Erratic Rail Pressure

S

styx53

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Jan 24, 2008
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I have a Dipricol rail pressure gauge and lately I have been seeing fluctuations of about 2000-3000 psi. For example, at idle my gauge bounces back and forth between 3000 and 5000 psi. It bounces up and down probably about 2 times a second. I have watched my rpm gauge and my rpm's stay constant according to the gauge but can hear my engine surging slightly. My rail pressure also fluctuates 2000-3000 psi when I am at a constant speed, not just at idle. Does anyone know what this could be?
 
well it could be a FCA going bad, fuel pump acting erratically, injectors having issues or just a bad gauge ????

I asked about duals because DiPricol RP gauges have a problem with duals and they've come out with a resistor for the gauge that fixed it.

Does the truck have any codes ?
 
No, it has not thrown any codes and my fuel pressure stays at a solid 27psi.
 
i forgot you mentioned that. I think your best bet is to get it on a Starscan to see what's going on. Then you'll know exactly what you need to do. If it's not running rough, idling bad, not having starting issues... it's likely not the injectors.
It could be a RP sensor, the TPS, FCA.... no real way of knowing without codes and/or a scan or just replacing things.
 
For the guys that are looking for Pressure Sensor,LV and FCA,I have at lease 50 of each LV and Pressure sensor and about 15 FCAs.. I just don't want to Ebay them.. they would be awesome for spare or replacement.Just contact us.
 
TCDiesel said:
For the guys that are looking for Pressure Sensor,LV and FCA,I have at lease 50 of each LV and Pressure sensor and about 15 FCAs.. I just don't want to Ebay them.. they would be awesome for spare or replacement.Just contact us.
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Good to know Todd.... those sensors aren't cheap through the regular sources
 
Is it cold where your at...

When My grid heaters cycle the RP jumps from 6-4-6k rpm stays normal
 
ive got a couple old dipricol gauges that work fine never had issues with them. ive been around those junk ass isspro gauges and I wont ever buy them. I recently bought an autometer fuel pressure gauge brand new and im not impressed by it either. I believe the whole voltage thing with the rail pressure gauge trashes them and NOT just dipricol either the quadzilla rail gauges had tons of issues also so dipricol isnt the only one.
 
nomercy said:
ive got a couple old dipricol gauges that work fine never had issues with them. ive been around those junk ass isspro gauges and I wont ever buy them. I recently bought an autometer fuel pressure gauge brand new and im not impressed by it either. I believe the whole voltage thing with the rail pressure gauge trashes them and NOT just dipricol either the quadzilla rail gauges had tons of issues also so dipricol isnt the only one.
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nomercy,
What problems have you had with ISSPRO gauges? Have you contacted the factory on your problems? I'm not trying to be argumentative, I just want to make sure our customers are taken care of. You may not be aware of our current products like Performax and EV², which are all new and have been tested beyond anything else in the automotive aftermarket.

To the original poster, I have heard of some trucks with oscillation in their rail pressure, but not as severe as you are seeing. Just to eliminate it as a possibility, have you tried running the truck with the gauge and harness out of the system to make sure it is not part of the issue?

Regards,
Michael Pliska
 
styx53 said:
I have a Dipricol rail pressure gauge and lately I have been seeing fluctuations of about 2000-3000 psi. For example, at idle my gauge bounces back and forth between 3000 and 5000 psi. It bounces up and down probably about 2 times a second. I have watched my rpm gauge and my rpm's stay constant according to the gauge but can hear my engine surging slightly. My rail pressure also fluctuates 2000-3000 psi when I am at a constant speed, not just at idle. Does anyone know what this could be?
Click to expand...

My truck does the exact same thing. Maybe it's an 03 thing.
 
styx53 said:
I have a Dipricol rail pressure gauge and lately I have been seeing fluctuations of about 2000-3000 psi. For example, at idle my gauge bounces back and forth between 3000 and 5000 psi. It bounces up and down probably about 2 times a second. I have watched my rpm gauge and my rpm's stay constant according to the gauge but can hear my engine surging slightly. My rail pressure also fluctuates 2000-3000 psi when I am at a constant speed, not just at idle. Does anyone know what this could be?
Click to expand...

I would say 80% of the Dipricol gauges I have sold have had issues like this, some go as far as the truck running real rough. Take the harness off the truck, then see if you still have surging. If it continues pull the box off of it, and put a scanner on the truck and read rp via the ecm. You can read what the ecm is asking for, and what it is actually getting with a good scanner.

Does your gauge plug into the rp sensor or is it one of the older models that was hard-wired in?
 
SPEEDSHIFT said:
I would say 80% of the Dipricol gauges I have sold have had issues like this, some go as far as the truck running real rough. Take the harness off the truck, then see if you still have surging. If it continues pull the box off of it, and put a scanner on the truck and read rp via the ecm. You can read what the ecm is asking for, and what it is actually getting with a good scanner.

Does your gauge plug into the rp sensor or is it one of the older models that was hard-wired in?
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Just curious man... any warranty returns? Have they been doing anything to fix them or refund them?

Thanks,
Scott
 
Camotanker said:
Just curious man... any warranty returns? Have they been doing anything to fix them or refund them?

Thanks,
Scott
Click to expand...

Oh yeah, they replaced every single one of them. No problem. It seemed the newer models are fixing the problem. I havent had anyone go through two yet, so I guess they got it figured out.
 
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