2004 Ford F550, not start when engine is hot,

Cold start is OK. When engine turn off, can’t start until engine is cold down. Any comments are appreciated.

Does it crank but not start? Not even crank? Make any noise, clicking, any sound when you tur the key? Nothing? What engine? The more pertinent information you give, the better answers you will get.

PvtPublic is correct we need more information.

I can only assume your vehicle is equipped with a 6.0L diesel and not the 6.8L V10 gas engine. Hard/no start hot concerns are fairly typically for older or seasoned 6.0L diesels. Most cases of this type are usually due to a leak in the high pressure oil system which activates the diesel fuel injectors. The injectors in the 6.0 are electrically triggered but hydraulically actuated. So if there is a leak in the hp oiling system, the injectors will not deliver fuel. Minimum HP oil pressure MUST be 500 psi to get the injector to at leak spray. Anything under 500 psi, the injectors will not spray and therefore the engine will not run.

Oil leaks can be typically found at the injector D rings (Where the oil is fed into the injectors), oil manifold stand pipe seals or manifold block off plugs. (There are engine fuel system differences between the early 2003-2004 and 2004.25 and latter engines, so specific leak locations can vary a little. In most cases the seal rings have deformed over time and seal the oil enough to make the minimum required pressure when the engine is cold and the oil is thick… When hot and the oil thins, the seals cannot adequately contain the pressure and you cannot make the minimum pressure requirements.

Someone is going to have to see what the ICP (Injection Control Pressure) is doing when the concern is present. Close attention will also need paid to the IPR (Injection pressure regulator) command state as well a some other module parameters (FICM sync, PCM sync, RPM during crank, injector/FICM main/logic/vpwr voltages. These areas of information will provide a clear view of what is causing the lack of engine start.

To be honest, you are going to want to find a garage that is competent is this engine… You really don’t want someone blindly poking around in this thing. (Little workmanship mistakes can often turn out very badly) This is NOT to say you have to take it to a dealer… Dealer labor rates for 6.0 work are ridiculous.


“I can only assume your vehicle is equipped with a 6.0L diesel and not the 6.8L V10 gas engine.”

And I can only assume OP’s vehicle is equipped with a 6.8L V10 gas engine and not a 6.0L diesel engine

Why do I say that . . . because I’m a fleet mechanic, and we have lots of F550 trucks of various model years. And all of them have the 6.8 liter gasoline V10 engine

My point is this . . . I believe it’s pointless at this point to provide any specific advice, because have almost no useful information

I could counter you and provide advice specific for the gasoline engine. But as I just said, I believe it’s pointless right now :neutral:

Agreed… It is pointless… We know nothing about this case with additional input

I was going off our normal shop statistics.

What’s it do when you try to start it?

Thank you very much for all your comments!
It is 6.0 L Diesel engine. Cold start is normal. When shot off the engine, such as at gas station to fill the fuel, will not start until the engine is cool down after server hours. the crack shift is turning, but not start when it is hot.
The engine runs rough, since the #3, 5, 7 injectors and fuel pressure regulator (3C3Z-9T517) should be replaced, and fuel pressure is low per dealership’s suggestion.
The truck was repaired in the dealer’s shop in 2012, they replaced #2 injector, replaced regulator (9C968) and High Pressure Oil Pump.

Injectors are operated by solenoids. Solenoids have windings. Any device with windings can become heat sensitive when it ages. The lifespan of a given set of injectors is pretty consistent, and my feeling is that the other injectors should have also been replaced in 2012 when the #2 was changed. Not everyone agrees, but that’s my feeling.

And you already know the #3, 5, and 7 injectors need changing.

What is the fuel pressure? Do you have the dealer’s reading?

In short, I suspect you have fuel metering problems when the engine is hot. Compounded by low fuel pressure.

This case screams high pressure oil leaks…We deal with this stuff day in and day out. Electric faults in the injectors usually give you a dead hole or misfire. Oil leaks result in hard starts/no starts hot and worsen until you have a no start all of the time. We can argue this till the cows come home… Someone needs to pull codes and then watch ICP and the other parameters when the concern is present to get a clear picture of what is happening. Again you do NOT want to be roaming thru this engine blind… Collect the data, get a picture of what is happening, then go into the engine.

Here is a really well done website related to the Ford Diesel engines… Within this site are the coffee table books which provide a great break down into how these engines are put together and how the HUEI injection system works… Your truck will either have the 2003-2004 engine or the 2004.25… (There was a mid year change to engine for the 2004 model year) Those are the books you need to look at. The 2005-2007 engine are a bit different yet.


There is an easy way to tell which engine you have by the location of the ICP sensor… Common oil leak location a different depending on what engine you have.

The site also has photo galleries of failed components. some of which include HP oil system failures. Really well done site, highly recommend you check it out for anyone interested in Ford diesels.