My truck developed a leak from the fuel pressure regulator so I figured what better time to install the blue spring and a fuel pressure gauge so today I did just that. I cycled the key three times then fired the truck up and my isspro gauge is reading about 18 PSI at idle. I drove the truck and at WOT the needles drops slightly to about 16 PSI. I quickly checked for leaks and I do not notice any. I am wondering if something could have gone wrong with the blue spring install that is causing this or would a little bit of air cause this? I think tomorrow I am going to remove the isspro sending unit and install a mechanical gauge to verify the pressure before I go any further.

Has anybody else seen this low of pressure from a 6.0 before?

 

I can't believe it would even run on that.

 

No pinched hoses or bad connection.

 

I would suspect a gauge or sending unit issue at this point. I can't imagine the truck would even start on 18 PSI of fuel pressure. Minimum spec is 40 PSI IIRC.

 

did the brass part have an o-ring on it? was the o-ring facing the right way?

 

Yes there was a o-ring on the brass seat. The o-ring was on there when I took it out of the package so I honestly didn't compare it to my old one and see if it was on the right way.

 

Something has to be wrong with the sending unit or gauge. Try the alternate gauge you suggested to see what you get.

 

I'm hoping its just a gauge issue and my FP isn't actually that low. Hopefully will have time to swap gauges later today. Out of curiosity I removed my tune and the FP is the same.

 

could be gauge. truck cant even start if fuel pressure is really tat low.

 

Yes it can and will start with low PSI like that. The last time my FASS pump went out my wife was driving it and didn't know what the gauge meant ( she knows what they all mean now). She drove it without a fuel pump for 2 days 25+ miles. It wasn't till I got in it to go somewhere (by the way truck was running when I got in it love the remote start) I looked up and saw 0 psi on the gauge. Shut it down and checked. Realized fass pump had quit working. Wife said she saw that gauge at 0 for two days, but thought it was a gauge problem. So these will run without even a pump. Not good on injectors but it will do it. I was lucky enough not to have an injector failure due to this.

 

I once started the truck after a fuel filter change and I had forgotten to tighten the secondary cap down, it was just spun down. 6 psi fuel pressure, diesel every place you could imagine, and the truck was running fine till I turned it off...

Brian

 

Very interesting. I learn something new everyday! Thank u sir!

 

Well I put in a mechanical gauge today and I have 70 PSI at idle so something is up with my new isspro gauge. I have a part number from the sending unit and am going to verify I have the correct one. If it is the correct one then I probably have a faulty sending unit. I know either way isspro will take care of me.

 

Is there an ISSPRo dealer in Canada?
I have the opposite problem with my Fuel Pressure. Was on a road trip & gauge reading normal 55-60PSI. Stopped for fuel & as we drove after that the Press climed to 90-100PSI.
Truck ran fine with no issues till the hotel 100kms away. Pulled filters & they were clean but changed anyway. Press was then 75PSI for a day & now back up to 90-100PSI.
I got home & pulled all filters, good & clean, pulled the blue spring out & checked for debris, clean.

Heading to dealer to have the press tested with mechanical gauge. SO Im hoping its a sensor or gauge. ISSPRO EVII gauge