Frustrating engine problem

[alexanderfoti]

Hi all

My kubota D850 has been running like crap recently.

I have been experimenting with waste veg oil (I run it successfully on my W210 300 Turbo Diesel, 95% filtered and dewatered veg oil and 5% petrol), have advanced the timing 5 degrees and all is well on the 210.

On the diesel bike I first ran 50% diesel and 50% veg and it ran fine.

Went to 100% veg and the problems started. I think it unmasked an existing issue, as it has always been reluctant to cold start.

It runs very rough and the revs go up and down and its generally unrideable at low revs.

Here is a video:

https://www.youtube.com/watch?v=SJ3ZukhqL1M

I have done the following:

[*]New lift pump
[*]New filtration system
[*]All new GP's

The above are all working 100% and its not a supply issue.

I have also

[*]Replaced the injection pump with a refurbished one
[*]Rebuilt the injectors, all pop tested in the same range, with new Monarch nozzles
[*]Carried out valve adjustment
[*]New copper washers on the injectors

Current info shows:

[*]400 PSI on Cylinder 1
[*]360 PSI on Cylinder 2
[*]340 PSI on Cylinder 3

I have figured out that the problem is a misfire on cylinder 1. The looping idle is caused by the governor trying to compensate, then the cylinder firing again and a cycle occurring. Moving the injectors does not change the misfire, it always remains on cylinder 1.

If I disconnect the injector line to number 1 cylinder, I can get it to run properly. See the following video:

https://www.youtube.com/watch?v=nxXERkfoJCw

The above video starts on 2 cylinder, then I tighten the fuel connection to 3.

ANY IDEAS, I am completely out of ideas and getting really frustrated.

[the grinch]

Hi
have you got a filter in the tank attached to the fuel tap the tank may have crud it and now you are on veg oil it may be resticting at the tap.
I had a land rover at work that had been worked on and left due to a fuel problem it would start and run . But when you drove it it would get to a point and misfire but keep running it turned out to be simple. The return banjo bolt had been put in the inlet it has a real small hole that was resticting it.
hope you get it sorted out.
Alex

[alexanderfoti]

I am running it from a test tank with an inline filter, just to eliminate a fuel supply issue

Its a 1L jar with the supply and return lines fed to an electric lift pump, just for testing.

Thanks, so do I!

[alexanderfoti]

At this stage, I am thinking the pre chamber is faulty in some way, possibly cracked, or a valve is leaking.

Going to pull the head I think.

[the grinch]

have you tried heating the oil up it will be thicker than the mixed fuel.
you had good compression on no1?
Put it back on normal fuel and see how it goes first if you still have the problem then i would start investigation again.
alex

[alexanderfoti]

have you tried heating the oil up it will be thicker than the mixed fuel.
you had good compression on no1?
Put it back on normal fuel and see how it goes first if you still have the problem then i would start investigation again.
alex

Yup, same thing.

does the same on 100% diesel, just not as bad. Get lots of intermittent diesel rattle from no1 cylinder at idle.

Yes no1 seems to have the best compression oddly enough.

With good compression, properly adjusted valves, good injector and good injection pump, no leaking of compression form GP/injector, I can only think its the pre chamber, or an issue like that....

[the grinch]

Good luck.
hope you find the problem without to much hassle.
Alex

[coachgeo]

First you'll have to eliminate the WVO system as being at fault to diagnose. Which sounds like you have done partially by running diesel only in it. Next is to remove any possible WVO deposit issues. Run a few cans or four of a diesel injection cleaner thru it. Do an Italian Tune Up as well.

check for air leaks. They are so amazingly good at disguising themselves as other problems.

[alexanderfoti]

Its had a new fuel system on diesel. New injector pump, lift pump and injectors all ran on 100% diesel with the same symptoms.

I am running 2 new rubber fuel lines into my temp fuel container, new jubilee clips. 100% no air leaks.

Something is definitely up with no 1.

[klondikekid]

Just a thought ..and it doesn't cost anything, check valve lash, valve not opening enough/long enough.