Looking for some advice. I have a 1999 Cummins Dually. After loosing the lift pump and injector pump over a year ago I put a fuel pressure sensor on the filter filter housing. The gauge always fluctuated erractialy so I never trusted it. I'd frequently see pressures at zero when on the throttle. Truck ran fine. Not trusting the LP I installed an Airdog II and a new pressure gauge from Glow Shift. I've installed the sending unit "T"ed into the fuel line and mounted it on the stock fuel filter that is no longer used with the airdog. I grounded the sending unit to the manifold/filter housing bolts.
The new gauge reads above 13-15psi constantly but spikes above that erratically at times as high as 25-30 which is max. If the sending unit looses ground the gauge will go to 30psi...pegged out. The fluctuation appears to be the result of a fluctuating ground. Checking the continuity between the engine and the battery, from the manifold heater ground wire to battery the Ohms fluctuate while I hear the manifold heater cycle and engine load change with the alternator amp draw. From 1-3ohms to out of range on 200Ohm setting. I cleaned all engine, frame, and body ground. I wouldn't think ohms would change between the engine and battery under amp draw from the heater. To eliminate the ground issue from the engine I grounded the sending unit directly to the battery hoping this would fix this issue.....no change:bang head:
So now I'm assuming I need scubber or needle valve as others have.
The second issue is the check engine light with the install of an Edge Ez module.
Shortly after installing the EZ the check engine light came on.....called ez tech and after trying numerous code resets (P0238) they sent me a new module. With the new module installed I still get the code.
I replace the map sensor and still get the code.....wasted $130.
The code says it's a High Voltage on the map sensor. Code goes away without the edge....Truck runs great on the edge . Tech at EZ thinks the added resistance in adding the module is possibly why the code is being thrown for high voltage....they do pull voltage from the map sensor.
So I'm wandering if the weird ohms readings and fluctuating pressure gauge is also related to why the check engine light is coming on with the Ez module installed.....I can't see two modules being bad. They're ready to send me another module but I don't think it will solve the issue.
Am I the victim of a resistance gremlin?
Any advice would be greatly appreciated.