LB7 Hard start cold

[jimboagogo]

Hello everyone.I have a 2003 K2500 Chevy with a 6.6L LB7 engine.It will only start if plugged in when it goes to 40 F or lower.Have put 2 new Delco batteries in it.Replaced some glow plugs and the buss bars.It runs fine once it is started.The GM dealer say's it won't replace the injectors unless it sets a trouble code.It has 150,000km on it.Could it be injectors or should I check something else.Ps there is battery power to the glow plugs when comanded on.Any ideas or thought's would be appreciated.Jim

[DieselMonk]

it is not the voltage on the glowplugs that tells you that them are good or not. You have to do either a current test with a current clamp then disconnect the wiring from a glow plug one by one and meter them out with a Ohm meter. I am mot sure if the LB7 has an intake heater too or not. I'd also check pos, neg and ground connections.

[jimboagogo]

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I guess I didn't word that correctly Dieselmonk.I accutally removed the glow plugs and cleaned,checked with battery voltage to ensure they work,put anti-sieze on them and re-installed and/or replaced as nessessary.I didn't see an intake heater but I will take another look.My question is if all starting aids are working would it be injectors(too much internal leakage).What can I tell the GM dealer to urge them to put injectors in under the extended warranty?

[DmaxMaverick]

Your engine should have an intake heater. Look at the intake pipe just above/before the intake plenum/manifold in front of the turbo (not the pipe attached to the turbo). There'll be a ~1.25" bung in the pipe, and a large wire/lug attached to the heater. The heater, working or not, won't cause the problems you are experiencing. If you don't find the heater, it may be the emissions region omitting it. 2003 was kind of foggy in this regard.

Rarely does the PCM set codes when the injectors fail. It would be nice if it did, but usually doesn't. If you dealer says otherwise, they either don't want the job, or don't have the experience to get the job. Find another dealer. At the very least, they can test the start up fuel pressure and return rates to verify. With original injectors and the Km's you show, the injectors are the likely suspect. They should be replaced in any case before your warranty runs out.

[jimboagogo]

Thank you for the info it was just what I suspected.What is the warranty in KM?I have access to a snap-on scanner can I check the supply and return rates with it?Or only the Tech-2?Or is the return a flow test?Or can you point me to a thread for diagnosis in this condition?

[DmaxMaverick]

A Snap-On OBD II scanner should be able to read the rail pressure, as well as balance and PWM rates. Balance and PWM will usually indicate if injector(s) are failing. The return rate test is a procedure, not necessarily just a readable figure. If yours is not reaching minimum firing pressure soon enough (delayed start), the fuel pressure is not being developed, or the flow is being dumped somewhere. Once you confirm pump operation and regulator function, the injector(s) will likely be the suspect. The dealer should have done this test, at a minimum.