2012 Isx 2350 475 with codes 4726 and 0559

[Rawze]

will it pass a fuel rail leak test?

http://rawze.com/forums/showthread.php?t...2#pid69262

[Lonestar10]

If no issues in pumping system find a cap off kit for injectors and cap off rail and test pressures.

Also fuel actuators can go bad if that hasn't been rules out

[ahrenbenjudah]

(02-16-2022 )Rawze Wrote:  will it pass a fuel rail leak test?

http://rawze.com/forums/showthread.php?t...2#pid69262

It only cranks so I can’t do a rail leakdown test unfortunately. If I key on, the rail is fluctuating between -50 and -10 psi. That’s with a new pressure sensor installed and a new relief valve installed.

[Rawze]

(02-17-2022 )ahrenbenjudah Wrote:  It only cranks so I can’t do a rail leakdown test unfortunately. If I key on, the rail is fluctuating between -50 and -10 psi. That’s with a new pressure sensor installed and a new relief valve installed.

with the key on and the electric fuel pump running, does it have plenty of fuel flow and pressure at the compu-check test port when its pressed in?

[ahrenbenjudah]

I’m expecting a set of compucheck gauges in the mail tomorrow to run that test. I haven’t tried it with it just my compucheck to hose fitting in a bucket yet.

[Rawze]

(02-17-2022 )ahrenbenjudah Wrote:  I’m expecting a set of compucheck gauges in the mail tomorrow to run that test. I haven’t tried it with it just my compucheck to hose fitting in a bucket yet.

I always just press it in with a phillips screwdriver for about 2-3 seconds and see if fuel sprays out of it nice and strong without falling off.

[ahrenbenjudah]

Ok, I'm back.

Took forever to get the gauges in hand. And then its been below freezing for near on a week here.

So following the Cummins diag tree, I checked the fuel pressure of the lift pump at the filter manifold. Install a compucheck and cycle the key, psi should be above 10psi. Mine reaches about 16.

Then checked the fuel pressure of the high pressure pump at the filter manifold. Crank for at least 10 seconds at 150rpms or better with the lift pump not plugged in. Pressure should be above 10psi, mine reached about 30.

Double checked the pressure relief valve (I installed a new one at the very beginning of this debacle). Cummins test is replace the banjo bolt with a banjo test fitting and install a hose to the end of the test fitting. Put it in a bucket, do 4 cycles of 15 second cranking. No more than 10 drops in total is the allowance. Mine didn't drip at all.

I'm about to go back out and do the High-Pressure Fuel Pump Return Flow Test. Which will tell me if the pump head is bad or the fuel pump adapter/inlet metering valve is bad.

[ahrenbenjudah]

Update. Okay. So I did the high pressure fuel pump return flow test. Crank until you get a steady stream of fuel, once you have that steady stream, put your hose in to a graduated cylinder for 15 seconds. Do that twice. If the fuel you collected is over 350ml then the head is bad. If its under 150ml, the fuel pump actuator is bad. I never really got a steady stream, but collected about 90-100ml over 30 seconds. So, down to KW to get an actuator. $550 later, slap it on, and still the same issue.

No fuel pressure in the rail at key on, truck will crank and crank.

So I got a wild hair and while I was cranking it, juiced it with some starting fluid. She started up after a second and kept running. Insite hooked up to it while running and the pressure stayed at what was commanded. I let it run for a bit, then I shut it down while having the data logger open. As soon as the key was off, I lost ALL pressure in the rail. Immediately.

Cranked her back up and she started again no issues. I figured I would run an injector performance test to see if any of them were underperforming. I was able to start the test, but before it could finish the first injector, the test stopped because the fuel rail decay was too severe to continue the test.

Truck wanted to run a regen so I let it, it completed that with no issues. After that was finished, I checked for any codes and I have a 4726-Engine Fuel Leakage-Data Valid But Above Normal Operating Range-Moderately Severe Level.

So, Insite says to do an injector test, which I can't do, but I can do an isolation test which is the alternative. Then it says to test the pressure relief valve. So hopefully I can get to that first thing in the morning. It has since starting dumping buckets here and I'm tired of being wet.

[Rawze]

(03-02-2022 )ahrenbenjudah Wrote:  ...
So, Insite says to do an injector test, which I can't do, ...

sounds to me like an injector or 2 leaking and bleeding fuel off too fast?. There are other ways to leak-check injectors for this, in a no-start conditions...

maybe this helps ...
http://rawze.com/forums/showthread.php?t...0#pid48500
and...
http://rawze.com/forums/showthread.php?t...56#pid2556