Crank but no start, suspect injectors.........

[DonFitzwater]

2005 Ram 2500 4x4, auto......267,000 miles. Cranks like a mother but won't start without jimmy juice. Rail pressure cranking is 700-900 psi, waaaay too low. Don't have tools for injector return rate test. Has new fuel rail assembly from Geno's installed with no change in starting performance. Once running, it'll hover around 6700 psi at idle and has rough idle. Cylinder drop test shows even drop on all cylinders. Runs fine at speed.

The strange symptom (besides no fire when cranking which is certainly low rail pressure) is that when the engine is revved up, it'll drop rpm in a stepping down type drop......I'll post a picture of what the Snap-On Solus is showing. Rail pressure graph looks like a set of stairs.......................any idea why the lumpy deceleration? Hopefully it's related to the injectors and it'll be cured with a new set.

 

[DonFitzwater]

Here is a pic of the rail pressure when the engine is revved up slightly and allowed to decelerate to idle.

 

[cerberusiam]

Injectors are toast. A step down de-rev is a sure sign they are not holding and reacting as the ECU demands. You have to do the de-rev test correctly or the results are inconclusive. If you hold rpm at set point for 10-20 seconds then let all the way off the rpms should drop relatively smoothly on the tach, you might see small steps on a graph but that could be sampling rate.

The no start and low rail pressure is too much bypass in the injector cooling circuit.

 

[DonFitzwater]

Ok....kinda figured it was most likely all related to bad injectors. I'll install a new set and post results, thanks!

 

[sag2]

The idle speed not dropping is injector (s) mechanically stuck open. The rail pressure stays up by design when you let off the throttle. The sticking injector keeps fueling the cylinder. Not fixing it ASAP can result in melted piston.

 

[DonFitzwater]

The idle speed not dropping is injector (s) mechanically stuck open. The rail pressure stays up by design when you let off the throttle. The sticking injector keeps fueling the cylinder. Not fixing it ASAP can result in melted piston.

Yep, know this. Will post results after repair.

 

[DonFitzwater]

Update. Installed a set of cheapo injectors (Diesel Logic). Engine fired right up with no Jimmy Juice this time......short test drive, very short. Bang, smoke and now a blown up engine. DON'T BUY CHEAP INJECTORS. DON'T DO IT!!!! Now, the truck is toast. RIP Dodge Cummins.

 

[GrantP]

What happened??

 

[DonFitzwater]

What happened??

Not sure. Engine ran fine for about 1 mile and then made an instantaneous bang/knocking noise and rolling white smoke out the exhaust. Probably not going to dig much farther as funds are low plus it's a tired old truck to boot.

 

[JR]

Is this your rig?

What a bummer!

 

[DonFitzwater]

Is this your rig?

What a bummer!

No, belongs to a friend of a friend. We're going to tear into it in the am so I should know more tomorrow....morbid curiosity got the best of us and we just have to know.

 

[DonFitzwater]

Pulled it down this am.....compression still marginal (at least it didn't drop any and isn't really blown up). One injector has a black tip so I suspect that injector is stuck open causing this God-awful knocking.

 

[cerberusiam]

Yep, one injector hanging and you will swear it ate a piston and a rod is ready to come out the side of the block. Too much fuel firing at the wrong time and it sounds REALLY bad.

 

[DonFitzwater]

Yep, one injector hanging and you will swear it ate a piston and a rod is ready to come out the side of the block. Too much fuel firing at the wrong time and it sounds REALLY bad.

You can say that again! I'm pretty sure it was hanging wide open with the amount of atomized fuel in the exhaust.

 

[DonFitzwater]

FYI- Diesel Logic is going to "warranty" the failed injector. I'll post results.

 

[DonFitzwater]

Diesel logic warrantied the failed injector. Took two weeks. Got the new one installed and drove it for a few miles and now another has failed. DO NOT BUY INJECTORS FROM DIESEL LOGIC IN FLORIDA. They are a joke and do not use quality components. They reman injectors with Chinese garbage parts and it shows.

Buy your injectors from Geno's, TC Diesel or any reputable Bosch shop. Don't cheap #%@ yourself like this guy did.

 

[Missouri Mule]

There is a authorised Bosc shop in Orlando Accurate Diesel Injection. My Mechanic uses them. You ptobably find one in your area.
Ph. no. For one in Orlando 1 800 229 7045.
Supposed to be whats left of a well know diesel fuel system shop that closed down after the epa went on their witch hunt.