Hard starting 5.9
 

I am hoping someone can give me a little insight on a hard start problem. I have a 2000 5.9 with an Edge module as the only upgrade. I have been experiencing a hard start when the truck is warm for a little while. This does not occur during cool weather and is not quite as bad after the truck has set overnight. I have read the posts pointing towards the VP being bad and have tried many of the troubleshooting techniques without coming to a definite conclusion. What I have found is if the truck doesn't start, I can have someone else engage the ignition while I open the Schroeder (?) valve on the injection pump and it starts right up. I have also had some success by removing and re-inserting the fuel filter. I have checked the pressure off of the lift pump and at the injector pump which is around 17 psi. It almost sounds like I am getting a vapor lock of some type in the fuel system. I do not see any fuel drips on any of the lines and have check the banjo fittings and injector lines to make sure they are tight.
Any suggestions?

What is your configuration (add info to your signature ...)?
Do you have fuel pressure gauge to monitor fuel pressure as you try to start the engine?

(Vapor lock - diesel fuel is no where near as volatile as gasoline, so while gas lines might vapor lock - with diesel - far less so!) Other people have posted that it can be very hard to start the engine if there is very high pressure (the lift pump is putting excessively high fuel pressure to the IP) ...and opening the Shrader valve allows the pressure to bleed off, making it easier to start. [I have heard that it is best if initial LP fuel pressure to the IP does not exceed 20 psi, or starting can be difficult.]

What type Lift Pump do you have? Do you have an active/on-line fuel pressure gauge? If so ...what does the gauge show fuel pressure is before you turn the key ...and as you turn the key. If you bump the ignition key to start briefly - does the LP run for 10 - 20 seconds ....and what is the pressure seen? Answers to these will help troubleshoot!

I do not have any in-cab pressure monitoring. I checked the pressure on the Shrader valves on the filter housing and the IP with the lift pump operating and both the engine not running and running. It was really consistent around 17 psi.

I have an aftermarket OEM replacement lift pump. Not a FASS or other upgraded lift pump. The lift pump ususally does not run at all until after I have tried to start the engine and turned the key back off. Then it will run for 30 seconds or so before sutting off.

There is a banjo bolt on the back of the head that loosens up. I would start there and tighten it (#9 on 24v Fuel System PDF). If that doesn't fix your problem your overflow valve could be going out (Overflow Pic). If that doesn't fix it then your IP is going out, which is what it sounds like to me.

Thanks! I will check those two out. I had checked the banjo on the back of the head but once more wont hurt. Just hoping not to have to do a IP. But it is what it is.

Thanks again!

Let us know how it turns out....:tu:

Just my two cents if the cross over tube O rings are bad they can lead to a hardstart problem. that requires pulliing the injection lines.

I guess I am not sure what you are referring to as the cross over tube.

Cross over tubes deliver fuel from the side of the head into the center to the injectors. Your fuel lines that enter the side of the head actually seat on the cross over tube... I have a limit of reusing these tubes 2-3 times with new o rings. Generally only 2 times but 3 is the limit... When I say reuse I mean when you do a injector swap or change you have to pull the tubes, the tube pressure seat on both ends and re using the ends to many times causes a flare and then they do not seat right and then your stuck in a bad situation... Hope this helps, it made since in my mind...haha

Hello new to the forum, not trying to steal your thread here, but I have very similar problems with my cummins, when it sits over night or even several hours, I takes about 10 seconds to start, fuel is bleeding down. I have a leak under my truck tonight I tightned the banjo bolt on the back of the head they were all loose, and very difficult to tighten. I took the truck for a drive after and let it idle in the drive way, there was a fuel leak and it's not coming from lines I just tightened, seems to be coming from the back of the head. You guys were talking about the crossover tube o rings, does anyone have a diagram? I can't see the back of the head very well, but i imagine you would have to remove the valve cover to get a better look.
Thanks Adriaan