That is the valve response, but not what the ECM commands. The ECM does not command 100% or 0% so it can detect shorts and grounds in the regulator circuit.
Engine wont start - no fuel pressure
- Thread starter mick
- Start date
By start it demands 0% ==> full flow
100% PWM example: driving down the mountain, if you have 98% the pump still flows and you get a 1093
I'm not the EFI-Life guru, which table is the PWM-valve command? I do that out the logical side ...
Just calculated ... you should see 0 V by starting ... around 5.3V - 5.5V idling ( U = R x I , 3.6 Ohm x 1.55 Amp - 1% idle flow)
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Let's get the truck running here guys, rather than point fingers.:hug:
If an injector wire is pinched under the valve covers, it should still start, it just goes in a limp mode and shuts down certain cylinders IIRC. I had it happen once and it sounds like an old farm tractor at idle. Plus we got a P1261 or 1262 code in EFI Live.
I am racking my brain trying to figure out what your issue is because I know we dealt with the same thing at one time (if there is a fuel system issue, my orange truck has been bit by it in one way or another). You have checked all grounds? Tried another FICM?
We had bad injectors and it still would start and run, but our rail pressure maxed at 13k with both pumps unplugged.
All is cool here - just got to move on. Still have to explain
Thats why I dont think its injectors
Good points Ben. We still dont know if its not making fuel pressure or if it is making fuel pressure and not registering it. We are going to start getting serious on it in about one hours time and hopefully put it to bed
We had a similar problem here after installing a rail pressure shim on an LMM. It would crank, but would not build rail pressure according to the Tech 2. Yet would emit white smoke from the tail pipe. My guys worked on it for hours.
I finally went out and in desperation held the throttle to the floor while cranking and she slowly fired up. (Reverted back to my carb days).
Could have been a coincidence. Perhaps an air bubble in the system. You might try loosening the injector lines to bleed the any trapped air.
I've seen this trapped air syndrome on new dry sump engines as well. It prevented us from priming the engine with oil until we loosened the pressure line and let the trapped air escape.
Hope this helps...
Guy
I finally went out and in desperation held the throttle to the floor while cranking and she slowly fired up. (Reverted back to my carb days
).Could have been a coincidence. Perhaps an air bubble in the system. You might try loosening the injector lines to bleed the any trapped air.
I've seen this trapped air syndrome on new dry sump engines as well. It prevented us from priming the engine with oil until we loosened the pressure line and let the trapped air escape.
Hope this helps...
Guy
Checklist:
1. Lift pump on
2. pressure before CP3 lift pump (any fuel return?)
3. FPR is fully open (or stocked closed)
4. FPR the X (7) % DC commanded
5. Rail gets fuel? (unplug one fuel line and see whether fuel SPRAYS out)
6. Rail pressure relief valve open or closed ... bottle test
7. unplug injectors return line and see whether a bit fuel spray comes out
8. measure all injectors nudity
9. measure FPR nudity and resistance of around 3.6 Ohm
10. measure rail pressure sensors signals ... 0.5V 4.5V 5V
11. measure rail pressure nudity
12. unplug CP3 DC connector
...
20. test cam and crank sensor ... clean surface on the sensor?
21. test voltage on cam and crank...
cam:
brown - pink 5V
red - pink 0V
crank:
blue - brown 5V
green - blue 0V
Please feel free and add points ...
1. Lift pump on
2. pressure before CP3 lift pump (any fuel return?)
3. FPR is fully open (or stocked closed)
4. FPR the X (7) % DC commanded
5. Rail gets fuel? (unplug one fuel line and see whether fuel SPRAYS out)
6. Rail pressure relief valve open or closed ... bottle test
7. unplug injectors return line and see whether a bit fuel spray comes out
8. measure all injectors nudity
9. measure FPR nudity and resistance of around 3.6 Ohm
10. measure rail pressure sensors signals ... 0.5V 4.5V 5V
11. measure rail pressure nudity
12. unplug CP3 DC connector
...
20. test cam and crank sensor ... clean surface on the sensor?
21. test voltage on cam and crank...
cam:
brown - pink 5V
red - pink 0V
crank:
blue - brown 5V
green - blue 0V
Please feel free and add points ...
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We had a similar problem here after installing a rail pressure shim on an LMM. It would crank, but would not build rail pressure according to the Tech 2. Yet would emit white smoke from the tail pipe. My guys worked on it for hours.
I finally went out and in desperation held the throttle to the floor while cranking and she slowly fired up. (Reverted back to my carb days
Could have been a coincidence. Perhaps an air bubble in the system. You might try loosening the injector lines to bleed the any trapped air.
I've seen this trapped air syndrome on new dry sump engines as well. It prevented us from priming the engine with oil until we loosened the pressure line and let the trapped air escape.
Hope this helps...
Guy
Bleeding of the CR-system is not necessary, b/c the air gets dissolved in the diesel. But a good point, thought. The system is usually so specified, that by 5 rotation the pressure is reached to fire the shot by 30 - 40 MPA ... now with an empty rail , injector and lines (rail 50ccm, lines and injectors another 50 ccm = total 100 ccm) diveded by 3 ccm rotation per pump ... gives us 33 rotation until the system is completely filled ...
You should never crack the fittings loose on a cr type injection system. the high psi fuel will cut you to the boneWe had a similar problem here after installing a rail pressure shim on an LMM. It would crank, but would not build rail pressure according to the Tech 2. Yet would emit white smoke from the tail pipe. My guys worked on it for hours.
I finally went out and in desperation held the throttle to the floor while cranking and she slowly fired up. (Reverted back to my carb days
Could have been a coincidence. Perhaps an air bubble in the system. You might try loosening the injector lines to bleed the any trapped air.
I've seen this trapped air syndrome on new dry sump engines as well. It prevented us from priming the engine with oil until we loosened the pressure line and let the trapped air escape.
Hope this helps...
Guy
that type of method of removing air out of the fuel system is good for 12v cummins and other low psi systems
2xYou should never crack the fittings loose on a cr type injection system. the high psi fuel will cut you to the bone
but the Bosch CR-System has a build in leak in the injector, so when you stop the engine, automatically the pressure drops down until 100 - 200 psi. Also when you crack a line with still some pressure on it it will might cut you, (distance and flow) but if you go close to an injector with and 0.08mm hole, that cuts right your hand off ... Be careful with high pressure systems ...
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We've got thread full of ideas to continue checking off. But, we look forward to not having to check them all off by finding the fix quick.
Guy we tried the ole-flooded engine carb thing:cool2:
Guy we tried the ole-flooded engine carb thing:cool2:
You should never crack the fittings loose on a cr type injection system. the high psi fuel will cut you to the bone
Thanks for the warning and he will use a long wrench.
As fingers suggested he might just machine a fitting and install a gauge till burst..... At least it's only a gauge.:angel:
The LMM I described before had cranked hundreds of times.
You should never crack the fittings loose on a cr type injection system. the high psi fuel will cut you to the bone
I agree Safety First. :hug:
I appreciate your concern but it is high pressure, low volume. The rail pressure bleeds down so quickly there is virtually no flow, so nothing to "cut you to the bone". Being afraid of what you don't understand is like being afraid of the dark. Once you understand, the fear is gone.
I have done it many many times.
The rail only holds 175-200 psi when not being cranked. Throw a rag over it and loosen the fuel injector nut by approx. 1 turn. Crank the engine for a couple of revs to verify fuel flow at each injector. I usually do this with the glow plugs removed.
We've got thread full of ideas to continue checking off. But, we look forward to not having to check them all off by finding the fix quick.
Guy we tried the ole-flooded engine carb thing:cool2:
Yeah, it was crazy, I was cranking and cranking, giving the starter a rest every 10 seconds or so with my foot to the floor, watching the pressure do nothing and all of a sudden bingo, she built pressure and limped to life.
I just remembered a situation with an air pocket trapped in the FICM that caused a "no start" condition. Might try bleeding the line coming out of the FICM.
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Believe me Guy we have not let this one go for a check mark, he is setting up so we can get started. We both feel like the Cat. injector line bleed is in order. See, he is an old Cat operator/mechanic. Sorta correlates with the old school ways. This might get in the way but hell, he's been right more often then not.
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I have done it many many times.
The rail only holds 175-200 psi when not being cranked. Throw a rag over it and loosen the fuel injector nut by approx. 1 turn. Crank the engine for a couple of revs to verify fuel flow at each injector. Ihey, i wouldnt like anyone to lose a finger doing this, especially when that procedure is not needed for commonrail systems
Why are people still talking about if the rail pressure sensor is giving the ECM a funky reading etc...
THAT AND EVERY OTHER ELECTRONIC CIRCUIT on the engine is IRRELEVANT in this problem!!!!!!!!!!
IF you unplug the FCA and crank it, YOU WILL BUILD RAIL PRESSURE if there are no mechanical/fuel system problems. You dont even need the FICM, ECM, or anything else hooked up to test this. You could have every single wire crossed and shorted out, not gonna make any difference, it will still make rail pressure.
Really, there are not many things that could possibly go wrong here.
1. CP3...good?
2. FCA...good/not full open? (leave it unplugged for now until the engine gets running to make it default to max rail pressure to take the electronics out of the picture)
3. injector lines...tight?
4. rail pressure releif valve....tight and not leaking? Maybe replace with a race valve?
5. injectors...not hung open?
6. CP3 has positive fuel feed pressure to it...good?
7. rail pressure sensor...good? (disconnect and verify with a DMM)
THATS IT. There is nothing else that can cause a no-rail pressure situation, ECM, electronics, wiring, FICM, or otherwise...... I still think people are way overthinking/complicating this. My own guess is you have a small high pressure fuel leak somewhere. Just because its under such high pressure doesnt mean that you are going to see some geyser that shoots to the moon when there is a slight leak (I think people assume this because the system runs under such high pressure). Yes, the CP3 makes insane pressure, but at a very surprisingly small volume. If you have one tiny dribble and go to crank it, that tiny dribble that you might not even see can very easily bleed off enough pressure that the CP3 wont be able to overcome it. Ive had that happen before. Put a motor in, cranked and cranked and cranked. Wouldnt build rail pressure. ZERO visible fuel leaks. I rechecked all the injector lines, one was slightly loose, put another 1/8 turn on it, cranked again while watching the tech 2....sure enough after about 7 seconds, 200psi-350psi-500psi-800psi-1500psi-vroom.
Just my own stupid opinion.
ben
THAT AND EVERY OTHER ELECTRONIC CIRCUIT on the engine is IRRELEVANT in this problem!!!!!!!!!!
IF you unplug the FCA and crank it, YOU WILL BUILD RAIL PRESSURE if there are no mechanical/fuel system problems. You dont even need the FICM, ECM, or anything else hooked up to test this. You could have every single wire crossed and shorted out, not gonna make any difference, it will still make rail pressure.
Really, there are not many things that could possibly go wrong here.
1. CP3...good?
2. FCA...good/not full open? (leave it unplugged for now until the engine gets running to make it default to max rail pressure to take the electronics out of the picture)
3. injector lines...tight?
4. rail pressure releif valve....tight and not leaking? Maybe replace with a race valve?
5. injectors...not hung open?
6. CP3 has positive fuel feed pressure to it...good?
7. rail pressure sensor...good? (disconnect and verify with a DMM)
THATS IT. There is nothing else that can cause a no-rail pressure situation, ECM, electronics, wiring, FICM, or otherwise...... I still think people are way overthinking/complicating this. My own guess is you have a small high pressure fuel leak somewhere. Just because its under such high pressure doesnt mean that you are going to see some geyser that shoots to the moon when there is a slight leak (I think people assume this because the system runs under such high pressure). Yes, the CP3 makes insane pressure, but at a very surprisingly small volume. If you have one tiny dribble and go to crank it, that tiny dribble that you might not even see can very easily bleed off enough pressure that the CP3 wont be able to overcome it. Ive had that happen before. Put a motor in, cranked and cranked and cranked. Wouldnt build rail pressure. ZERO visible fuel leaks. I rechecked all the injector lines, one was slightly loose, put another 1/8 turn on it, cranked again while watching the tech 2....sure enough after about 7 seconds, 200psi-350psi-500psi-800psi-1500psi-vroom.
Just my own stupid opinion.
ben
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Why are people still talking about if the rail pressure sensor is giving the ECM a funky reading etc...
THAT AND EVERY OTHER ELECTRONIC CIRCUIT on the engine is IRRELEVANT in this problem!!!!!!!!!!
IF you unplug the FCA and crank it, YOU WILL BUILD RAIL PRESSURE if there are no mechanical/fuel system problems. You dont even need the FICM, ECM, or anything else hooked up to test this. You could have every single wire crossed and shorted out, not gonna make any difference, it will still make rail pressure.
Really, there are not many things that could possibly go wrong here.
1. CP3...good? Yes, we have two and have swapped back and forth.
2. FCA...good/not full open? (leave it unplugged for now until the engine gets running to make it default to max rail pressure to take the electronics out of the picture) Yes, disconnected
3. injector lines...tight? Yes, no leaks
4. rail pressure releif valve....tight and not leaking? Maybe replace with a race valve? Confirmed no leaks, removed return off the rail and cycled.
5. injectors...not hung open? Nothing coming from glow plug holes since new injectors installed.
6. CP3 has positive fuel feed pressure to it...good? 10+ psi
7. rail pressure sensor...good? (disconnect and verify with a DMM) Attached post but also sensor removed and replaced from 05 lly donor truck.
THATS IT. There is nothing else that can cause a no-rail pressure situation, ECM, electronics, wiring, FICM, or otherwise...... I still think people are way overthinking/complicating this.
Just my own stupid opinion.
ben
We are still working on a manual gauge to confirm rail pressure.
Why are people still talking about if the rail pressure sensor is giving the ECM a funky reading etc...
THAT AND EVERY OTHER ELECTRONIC CIRCUIT on the engine is IRRELEVANT in this problem!!!!!!!!!!
IF you unplug the FCA and crank it, YOU WILL BUILD RAIL PRESSURE if there are no mechanical/fuel system problems. You dont even need the FICM, ECM, or anything else hooked up to test this. You could have every single wire crossed and shorted out, not gonna make any difference, it will still make rail pressure.
Really, there are not many things that could possibly go wrong here.
1. CP3...good?
2. FCA...good/not full open? (leave it unplugged for now until the engine gets running to make it default to max rail pressure to take the electronics out of the picture)
3. injector lines...tight?
4. rail pressure releif valve....tight and not leaking? Maybe replace with a race valve?
5. injectors...not hung open?
6. CP3 has positive fuel feed pressure to it...good?
7. rail pressure sensor...good? (disconnect and verify with a DMM)
THATS IT. There is nothing else that can cause a no-rail pressure situation, ECM, electronics, wiring, FICM, or otherwise...... I still think people are way overthinking/complicating this. My own guess is you have a small high pressure fuel leak somewhere. Just because its under such high pressure doesnt mean that you are going to see some geyser that shoots to the moon when there is a slight leak (I think people assume this because the system runs under such high pressure). Yes, the CP3 makes insane pressure, but at a very surprisingly small volume. If you have one tiny dribble and go to crank it, that tiny dribble that you might not even see can very easily bleed off enough pressure that the CP3 wont be able to overcome it. Ive had that happen before. Put a motor in, cranked and cranked and cranked. Wouldnt build rail pressure. ZERO visible fuel leaks. I rechecked all the injector lines, one was slightly loose, put another 1/8 turn on it, cranked again while watching the tech 2....sure enough after about 7 seconds, 200psi-350psi-500psi-800psi-1500psi-vroom.
Just my own stupid opinion.
ben
I see you added more since I posted. He is now looking for a fuel leak. ? Not so far but????? No gauge at this time