Hard cold starting

[skorgen]

That hasn't been looked at to my knowledge. Will look into it. Thanks.

Bob

[DmaxMaverick]

How cold is cold? The heater element won't have much of an effect on cold starting unless it gets really cold, like well below freezing. It will help clear up smoke on startup, and smooth out the idle some, but should not cause long cranking starts.

Other possibilities....

Air leak. Are you able to bleed air from the filter housing when it doesn't start?

Excessive fuel tank vacuum. A malfuctioning (or wrong) fuel cap can prevent the relief of vacuum, making it much more difficult for the pump to develop pressure. This condition is exaggerated during winter. The fuel gets hot from running, and cold ambient temps cause much contraction of the fuel and air in the tank as it cools.

Injectors. Injector issues have caused hard starting. Many have reported much quicker starts after injector replacement. High return rates will also cause hard starting, but there should be some indication of a DTC. Keep a close watch on the oil level. If you have injector problems, increased oil level (fuel in the oil) is very possible.

Fuel pump or FRP regulator. If the fuel pump is weak, or the rail pressure regulator is malfunctioning, it will cause hard starts. There should be an associated DTC.

Glow plugs. Verify all plugs are good (easy test with a test light or VOM), and are getting juice. The relay and fuse is under the hood. Is this a CA or federal emmissions truck? It makes a difference as to the diagnostics and operation. The CA trucks are much easier to diagnose, as each plug has its own circuit, and reports current usage of each plug to the PCM.

[mark45678]

time for a trip to the dealer , every duramax truck I have owned starts in 3 seconds with out being pluged in over night. -15*F and you want to have the block heater on after that. sounds like maybe a bad temp sensor that is causeing other problems.

[skorgen]

Thanks for the info. The truck is back at the dealer today and the first thing they did was to replace the conductor connecting the right bank of glow plugs (corroded but not broken) - big job labour wise. I find it hard to believe that's the problem as I have a recently replaced (broken) left side connector and presumably a fully fuctioning bank of plugs on that side.

Jus got a call from the dealer after expressing my scepticism as to the corroded connector. Apparently on further testing there is some indication of an injector problem - wants to keep the truck for another day. Hopefully I'll soon have a functioning truck

Bob

[More Power]

Loosen the fuel tank cap when you park the truck after running it. Dmaxmav might be on the right path. Excessive vacuum in the tank might be a contributor to the hard to start issue. If loosening the tank cap helps, I'd replace it. The cap is supposed to vent at 2 psi positive pressure and at 2" vacuum.

Does any air accumulate in the fuel filter between driving sessions, or after sitting overnight?

Jim

[skorgen]

There is no air in the fuel filter at the time of a no/hard start. I will try the fuel filler on the next cold day.

Got the truck back from the dealer today with the right glow plug conducting strip replaced. I now have to wait for thetemperature to drop. The problem was noticeable in the -5 to -10 C range and it's a balmy 2 or so today. Most likely early next week will be cold again here in Newfoundland.

[skorgen]

Turns out the heater in the fuel filter assembly is not working! They have ordered the part (the full fuel filter assembly) which is over $1000.00 CAD. At first I was told it wasn't covered under the warranty but when I showed them the warranty book (it says the fuel filter assembly is covered for 5 years/160K Km) they agreed to cover it!

Hoping for a good cold start.