Hard start when warm

[PHenry]

Any help on diagnosing would be very much appreciated. I have an 03 SO with 220k. Last week I suddenly began having difficulty starting the truck, but only when it is warm. I have checked repeatedly, and it has thrown no codes. Is this most likely an injector issue? I have a FASS pump, which is only 45k old (about 2 years). Any ideas where to look? Thanks.

 

[cerberusiam]

Retorque the cross over tubes first to see if that helps. If it doesn't help or doesn't help for long probably time to think about injectors.

 

[BIGNASTY]

cerberusiam is that because of pressure leak down in the system? On mine you hit the key and its started. But Sons takes a little more cranking not much but its noticeable.

 

[JJPage]

Retorque the cross over tubes first to see if that helps. If it doesn't help or doesn't help for long probably time to think about injectors.

From personal experience, this is what I would do also. When the fuel is warm it's thinner, leaks a greater volume through loose cross tubes. It can also go the other way, when engine is cold the tolerance between the cross tube and injector is greater, making it hard to start when cold.



Yes BIG, it's from loss of rail pressure while cranking, rail pressure has to reach a minimum(around 3500psi) before the ecm will command the injector solenoids to fire.

 

[cerberusiam]

cerberusiam is that because of pressure leak down in the system? On mine you hit the key and its started. But Sons takes a little more cranking not much but its noticeable.

Worn injectors, worn CP-3, FCA not just right, cross over tubes a little loose, or just the way the truck starts. As long as they start on a slow 3 count its pretty normal.



You would think loose tubes would casue a cold start problem but its almost always opposite. Once they reach operating temp they either long crank or won't start at all. The temp change forces a change in the tubes that are not loose causing more of a leak warm. They need to be TQ'ed right or they just won't work.



TQ them and it starts better your lucky. If it goes back to hard starts in a relatively short time its almost always injectors. At 220k the OP is getting to the point where they are suspect unless they have had 2-3 um filtering their whole life.

 

[BIGNASTY]

Thanks I think that his would be injectors just because of the black box that he has had on it for ever and his injectors nozzles were replaced with different ones more HP. I didn't want to say I told you so but ive always believed that cummins might know just a little something when they put these things together. I was young once but cant remember it to clearly but I do remember that I liked to go faster than the other cars so I dont blame him.



BIG

 

[PHenry]

Thanks for the help.

The idiotic follow up question is: Where are the cross over tubes?



Thanks again.

 

[cerberusiam]

Inside the head. Follow the lines from the rail to where they connect to the head. The cross over tubes carry the fuel from ther eto the injector. Tubes are behind the the larger nut seated to the head.

 

[JJPage]

Thanks I think that his would be injectors just because of the black box that he has had on it for ever and his injectors nozzles were replaced with different ones more HP. I didn't want to say I told you so but ive always believed that cummins might know just a little something when they put these things together. I was young once but cant remember it to clearly but I do remember that I liked to go faster than the other cars so I dont blame him.



BIG

When he had his injector nozzles replaced, they had to have removed and re-torqued his cross tubes. I would re-check for proper torque (39 ft lbs).



I had done the same thing, and approximately 7k miles later I was having the same symptoms of long crank times, to just up and dying.



I had to limp into DSM in Kellogg one morning and they found all my cross tubes loose. This was after we went for a ride with their Starscan tool connected to my OBDII port which showed no problems, but they did an injector return flow test and I can't remember exactly, but I was returning something like 240 ml in 30 seconds. After the re-torque it was down to under 100 ml.



I have re-checked them several times since and they have always been good, and no more problems either. I believe a mild loctite may be a good thing, because I know some folks have had them come loose with a completely un-molested truck.



PHenry, here is a link from sag2, injector install procedure w/photos, which shows the cross connect tubes. https://www.turbodieselregister.com...148621-injector-install-procedure-photos.html

 

[PHenry]

Thanks for all the help!