s_love9891

My buddy seems to be having some problems out of his 03. Went to get his injectors tested but come to find out, that wasnt the problem. They told him at the dealership that his hard starts are because of this pressure limiting valve due to a internal leakage.

What do you guys think?

... and tell me the difference between it and the fuel control actuator ?

bsg800

did the dealer test the injectors with a scanner? if so all they are doing is shutting it down that is not going to tell you if they are leaking internally they must be removed and tested on a flow bench. if the truck starts after it is plugged in for an hour or the outside temp is higher than 40 deg then you have injector issues

JJPage

If the dealer proved the rail relief/pressure limiting... valve is leaking, and that's fairly simple, then I would replace it.

The relief or limiting valve is installed in the rail manifold that feeds the injectors. It is there to prevent pressure over 26k from cracking injector bodies and tips. It is held shut by an internal spring, once it has operated it gets weak and opens easier with use. This allows fuel to bypass the injectors and flow back to the fuel filter canister. This compromises the pressure needed to start and perform correctly.

The FCA is the electrically controlled solenoid, mounted on the injection pump that controls and stops fuel flow to the injection pump

s_love9891

It seems that its not building pressure in the rail. Well i know they did take them out of the truck to test them. i could of tested them electronically, but needless to say it wasn't the pressure limiting valve. i think that i'm going to test the injectors myself. he's going to buy a new injector and let me interchange one by one while its still cold to see if i can figure it out by process of elimination so to speak. it was a nuisance enough to have to update his programmer because they reflashed his computer. but using a good injector would work wouldnt it? i mean if it was just one injector bad of course.

JJPage

I am generally not mean or sarcastic by nature, but I do not believe you should be working on this particular truck.... Cheers and Sorry in advance!

AH64ID

If its not building pressure in the rail that most likely has nothing to do with the injectors.. Thats a supply or a holding issue... It seems that if the pressure releif valve was diagnosed then I would change that... It fits 10x more than an injector does.

If an injector were leaking that much it would be full of fuel in the oil, and once it got running it would run rough as hell and try to accelerate uncontrollably on that one cylinder.

no_6_oh_no

If I am reading the responses correctly, they changed the RP relief and it didn't fix the problem. If thats true, sound slike the dealer is clueless also.

Yes, the injectors bypassing too much fuel internally will cause low rail pressure on startup. Unless they are cracked its not going to dilute the fuel.

Torque tubes could be loose, o-rings wore also. Testing individual injectors takes some fairly sophisticated equipment so sometimes thats not doable. First thing to do is verify lack of rail pressure cranking, second is an injector return flow test to determine if they are returning too much fuel.

If it indicates an injector problem probably should replace all of them cuz if one is that worn the rest are right there too. You can try swapping one at a time and see if you can hit the bad one or even just cap each injector rail port and see if it will start. If you have more than one that is bad that doesn't work so back to replacing all the injectors with new.

Lots of other things could contribute but check the rail pressure and injector return first.


Good luck.

s_love9891

I know i dont know much about it, but i'm just trying to figure this out so he dosent have to keep buying each part that could be wrong trying to fix it. but thanks for what you guys have told me.

JJPage

That's what these forums are for, I was out of line, I apologize. You are on here asking for help/advice, looking for positive feedback, and my second response was unwarranted. Jess

s_love9891

Well i figured it out, one of the forums on here said to block off each port on the rail one at a time. Sure enough after the 3rd one it started up. Thanks for the advice and help