The rpm bouncing is similar to what mine does when you push the clutch in and coast too an idle. I'm assuming it's the FCA (Arson kit) and rail pressure bleeding off. I think yours is a bad lift pump because once you get it started the cp3 can pull fuel through a lift pump if it's in the open position

 

Got the Ultra-Gauge today. At cruise, pressure stays steady, anywhere from 16-20k depending on throttle position. When I clutch in, and the idle does the seesaw thing, the pressure drops to around 5900-6000 before settling back in the 6800-8000 range, which is where it is when it's stable.

FWIW, since yesterday, the starting issue is virtually gone. It still stumbles ever so slightly on the first two revolutions but then it fires up just fine.

Rob

 

It should be idling around 6K psi on a warm engine. Watch it for a while, and especially when it starts to run rough again.

 

Thanks, I'll keep an eye on it. I have to go to Portland tomorrow night so I'll have lots of time to monitor it.

Oh -- the gauge also kept warning me about a high voltage condition. It'd tell me it was seeing 14.94 to 15.0v.

Rob

 

That is normal on these trucks with a cold battery, you need to either disable or raise the voltage alarm.

 

How do you disable it? The thing didn't really come with instructions. It's fairly self-explanatory, somewhat. I'm gonna go out and play with it here in a bit and see if I can figure that out, and setup a custom gauge page.

Any suggestions on what to display? Here's what I think I'll setup for now:

Rail Pressure
MPH
Coolant Temp
Torque (is this even accurate?)
Boost (??) I have a boost gauge already, but why not
Instant MPG (laughable but oh well)

Rob

 

Torque and instant MPG will not be accurate, at all.

You can see in the photo above what I monitor.

There is an alarms sub-menu.

 

Okay, got it all setup and de-alarmed.

And, the rough starting has begun again. I'm seeing rail pressures down around 5000 when it happens, bouncing around 5000-5300-5800 and so on. Then once smooth we're back up at 6800.

Rob

 

Way happens if you try to rev it when running enough?

 

Usually that'll kill it.

Rob

 

Far from knowledgeable about this stuff, but had mine at the Cummins shop the other day and was talking about whether I should replace my injectors ( 173K miles) .. he said the "quick" way to spot an injector problem was to rev teh engine in neutral, and watch the rpms.... if they bounce down rather than go down smoothly, thats a good indication of a bad injector, if its smooth, the injectors are probably OK..

FWITW, he told me that replacing them out of hand due to mileage was really not necessary.

 

By "bounce" down do you mean "hesitate" on their way down, as opposed to just dropping down to idle? Or do you mean bottoming like mine do, before coming up to regular idle?

Rob

 

Well, "bounce" is all he said.. I took that to mean hesitating or going up/down as it dropped...as stated, Im pretty much an idiot about the fueling systems..sorry cant be more help..

 

The problem continues. I've been slammed with other stuff for the last week or so; now it's time to really figure it out and get it fixed.

I tried calling Todd @ T&C a few times. Never an answer. His message says he never checks his voicemail, so to just keep calling. At this rate, it'll never get fixed.

Rob

 

Nevermind! I just got a hold of him. I have a PRV and FCA on the way. Can't beat his prices, holy cow.

Rob