Fuel issue, 98 Cobra w/ Vortech. *Watch Video*

[Stockwell45]

Click on the pic to see video. Does this look like a bad fuel pump to you? New fuel filter, cleaned MAF.

 

[mwolson]

Looks more like a bad fuel pressure gauge sensor to me. I don't think your engine would be running if the fuel pressure were dropping that low.

Is the fuel pressure sensor mounted to the fuel rail? What fuel pressure gauge is that?

 

[Stockwell45]

Its a Vortech gauge, it came with the supercharger kit. It's attached to the fuel rail. The engine dies if I give it any more than a quick pedal push. It was driving great the other day, the gauge was showing 40+ PSI while driving

 

[ZeroDCX]

I wouldn't think the engine would run on pressure readings that low. Can you verify this with another gauge? Was any other work recently performed on the car? It seems as if you've diagnosed your issue though. It should be ~32psi at idle with vacuum source to the FPR and ~42psi without vacuum source to the FPR.

 

[Stockwell45]

I'll try to verify the fuel pressure in the next couple days. It hasn't had any work done to it in the year I've owned it. Even if the gauge was a bit off, I'd still think it's obvious it's not getting enough fuel, for one reason or another.

 

[ZeroDCX]

This is my thinking as well. Are you running the Vortech FMU?

 

[mwolson]

If it isn't running right, there probably is a problem with fuel delivery. I mention the sensor on the fuel rail because Autometer explicitly says not to mount their sensors on the fuel rail. Of course the shop that installed mine put it on the rail, and it failed (reading very low) a couple of years later. It was a $100 charge for the new sensor. So now my sensor is remote mounted to the shock tower.

I am beginning to suspect your fuel pressure regulator, or maybe the fuel pump...

 

[CzchMex]

I have the electric sensor from Autometer on my fuel rail on the Schrader valve. Been on there for a couple years. No issues. But who knows.

You can clearly hear the engine die when the pressure drops. The issue isn't your gauge. I would say the fuel pump is the culprit. A fuel pressure regulator won't cut flow completely - so if that was faulty it would bounce but not to 0.

 

[98 Saleen Cobra]

Hook up a mechanical fuel PSI gauge and see what it reads.. IMO the electrical ones suck.. I had 3 autometer sensors fail on me

 

[mwolson]

The Autometer instructions I read said in bold letters, Do not install the sensor directly on the fuel rail....

Here's how I relocated mine: http://www.classictiger.com/mustang...erRelocation/FuelPressureSenderRelocation.htm