By what you described it sounds like a HPO leak cause your not building the needed 500psi and with it being a 03 motor you don't have the STC fitting. I recently just went thru this but I have an 05. I changed the STC fitting cause I had done the normal causes, injectors, dummy plugs and stand pipes, but it turned out to be an injector o-ring on top of #3 and #7 injector as I had gotten a bad batch of O-rings cause they just crumbled as I pulled them out and went ahead and did the upper O-rings on the rest of them on the passenger side. Also this is not a fact but with an 03 it could be your HPOP. Hope some of this helps and someone else will chime in. If it is a HPO leak and not the pump you need to pressurize the system with air to find the leak

 

By the way like your rig and those front fender flares. Who did you get those flares from

 

Thanks for the help! Appreciate it! And they are bushwackers.

 

Short of an air test is there any way to tell if it is in fact a weak hpop?

 

An air test would reveal where the leak would be if in fact you had one, but that's as far as my knowledge goes

I should mention that by hot no start I mean above 190 on oil temp usually anything under and she fires right up. Will eventually fire if I crank on it long enough when hot too but I don't like doing that. Drives like a top when the trucks not been warmed up. Once warm though it doesn't have a lot of balls.

Now by this statement here that it runs fine cold and once it warms up its not very powerful sounds like a friend of mines 03's problem and that was a HPOP going bad. Just by what your explaining to me here it sounds like in fact you have an high pressure oil pump going bad but I am by no means an expert its just what I have seen happen and what I have dealt with and that's VERY limited. I know the 03 to 04.5's have the older design HPOP and they are known to go bad and have the symptoms you have described. The 04.5 thru 07 have a different designed HPOP with the prone to fail STC fitting that now has an update to it so that weak link in the system is addressed but still have to pull the HPOP to do it (which I just did) now that has nothing to do with your truck. I really wish I could be of more help. One thing I did just remember I know on your truck compared to mine is that it is more difficult to perform the air test due to the location of your ICP which is where you install an air fitting to air test the system. Have you done the HPOP in the past? and is this something that has progressively gotten worse? Like I said I wish I could be of more help maybe someone else could chime in. I will keep up with ya on this post and research and do what I can to help as I was just there like you said. My truck on the other hand when hot would not start...WELLLL I could with some help from a friend call ether :nod:

 

I should mention that by hot no start I mean above 190 on oil temp usually anything under and she fires right up. Will eventually fire if I crank on it long enough when hot too but I don't like doing that. Drives like a top when the trucks not been warmed up. Once warm though it doesn't have a lot of balls.

 

Ok guys so who has the best deal on hpops? Early 04 style wouldn't be totally against a higher performance model if the price isn't bad. Thanks.

 

How did ya figure out it was a weak HPOP