Relief valve cap

[1HOT68]

Is it possible for the releif valve to act up intermitantly? My truck sometimes just acts like its lost fuel pressure (I have a gauge and it stays at about 8psi) Usually if you shut it off and coast, then start it back up its fine again until next time?



..... My truck is an 03 HO 6speed With a edge juice with addtude ( it had this problem before I installed the edge) 119000 Miles New injectors new lift pump 9on the filter housing) ... .

 

[1HOT68]

What? No-one knows?

 

[WoodChuck]

What? No-one knows?

Welcome to the TDR.

We're talking Common Rail Fuel injection pressure which runs about 8,000-23,000 PSI or more. The gauge you're refering to sounds like a lift pump guage (ie: before the CP3). You're talking apples to oranges. You might need to start a new thread or do a search from the User CP.

If you suspect the relief valve just pull the banjo bolt out and look for fuel underneath it. If you see any moisture at all it's blown.

 

[CIverson]

Welcome to the TDR.



We're talking Common Rail Fuel injection pressure which runs about 8,000-23,000 PSI or more. The gauge you're refering to sounds like a lift pump guage (ie: before the CP3). You're talking apples to oranges. You might need to start a new thread or do a search from the User CP.



If you suspect the relief valve just pull the banjo bolt out and look for fuel underneath it. If you see any moisture at all it's blown.

I don't beleive that is exactly true. I have had fuel on top of mine when checking, but it doesn't seem to have blown ever. I put in a cap to be sure and there is no difference.



If you take out the banjo, and start up the truck check if there is fuel coming out of the valve, also try and put a load on it to increase the pressure to see if fuel comes out. Then you will know it's bad.

 

[cerberusiam]

Is it possible for the releif valve to act up intermitantly? My truck sometimes just acts like its lost fuel pressure (I have a gauge and it stays at about 8psi) Usually if you shut it off and coast, then start it back up its fine again until next time?



..... My truck is an 03 HO 6speed With a edge juice with addtude ( it had this problem before I installed the edge) 119000 Miles New injectors new lift pump 9on the filter housing) ... .

Generally no, once they pop they stay that way.



Your description sounds more like an intermittent FCA problem. Have you checked for codes?

 

[1HOT68]

NO codes! I wish there were and -or it would just break down and do it all the time! Ive replaced the fca , the fuel pressure sensor , multiple fuel filters, new lift pump (on the filter housing) It has a k&n filtercharger , I droped the tank, and cleaned it out pretty much spotless. It also has brand new bosch stock injectors.



I just went out and removed the bolt on the line to the relief valve ... some fuel trikled out of the line , but that was that. What the Blank could it be!!

 

[cerberusiam]

NO codes! I wish there were and -or it would just break down and do it all the time! Ive replaced the fca , the fuel pressure sensor , multiple fuel filters, new lift pump (on the filter housing) It has a k&n filtercharger , I droped the tank, and cleaned it out pretty much spotless. It also has brand new bosch stock injectors.



I just went out and removed the bolt on the line to the relief valve ... some fuel trikled out of the line , but that was that. What the Blank could it be!!

The injector return is plumbed in the same line as the pressure relief so you could have fuel in there that is not from the valve. The line needs to be disconnected from the valve and then observed. Even then if it is not popping until higher pressures you may not see it.



Might try pluggin the relief valve and see if that makes a diference. Just take the banjo bolt out ad thread the inside of it for an 1/8 pipe plug and install the plug. You can remove it later if needed.



Th other problem could be your CP3 is just not able to keep up with the rail. You should be able to see this on a scanner or rp gauge.

 

[E7mack96]

i capped my stock banjo bolt with holes in it by heating it up with a propane torch and siver soldering the thing full.



It worked great and cost nothing.



Also, on our new DD15 engines, they are using a very similar setup now. The ecm tracks rail pressure and if it spikes 25 times, then you must replace the rail pressure releif valve. They do this to ensure proper peak rail pressures for normal operation.



Also, again, the new DD15 is using an FCA too.

 

[1HOT68]

This probably is just a coincidence but it seems to act up more when its really cold outside , Like today is below zero and it does it way more often.

 

[CIverson]

Why don't you give a better description of the problem. My truck would fall flat on it's face when giving it over a certain amount of throttle. I thought my rail valve was blowing relieving all pressure. It ended up being a dirty air filter. It was sucking all it could until it reached the max flow of the dirty filter.