John Deere 6068M85 Marine Engine Fuel Possible Throttle Sensor Problem

[harpoon83]

I am far from an expert, but we have seen codes pop up caused by a low or bad battery. Fuel related, because the electric fuel pump it makes sense that low voltage would trip something fuel related.

 

[Art M]

I’m going to put new wire in tomorrow on sensor. And see what difference it makes. Just cleaning the connections made a huge difference. I’m hoping it will work. Move on from there . The two batteries in boat are brand new glass pack they read 14 amp’s .

 

[Art M]

No change !! I don’t think it’s the motor. When I’m in neutral I can rev the engine 2200 rpm and it purrs like a kitten . When I’m in gear the most rpm I get is 1600 then the engine load gauge hits 100 percent and it starts bucking and farting. I dove under boat prop is clear.

 

[Northern bay]

electronic controls?

 

[Art M]

Checking for fuel line leak next.

 

[Art M]

Would a leak on the return fuel line right at the motor cause the motor to act up? My thinking is it is after the fact. But I’m not sure. Going to fix tomorrow.

 

[Kailua Kid]

I would be surprised if a leak in the fuel return line would cause the symptoms you describe.

Someone on this forum will be able to help diagnose the problem with the codes you provided.

Otherwise, or short of that, my uninformed guess would be a fuel restriction on the intake side (partially obstructed pickup tube, partially obstructed elbow or valve or connection in fuel line, clogged fuel filter) or an air leak into the fuel delivery system upstream of the fuel lift pump (at a joint, connection, filter housing, or in the fuel pickup tube), but this is not in my wheelhouse, as we say.

Let us know what you find.

 

[Art M]

Put white napkins under each injector and took it for a ride . Had one leaking kinda bad and one just a little. Loosen them up . Wiggle the line tighten them back up and took it out again. No leaks at injection. Got to 2000 rpm going good . Thought I had it. I could hear engine start to knock and then it started to hoot and toot. Backed off throttle. And it leveled out got back in again and it would only go to1300 rpm no more .

 

[Art M]

Here’s a question do you think a 2 micron fuel filter in the rancor this time of year could be the problem.

 

[Kailua Kid]

Here’s a question do you think a 2 micron fuel filter in the rancor this time of year could be the problem.

A clean 2 micron filter in the Racor should not cause the symptoms you describe since the flow rating even on the 2 micron filter is higher than the burn rate for your engine at the RPM you are running at, I suspect (but confirm this by reading the specs from Racor/Parker on that filter). Regardless, easy enough to check: Pull out the element and slide in a 10 or 30 micron element and see what happens. And, If you have been running a 2 micron element, I would expect your secondary filter is not obstructed, but of course rule that out by changing it —unless you just did that.

What you describe sounds like an electronic, software driven RPM “get home” limit triggered by a system fault perceived by the ECM on the engine. If that is the case, I will be of no use to you.

BTW, time of year and or ambient temperature should not be relevant to the choice of how many microns you should be filtering to with your primary (Racor) filter. If I am mistaken about this or any of the above, I trust some kind person on this forum will set me straight so you are not led astray.

 

[Genius]

If it was me....not knowing ANYTHING about this particular engine. I would be guessing at an air in fuel situation, I've had it before and the stumbling kinda sounds like it. The black smoke....I can't explain though. Running the engine off a clean jerry can of fuel would be my next step. Do it after the racor (you'd only be utilizing the on engine filter only).

 

[Art M]

Att : Kailua kid electronic software RPM “ get home “ limit sounds like it could be it . Because it happens consistently within 10 to 15 seconds after you go to full throttle. If it was fuel through filter it would happen at different times. Are you able to clear fault codes on your own. And reset computer. Or do I have a real problem where I need outside help with a computer diagnostics reader .

 

[RGT]

I maintained a couple of these set up as gen sets and one thing I found was that running 2 micron racor filters if there was any increase on the vacuum gauge on the racor I would see the fuel pump pressure on the engine drop. If I let the Racor run into the yellow range I would see the displayed fuel pressure on the engine drop from the normal 6-7psi to 3-4 psi, so once I saw that I always changed the racors as soon as the needle budged on the racor. I suggested they change to 10 M filters on the racors but left the job so don't know if they did.....

 

[Downrigga]

I would increase the 2 micron to a 10 regardless. There is much more fuel trying to get through that element than just the burn fuel. The return fuel adds up.

 

[Genius]

Yup 2 micron in primary (racor) is bad news. Ran a boat like this(owner bought 2 microns) it only lasted 2 days on a filter.

Should have a vacuum gauge on your Racor anyway. This would tell you immediately.

 

[ssevenjohn]

i have a Deere 6068 SFM 50,little different, and was told to use 20 or 30 micron filter...no less. for what its worth.

 

[andy65]

Here’s a question do you think a 2 micron fuel filter in the rancor this time of year could be the problem.

The John Deere manual specifies 10 micron for the primary fuel filter (on the engine) and 2 micron for the secondary. It makes no sense to have a 2 micron Racor ahead of a 10 micron on the engine. It may not be your problem, but it should be changed. It could also be a contributing factor. Also check that the engine filters are per manual.

Note that in the filter world, a 10 micron filter doesn’t get all 10 micron particles. It gets something like 97% or whatever. A second 10 micron get 97% of the remaining. So a 10 Racor and a 10 primary is useful.

 

[Genius]

No such thing as 20 micron. Primary filter is typically described as the first (racor). The secondary filter is typically the second or final filer (on the engine). Port is left side of boat, starboard is the right side

 

[andy65]

Primary filter is typically described as the first (racor). The secondary filter is typically the second or final filer (on the engine).

You are correct in general. The key word is typically. The John Deere 6068 has 2 filters mounted on the engine and labels them as primary and secondary, D and A below. The manual gives no guidance on Racor size that I have found.

 

[Genius]

I notice the primary filter in that picture shows a water drain. That is typical with a primary.

Which way is the flow in the picture? It’s not obvious to me.