ISX Fuel Actuator

[bsiddle]

Afternoon everyone,

I run into a problem that I'm having no luck figuring out.

I have an ISX 871 that idles very rough. I know this because I have the same (same year model, year) motor in another truck.

So far I've checked all hose connections, changed the fuel shutoff value and changed, filters several times (been doing this for a while).

I started unplugging each actuator, one by one, and noticed a change in sound. It actually idled better with one unplugged than all plugged in.

Occasionally, the fuel delivery pressure light will come on, but it usually goes off within seconds. It does this even with the tanks completely full of fuel, so don't think it's a pickup tube. It also doesn't lack power, so I haven't changed any hoses. But, it will belo black smoke when you get into it hard.

Any thoughts?

[Waterloo]

How many miles on the truck? What model, etc...

[bsiddle]

The truck is a 2009, 386. It has 750K miles, but had a new head and injectors at about 630K miles.

[Waterloo]

Well, 800,000 or there about is said to be the lifespan on these fuel actuators... There is a video here on how to determine if they are bad. When did the problem start? After the work? And on a side note, Cummins manufactured quite a few bad injectors not that long ago, around the end of 2015, that is when the list was published... That info with part numbers was published here, they had a silent recall... I printed it off and took to my dealer that did my in frame, during the in frame, to double check I was not getting any of these defective injectors.

Or possibly a lift pump? I had mine replaced, but remember the mechanic stating they fail at around the same time those actuators do... I had him replace everything.

I'm dumb as a post with this stuff, hopefully someone will chime in... Do you have any codes? That will possibly point us in the right direction.

Do you still have the mandate?

[Brock]

If you read rawzes actuator writeup under technical documents and have any mechanical skill at all, for the price if a dial indicator and some brake clean you can test and clean your actuators. reinstall once cleaned and see if it runs better. cheap ad borscht diagnosis.

Then if you wanna spend a couple hundred you can get the injector test plate from Cummins.

I would pop the valve cover for free and check loose injector wires before bringing it to a mechanic I'm paying. it's all cheap compared to his bill.

As waterloo said, maybe someone smarter will chime in

[bsiddle]

Thanks for the reply.

The mandate is still there. I changed the cooler and did a tune up a few months back.

I have no codes, just the low fuel delivery pressure light that goes on and off. But the idle stays the same rather the light is on or off.

I did a country boy check on the lift pump (took the return line off and made sure it was pushing fuel through the system with the key on and motor off). It was working, and was running the full 2 minutes, but don't know the pressures.

The head and injectors were replaced by the dealer I bought it from. When I looked at the truck it was blowing air in the radiator so they changed it. I forgot to list earlier that they also changed the cam bushings at the same time.

It's always idled rougher than the other one (I bought two sisters Vin ending in 475 and 478. The two are identical, same motor, trans, everthing).

The part that throws me off is it actually idles better when I unplug one of the actuators. It does matter which one, timing or metering. I realize that it wouldn't run that way, but seems like it should idle worse (?). It's thrown me for a loop, and I know if I bring it to a shop they'll want to change pumps and ecm and everything else. Its change parts until it gets better around here.

[bsiddle]

Thanks Brock!

I'll try to find the write-up on the actuators. Usually, if I take it apart I can get it back together, but by no means am I a mechanic.

I can also check the wiring on the injectors. I didn't think of that. The truck I drive still has a mechanical motor, not use to all the sensors and stuff.

[in2trux]

Which actuator did you unplug that smoothed it out? Do you have insite?
All new actuatorsis are about 2 large.

You could start by checking them for wear to find the culprit.

[bsiddle]

I can unplug the timing and the meter on the back set and it idles better.

Insite? I'm not sure what you're referring to?

I priced them today, $460 a piece at Cummins.