2005 5.9 3500 48re hard start warm

[AAdams]

cold start can hear pump wait for heat tape and starts , at warmed up normal temp cannot hear pump and willnot fire until oil pressure comes up , when running all is fine. replaced high pressure pump atdodge tec recomendation. did ok for 3000 mi now acting up again.



Not dis respecting your helpful opinion, but, let me go into more detail.

#1 This is my 3rd Dodge 5. 9, 97, 98. 5, 05 so, this means that I have toyed with all 3 generations. It does not mean I am an expert. Let me go throught this process step by step.



When the truck is cold, it starts in 5 to 7 seconds and always has. I hear the electric pump running during the heat cycle. (I understand that this circuit is suppose to run at 1/2 speed and then after starting goes to full speed on the lift pump). The truck under normal operating temperature such as running around town approx 1/2 hour when you park the truck and return probably within 15 minutes does not want to fire immediately until the oil pressure gauge indicates pressure. At this time I can not hear the lift pump the same as I could when it was cold.



When I orginally took the truck to a Dodge dealer and had it put on a scan tool, (the period of time from when I dropped the truck off at the shop until he pulled it in side the tech told me that he bearly got it started). The scan tool showed 0 pressure with ignition on. It showed 11,000 lbs with the soleonoid disconnected. It is suppose to show 11,000 lbs before being disconnected and 25,000 lbs after being disconnected.



The test were performed in a warm shop. I supplied him with a recon pump and he installed it after which with the ignition on it read 5,000 lbs with the soleoind disconnected it read 18,000 lbs. Also, he stated the lift pump was between 5 and 8 lbs, within spec.



Being a transporter I took the truck out on a run from PA to Indianna to Fla and home to PA. In between it started acting up and starting hard when warm. At home after sitting for a day or 2 it starts right up, hence leakin injectors would have bled off over that time element.



I have picked up through bits and pieces that the oil pressure switch may be incorporated in this circuit as well as possibly the fan coolant switch. I have had a couple fan coolant codes but have had no repercusions.



Thank you A Adams. Look forward to hearing your input.

 

[hsmith]

Leaking injectors would be my guess.

 

[sag2]

Not sure I completely understand, but here goes. First of all you can't have any rail pressure with the ignition on. You only have rail pressure when the engine is spinning. It is somewhere near 3000 to get it to fire, and 5-6000 at idle. With the FCA disconnected it should top out about 18-22000. The more important pressure is the set pressure vs. the actual. When cranking and it will not start what is the rail pressure? You need to perform a complete fuel system test to check for excessive pump and/or injector return. Make sure it is done cold and hot, as many times the test will pass cold, but fail hot. Could be as simple as loose connector tube(s).

 

[AAdams]

pleasa pardon my thick headedness! but i cannot get it thru my thick head as to how i am having drain back (loss of prime) in a short period of time but all is well 24 to48 hours later in our se pa weather. are you telling me that my not hearing the pump run when at normal temp makes no difference . please get this thru my thick head.

 

[sag2]

Are you not hearing the lift pump running when hot? It should run for a couple of seconds every time the key is turned on. If you bump the starter and leave the key on the lift pump should run for about 20 seconds. You need to check lift pump pressure and volume as well as high pressure pump pressure as described above.