add a little on the ch

Just to add a little on the check valve. If you have a Racor filter as a primary filter it has an internal check valve. So noe need to ad another to the system. I have seen these valves stick open or have a damaged seat. If it is stuck open the fuel will flow back to the tank when shut down if the tank is lower than the Racor. A rebuild kit is available that comes with a new check valve and valve seat. I had the same problem on one engine in a set of (4) 12-71's.
 
"Well i have one of the engine

"Well i have one of the engines runnig right,but my port still giving me hard time and that's the engine with no leaks, no oil consumption and by the book oil pressure. Yesterday morning was cold and i used starting fluid and it fired right up. Any ideas and should i just crank it longer instead of using the starting fluid?"
 
"Start by checking to make sur

"Start by checking to make sure your battery is fully charged. You can also check your fuel rack settings and injector height. Try not to start it too often on starting fluid, as it can become addicted. If it becomes an "ether-baby" it won't start unless you use starting fluid no matter what you do. Of course, starting it like that every now and then won't hurt anything. Just don't make it a habit."
 
"Thank you for the info Jimmy.

"Thank you for the info Jimmy. One of my friends told me also if i have a slick out of my exaust when i first start the boat i may have a bad injector have you heard anything like that before? Because on my port side i do get some discharge out of the exaust and some white smoke on the start up, but it goes away in couple of minutes."
 
"Is the "slick" like o

"Is the "slick" like oil? Most of the time, if an injector goes bad, it will white smoke all of the time because the tip has blown off and it's constantly pouring fuel into the cylinder. So that would cause a slick out of your exhaust.

I've always found that if the white smoke burns your eyes when you stand in the cloud of it, then it's diesel and you should check your injectors.

If you want to check your injectors anyway, an easy look, after the engine has set for a while, maybe overnight, is to pull your inspection covers off and roll the engine over by hand and look for diesel on top of the pistons.

It still wouldn't be a bad idea to check your valve clearance (.016) your injector height (1.460 if it has N55 injectors) and your rack."
 
What should I check for on the

What should I check for on the rack because that engine will smoke only for about 5 min or so as soon as temp goes to about 110F smoke goes away and one more question does the injector size makes a diference for the valve clearance?
 
"When the rack moves to the fu

"When the rack moves to the full fuel position (all the way towards the injector) you should be able to move each injector clevis...Where the clevis wraps around the ball, you should be able to move the clevis up and down with a screwdriver.

You also want to check when it's in the full fuel position that each clevise is pushed in the same distance. You shouldn't be able to move one clevise in very far by itself. It's really hard to describe what to feel for, so I apologize if my description is vague.

Injector size makes a difference in the Injector height setting..it makes no difference in the valve/rocker arm clearance.

If your engine only smokes for 5 mins or so, and as long as it still has good power and normal fuel economy, I don't think you have to worry about it causing any damage.

Does your STBD engine smoke on start-up?"
 
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