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CATEGORY LISTINGS > JOHN DEERE > John Deere 3125 AFM

Thread Title: John Deere 3125 AFM
Created On Sunday June 14, 2009 09:56

John Deere 3125 AFM

John Deere 3125 AFM

John Deere 3125 AFM

John Deere 3125 AFM

John Deere 3125 AFM

Posts: 3
Joined: Jun 2009

Sunday June 14, 2009 09:56

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This is an engine on a commercial fishing boat in Alaska.It has a little over 8000 hours on it.It was new in 2003.Yesterday we got in after a fishing trip and had just tied up at the cannery when an alarm from the engine guages panel went off.It was an amber lite with the alarm and after reading the engine manual we finally figured out how to get the service codes from the lcd guage. It said SPN 1569, FMI 31 this is "fuel derate" according to manual. The other code was SPN 94, FMI 18 this is " fuel supply pressure moderately low" according to manual.I use a 10 micron Racor filter as a primary filter and then whatever the John Deere filter on the engine is as far as microns.Those two filters were changed less than 500 hours ago and this last trip the fuel pressure seemed to be in the good range ( 67-71 ps) even on the way home which was only 15 hour run.Not once did the engine sound different.I will change filters and see what happens but my concern is that something else might be going on.This is the first alarm or problem on this engine ever.Im about to fish salmon for 2 months so hopefully this is a filter issue.Also does anyone have any advice about this engine as far as what the future holds in problems and what spare parts we should have on board?Thanx everyone!

Posts: 404
Joined: Dec 2008

Monday June 15, 2009 15:59

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Sorry to say, but the fuel available these days is not what it was. We see people changing the fuel filters about twice as often as before and also we have had much more pump failure in the last few years. The JD engine seems to handle it much better than Cummins, so you have that going for you. I would change the filters and give it a full bore test run before you head out on a long trip.

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One of the last 2 Stroke mechanics left.
40 years in the business and worked on everything from 53 series to 149 series.

Posts: 3
Joined: Jun 2009

Tuesday June 16, 2009 20:48

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Thanx for reply.I changed filters and no alarm so far.Its funny,,,never had this problem before and never have gotten bad fuel from our only fuel dock.I change fuel filters religiously especially before going out into the ocean and thats why Im kinda waiting for the other shoe to drop.I hope it was that simple.

Posts: 3
Joined: Jun 2009

Sunday June 28, 2009 19:43

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Well it wasn't that simple.I changed out the fuel pressure sensor and that didn't work.The alarm is going off again.I made my first salmon trip of the season and found out running the engine at 1400 rpm's I have lost about 9 psi +/- on fuel pressure.This is on freshly changed primary and secondary filters.Usually at 1400 rpm the pressure is 68-71 psi now it is 61.Thinking is now its the pump so another one is on the way.Will let you know.

Posts: 3
Joined: May 2010

Tuesday May 11, 2010 09:11

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6125 had issues with the pressure regulating valve in the filter housing. It's located right under the pressure sender in the back. It's cheap and easier to buy a whole housing with the senders, filter, and relief valves already in it.

However, I agree the fuel is the first thing to blame. It doesn't have to be text book bad to cause problems these days.

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