Odd injection/combustion noise.

[alexanderfoti]

After my sediment issue and a replacement fuel pump I am back on the road.

However I have an odd issue.

I ran some millers injector cleaner and some diesel in a 70/30 dilution from a small bottle through the system before plumbing back the main fuel pipes.

Mainly to get rid off any crap that may be in the injector lines.

Whilst I was running it through, it had some very pronounced diesel knock, much louder than usual. No that I am running on my normal blend, I still have the same loud knocking noise, maybe a bit quieter.

I had already advanced the injection timing for veg slightly.

I understood that injector knock is good, and indicates the combustion is occurring st the right time.

Any thoughts?

[coachgeo]

??? screw driver or garden hose piece to the ear as a stethoscope to try to determine if it is a combustion knock or rod orr at least what cylinder the knock is on the most???

If once cyclinder seems to be the knock then move your injectors and see if knock follows the injector?

Run another batch or two of cleaner thru? Maybe you dislodged something with the cleaner but it only moved it to a new place?

[alexanderfoti]

It's definitely combustion knock. It matches the throttle position.

Only one cylinder as well so it can only be one injector.

Thinking about it I put the rest of the cleaner in the tank, so it's probably that making the noise! When have run through the tank I will see if it still makes the noise

[coachgeo]

If you need too....(repeat of a system recommended to me years ago)..... get some aluminium pie pans. One for each injector. Some Carb/parts cleaner---- the type intended to run in an engine parts cleaning bin. It comes in a paint can usually. Also a can of spray carb cleaner too so you the oomph of the spray can available to you as well. Take each injector completely apart IN IT's OWN pie pan. DO NOT MIX PARTS. Record well how the injector came apart, order of spacers/disc or?? within the injector etc. so you can reassemble correctly. Soak the injector parts for days in the cleaner. Shoot at it's ports with the can and all it's openings. PROTECT YOUR FACE etc. from splash back. Reassemble and install.

Oh........ and do it in as much of a "clean room" environment as you can. That is one reason why it cost surprisingly a bit much to have injectors rebuilt........ supposedly they are done in a true clean room so no tiny dust makes it into tiny injector holes etc.

[alexanderfoti]

Many thanks CoachGeo!

All sorted now though, sorry I didnt read your message before I ran off to fix it.

A new fuel pump has sorted it, there must have been something wrong with the replacement pump.

I also ultrasonically cleaned the injector tip, I didnt dismantle the whole thing though. However, even before I cleaned it, the spray pattern looked OK.

Some pics

before:




during cleaning:



after:

[coachgeo]

....
A new fuel pump has sorted it, there must have been something wrong with the replacement pump. ....]

Glade you got it fixed!! With that in mind did you replace the "fuel from tank to engine" pump or the fuel "injection" pump. Different regions call things different; but similar names, thus just curious which one you switched out and what made you suspect it.

[alexanderfoti]

It was the injection pump, rather than the lift pump.

I had a breakdown recently due to the injection pump sucking in some sediement and failing.

It was the last replaced part so I suspected it for that reason only