'04.5 Laying down bad

[TFucili]

Fellas,

A good friend of mine back east has an '04. 5 2500 w/48RE. The truck is bone stock except for muffler eliminator. Recently the truck began to just lay down if he jumps on it to merge onto a freeway, or accelerate up a hill with his gooseneck in tow. If he slowly opens the throttle it doesn't seem to do it. When it happens the truck just absolutely bogs down and won't pull worth a darn. No hard starting, no skips or misses, no smoke, and no codes. The in-tank pump was replaced within the last 10,000 miles. He has already replaced the fuel filter with no improvement. I was first thinking that the new lift pump is going bad, but then I was wondering about the relief valve on the rail. Since it happens when he tromps it is it possible that the rail valve is dumping on him when the pressure spike up? Do these go bad on a stock truck?



Thanks,

Tom

P. S. He's originally a Georgia Boy, so don't hold that against him:-laf

 

[Missouri Mule]

Yes I have read that the relief valve (I believe it is known as pop-off valve also) can go bad. There should be a test for it but I don't know much about common rails.

 

[hsmith]

With a good scanner, you can monitor rail pressure while driving. I also am not very knowledgeable about the cr's yet. I use the Snap on Solus. Works great.

 

[JJPage]

If you want to test the rail relief valve, remove the banjo bolt from the the top of the valve, very carefully, bend the fuel line just enough to get it out of the way.



Now, start your truck, if fuel runs out of the top of the valve, it is bad.



My truck sprayed fuel all over the underside of my hood at idle, don't think I would feed it fuel while testing.



The problem could also be his FCA (fuel control actuator), it is a small solenoid attached to the rear of his CP3 injection pump, has a small wiring harness connected to it.



It is held on by three small torx head bolts, If he can find someone with a 3rd gen, who is willing to let him swap FCA's for a test, it is an easy task.



A new FCA is about $100. 00 @ Cummins, $300. 00 @ Dodge. I do not have the part number with me, but if you need it, PM me, and when I get home from work, I'll send it to you.



Jess



It still could be the lift pump!

 

[TFucili]

Thanks for the replies guys! I will pass them along.

 

[TFucili]

As a follow up, the dealer claims fuel pressures check out OK. Can they even read rail pressure with the DRB/Star Scan? They still have not determined what the problem is. This is a dealer who historically has great service. Any other suggestions?

 

[AzCattle]

TFucili, my truck is doing the identical thing as yours. Please let me know what they find if anything. Unfortunately, the dealers in Tucson are not so hot when diagnosing this stuff. Thanks. Mine is a 03/6 speed with about 120K miles on it. Never had it in the shop until now.

 

[Cattletrkr]

Mine did that all last winter and now again here the last few days. When it gets colder I can slap the needle up to 25psi boost and from there it's a struggle. Dealer couldn't find anything odd, truck was reflashed, still no help until it warmed up. Last year I thought the magic # was around 40*, yesterday it was 50*.

There is something goofed up in the programming, that's all that's left. For whatever reason it holds the boost down. It's hard to tell but I don't think it's completely defueling 'cause the EGT's will still keep rising until the boost maxes out... if it ever does. Problem is the same with or without the Juice.

 

[TFucili]

Oh brother...

Sorry to not follow up on this guys. The truck in question is not mine, and is 2,500 miles away, so keep that in mind as I give the results:-laf



It turned out to be a plugged air filter element#@$%!



I had asked if the truck was smoking and he was sure it was not, plus the filter had been replaced very recently. He had lent the truck to a family member who apparently did some serious dirt road busting. They dropped in a new element and all is well I can't imagine that the truck wouldn't smoke like a locomotive

 

[Cattletrkr]

Why can't mine ever be that simple?