Is my rail pressure gague broken???

[Toshiro]

I noticed something else... ... .



After the gauge starts reading high, my egt's at idle will not go below 400 degrees(that's when the rail pressure at idle stays at 10000psi),



normally the idle egt is approx 300 degrees (thats with rail pressure at 6000-7000psi)



So the gauge must be reading somewhat correctly, when the idle pressure is higher the egt's are higher..... Any thoughts?????

Thanks again

Toshiro

 

[MMeier]

Anyone have thier pressure drop to 2500-3000 PSI after a long run on the highway?

 

[Diesel Power]

I noticed something else... ... .



After the gauge starts reading high, my egt's at idle will not go below 400 degrees(that's when the rail pressure at idle stays at 10000psi),



normally the idle egt is approx 300 degrees (thats with rail pressure at 6000-7000psi)



So the gauge must be reading somewhat correctly, when the idle pressure is higher the egt's are higher..... Any thoughts?????

Thanks again

Toshiro

ok here is my thought, tell me exactly how you have your guages hooked up and what are they taped into. the egt has been know to stay around 400 if it is not taped into the correct wires, and i have had 1 other customer say his rp guage was messing up---it turned out to be the way it was wired up, if you have it pluged into any fuse, discconect it. it should be put into the cigarett lighter wire, and the light switch wire, and have its own ground. other than that it's most likely installed wrong.

 

[Toshiro]

ok here is my thought, tell me exactly how you have your guages hooked up and what are they taped into. the egt has been know to stay around 400 if it is not taped into the correct wires, and i have had 1 other customer say his rp guage was messing up---it turned out to be the way it was wired up, if you have it pluged into any fuse, discconect it. it should be put into the cigarett lighter wire, and the light switch wire, and have its own ground. other than that it's most likely installed wrong.

well, the egt's always fall to approx 300 unless the rail pressure gauge is reading high, then the egt's read high (Only observed at idle, driving temps seem normal even when rail pressure is high). . The rail pressure gauge only acts up after I turn on the pressure box... So it seems that DR. P might be causing it...



The gauges are hooked up exactly as you suggest... I used instructions gathered here on the TDR, I used the orange wire behind the light switch (for dimming) and the cig lighter for powered hot... .



everything in my truck is grounded to the battery... I ran a ground wire from the battery into the cab to ground my gauges... you mentioned that the gauge needs its own ground, I am sharing one ground wire from the battery for my RP gauge and the fuel pressure gauge..... could that be it???



I guess my main curiosity is whether the gauge is correct when it is reading high? It just seemed that way since my egt's were a bit higher when the pressure gauge was higher



and thanks again, I appreciate your input, keep it coming if you any ideas...

Toshiro

 

[TCDiesel]

With truck running unplug gage,than with truck running re-connect, should read 5/7. If not correct dis-connect gage truck running,than re-connect truck off check gage, do all of the connecting and re-connecting with the harness on the Back of gage, Report back for the next step depending on readings. Also make sure the dimmer dial on the wire is set at lowest setting.

 

[Toshiro]

With truck running unplug gage,than with truck running re-connect, should read 5/7. If not correct dis-connect gage truck running,than re-connect truck off check gage, do all of the connecting and re-connecting with the harness on the Back of gage, Report back for the next step depending on readings. Also make sure the dimmer dial on the wire is set at lowest setting.

Will do and report back..... one question though...

when you say...



... . "do all of the connecting and re-connecting with the harness on the Back of gage"...



... I assume that you mean to unplug the small rectangle plug from the gauge... . is that correct?

Thanks

Toshiro

 

[TCDiesel]

Will do and report back..... one question though...

when you say...



... . "do all of the connecting and re-connecting with the harness on the Back of gage"...



... I assume that you mean to unplug the small rectangle plug from the gauge... . is that correct?

Thanks

Toshiro

Yes, I think the power from the Dimmer switch may be interfering with the gage.

 

[Toshiro]

Yes, I think the power from the Dimmer switch may be interfering with the gage.

I will run a different power for the light and test...



..... that doesn't explain the higher egt's at idle when the rail pressure is higher at idle... . perhaps it is just a coincidence... .



..... I will attempt to duplicate the issue several times in a row and report back.....



Thanks

Toshiro

 

[Diesel Power]

I will run a different power for the light and test...



..... that doesn't explain the higher egt's at idle when the rail pressure is higher at idle... . perhaps it is just a coincidence... .



..... I will attempt to duplicate the issue several times in a row and report back.....



Thanks

Toshiro

if it is not on the right circuit, it will never go back to its designed set point--0, that would explain the egt problem

 

[Toshiro]

if it is not on the right circuit, it will never go back to its designed set point--0, that would explain the egt problem

please forgive me... I'm feeling a little slow here... .



. . so you're saying that maybe the egt gauge is also reading incorrectly sometimes?... Whatever might be fooling with the pressure gauge might also be messing with the egt gauge as well?...



Thanks again

Toshiro

 

[MMeier]

Anyone have thier pressure drop to 2500-3000 PSI after a long run on the highway?

No one else? Also, finally going to get a chance this week to take both boxes out of truck and see if it does anything for the occasional high readings I get, anyone else done this yet?

 

[qzilla]

Don't know if this will help or not but, it is something to ponder anyhow.



While I was at SEMA I spoke with a couple of gauge manufacturers. It appears that many have went to a newer style stepper motor to control the sweep. From what I understand they are having a lot of difficulty in how the gauge tracks and that it has some sort of memory over time. In other words if you get the gauge to stand in a certain area for a while it always wants to go back?



Now I am not sure why or how but, this was stuff straight from the horses mouth. From what I understand these new Pricol gauges also use a stepper motor? So maybe this is the issue?



Also just for the record, boost fooling does not increase rail pressure. At least if it is doen properly. I can say that for a FACT.

 

[liberty]

Fuel pressure gauge question

I've been reading a few of the threads on fuel pressure, and I have a couple questions on gauges.

Fuel pressure gauges that range from 0-30 psi monitor the pressure that the lift pump is supplying to the injection pump?

and rail pressure gauges monitor the pressures in the common rail and the pressures being delivered to the injectors, is this correct?

I've got an '04 with a Banks 6-gun and speed loader, the dealer has moved the lift pump into the fuel tank because of multiple failures in the stock location. Should I be running fuel and rail pressure gauges?

Thanks for any help you can offer.

Dallas

 

[DLeno]

I've been reading a few of the threads on fuel pressure, and I have a couple questions on gauges.

Fuel pressure gauges that range from 0-30 psi monitor the pressure that the lift pump is supplying to the injection pump?

yes that is correct. this is low-side fuel pressure, or the input to the CP3 (depending on which side of the fuel filter you measure).

and rail pressure gauges monitor the pressures in the common rail and the pressures being delivered to the injectors, is this correct?

yes. note that "pressure in the common rail" and "pressure being delivered to the injectors" is the same thing, for all practical purposes and in the context of measuring it to tell you something meaningful.

I've got an '04 with a Banks 6-gun and speed loader, the dealer has moved the lift pump into the fuel tank because of multiple failures in the stock location. Should I be running fuel and rail pressure gauges?

Thanks for any help you can offer.

Dallas

While the 3rd gen common rail trucks are generally considered to be immune to low side fuel pressure issues (at least compared to the 2nd gen trucks, certainly, where in my opinion it is essential even for a stock truck to have a fuel pressure gauge... ), the 3rd gen trucks can benefit. Or shall I say the owner can benefit.



With your set-up there is probably no real need, but minimally you might consider a low-side fuel pressure gauge at the fuel filter just so that you know what is going on. You won't avoid any catestrophic CP3 failure, for example, by monitoring fuel pressure, but given your experience (lift pump change) I would (if it were me) want to measure it. But I'm a data geek.



and of course, I always recommend running my own rail pressure gauge ( ) but truthfully with your set up its not necessary unless of course you have the interest in knowing what is going on. Running the gauge with a stock truck to learn what rail pressure does under various situations is highly educational. then put the Banks on there and so you can see what it is doing to rail pressure.

 

[JMerola]

MMeier - I am also noticing a 2000-3000 psi drop after a 1. 5 hour highway commute. Starting idle psi is 6-7k, sometimes when I get home is 3-4k at idle in the garage. I'm seeing a lot of variability in the readings at highway speed (65mph). Sometimes it's 15k, sometimes it's 17. 5 or 18k. Not sure what is up with that.



- Jason

 

[DLeno]

The highway readings will vary. thats just the nature of rail pressure. But the idle pressure should be pretty consistent. two thoughts:



1. where is your power connected? it should be inside the cab to a switched source.



2. when you are reading what appears to be low idle pressures, cycle the power on the gauge by removing/re-installing the fuse. You can do this while the truck is running at curb idle with parking brake set. plse report back on the results of this experiment! Also PM me or write me email at:



-- email address removed -- (please remove the underscore from the above address before sending. this is my poor-mans spam filter... )

 

[JasonCzerak]

I've noticed that after I actually hauled stuff (1500#'s I think maybe in the box) on the highway, even for as little as 40 miles one way, the Rail pressure will near 5000psi, maybe a little under... . Unload. go back 40 miles, rail pressure would read 7000. load up again, same thing, 5000psi. once I made the motor do a tiny bit of work.



I ran the truck for a good 6 hours with out shutting her down. about 250 miles driven with all the other stops that day. 2 hours idling I'm sure. it was cold out, 15 degrees in the Sun and a bit windy. (not a good day to move!).



And there were a few times I went WOT loaded to create a little motor heat.



Funny, the first load was the heavy load. . Entering highway I get cut off by the V8 porche SUV. *******. Second load, a bit lighter, This time the turbo V8 porche SUV... Boy what would I have given to be unloaded and no traffic on the second cut off.

 

[Red Ram]

my gauge need help

MMeier - I am also noticing a 2000-3000 psi drop after a 1. 5 hour highway commute. Starting idle psi is 6-7k, sometimes when I get home is 3-4k at idle in the garage. I'm seeing a lot of variability in the readings at highway speed (65mph). Sometimes it's 15k, sometimes it's 17. 5 or 18k. Not sure what is up with that.



- Jason

My gauge doing the same thing. It's not the wiring it's the gauge. brought it in the group buy do it have a warranty on replacement.

 

[DLeno]

tell me where your power wires are hooked up, and the results of the power cycle experiment, and email me. I'd be interested to know more about this behavior --Doug



oh, and you can always work back through the selling dealer to discuss further. ultimately those questions usually fall back on me any way

 

[RobertP]

tell me where your power wires are hooked up, and the results of the power cycle experiment, and email me. I'd be interested to know more about this behavior --Doug



oh, and you can always work back through the selling dealer to discuss further. ultimately those questions usually fall back on me any way

will these results lead to a permanent "fix" for us RP guage guys?