Dunno know if the truck has any programmers or boxes but if this truck is the 555 h.o. then a good chance it could be a valve these year models are none for it if the truck has been pushed hard. Trust me I know just spent about $10,000 after one of my valves dropped and one got jammed back in the head,but I also added alot more go fast goodies when I went back with my new head.

I know it sounds a little deep but if a vaqlve gets jammed back into the head lack mine did it'll sound just like a dead injector. Just trying to help elimnate some possibilities.

 

no way its a valve idles very smoth now - I say no way - just never expericed a valve prob on such a smoth running engine

Thaks

My guess is software problem

Common - need some more educated guesses

Yall fraid to be wrong??? Go for it .

 

For one, that is a BIG drop off in pressure. You should only experience 2-3 PSI drop at most, 4 PSI under boost with a FASS pump. I will also add though, that even with such a big drop in fuel pressure, if you are seeing 10 LBS of pressure AT the CP3, that is MORE than enough. Is the reading being taken before or after teh fuel filter?

Second, you still have not answered all my questions. Are you really reading my posts? Man, I am tryinglike heck to help you out, but you are making it real difficult. I also asked you about the Cp3 pressure. Do you have a gauge on that as well? If so, what are teh CP3 readigns/pressure?

PLEASE read my other posts carefully, as well as this one.

 

Maybe you had a faulty engine, or something else, but you do realize that there are thousands of 03 owners on this site that run the dickens out of their trucks (inlcuding me and my 150K miles) and not dropping valves. SOunds like you had an EGT problem, too hot, burnt a valve. So, maybe your tune/program was off? Weak pump, no fuel? Could have been a million things, but it is NOT because it was an '03 555 motor, I can tell you that. Also, $10,000 for a reworked head WOW Not sure if you dropped a valve, which would have damaged the piston and more than likely the cylinder wall, or if you just burnt a valve and it got sucked back up into teh head, and that too, is not a 555 problem. If you DROPPED a valve, a broken valve spring, or the valve stem broke is what caused it, and once again, not becasue it was a 555 motor.

 

Sorry,

I do not have CP3 preasure.

My low preasure readings are just after filter

 

I know its not a valve prob. & my trucks an 04. I think it is comp. problem sensor prob. Dealer #2 has had it all day siad they would call back this morning - I suspect they are stumped so far

But I will let ya know. I think Dealer #1 did something to ECM programing, but that is an uninformed guess

Anyone know the high presure pump fuel input preasure specifications? max - min and volume?

 

my truck is also stock . except for the very loud FASS pump I installed.

 

Have said this already, but will say it again. @ 10 PSI is stock, give or take. When mine was going out, would read 5-7PSI and drop to 1-2PSI under boost, and tehn finally hit 0 under boost. I replaced the stock LP with teh Walbro 392 and is putting out @ 130 PSI, and I have it regulated down to 20PSI to keep from blowing the stock fuel filter lid off, as it is good for about 35PSI. If you replace the stock plastic lid with the aftermarket aluminum lid, you can pump even more pressure to the CP3. I do not know what teh absolute limit on what the pressure teh CP3 can receive,but I can PROMISE you it is ALOT more than then the 20 PSI mine is seeing. OK? I would have to assume their is really no limit on what it can see (nothing to damage at these pressure's) And I will say this again, there are THOUSANDS of members on this VERY site, that are running the FASS and Walbro, and thier CP3's are just fine. So, you do NOT need to worry about putting too much pressure to the CP3.

I would next look for pressure AFTER CP3, and see what you are getting.

 

yea CP3 preasure is a need to know #

thanks

 

A big help might be to check for codes. Turn your key in the ignition from off to on 3 times without starting it. Once it is in the on position of the third cycle leave it there. In the odo window you will see some codes come up if there are any present. They will say something like PO628. It will cycle through them rather quickly so be ready to write them down fast. If there are no codes then the odo will go to dashes and then say done and then go back to showing the odo reading in miles. Report back on what codes you have or let us know if there are none.

Next thing, when the CP3 (high pressure pump) was replaced do you know if the FCA was replaced as well? You could ask the place where you bought it from I would suspect. Most come with new ones but once in a while a pump that cheap doesn't come with one so just trying to clear that up. The FCA is what gets the reading or commanded fuel rail pressure from the ECU and then that tells the CP3 what to do. If the FCA is faulty it can cause problems like you state.

Also, since your truck is an 04 but has an in tank pump then the factory fuel filter housing mounted pump was already warranteed by a dealer and was upfitted to the in tank. 03-04.5 had filter housing mounted lift pumps. 05-07 have in tank from factory. Since this is the case, it would be prudent to know which FASS you have. Is it the full with filters and bypassed the factory fuel filter housing or is it just the pump and is still using the factory filter? I have just the pump kind and I run about 20 PSI to the factory filter housing but I have the billett lid. The fitting for the back of the filter housing where the fuel enters could be leaking air and causing funny pressures. If that is bypassed with the full FASS then obviously that is not an area we would focus on.

 

Very good point, and one I did not mention cuz I got so wrapped up in this fuel pressure debate I did forget about trouble codes, but also, he did not mention any check engine light on, so.....

That is why itis good for other members to chime in, as other members (myself) forget teh obvious

 

It's a confusing thread to say the least so getting back to the basics is usually helpful.

 

That's a big 10-4!

 

I just remembered one other strange thing that used to happen on 03-04 trucks not all but some. There is a harness that runs to the fan on these trucks down by the front of the engine on the passenger side that gets chewed up. Once that happens the ECU gets a little quirky. The fix is to simply repair the wire and route it so it isn't bound and grounding on anything and making proper contact. A visual of the wire harness is usually enough to see if that's causing the problem. You might try searching for some of those old threads. But, one thing at a time.

 

Found a thread with information about CP3's

https://www.dieseltruckresource.com/...p/t-78702.html