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2001 Cobra No Start

Ether is much more flammable than gasoline. If it lit off ether but not gas could be an indication of a weak spark condition.
 
With it hitting on starting fluid, it tells me I have spark but no fuel.

- I have fuel pressure at the shrader valve at the rail.
- I verified voltage at the injector harness and a grounding pulse during cranking on the other wire.

I don’t have a noid light but shouldn’t these tests prove the injector harness out?


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Injectors are pulsing as well.

To recap: Fuel pressure at rails, injector pulse, have spark, will hit on ether. Seems I have all the recipe for ignition. Even if the timing was completely off, I’d at least hit or backfire. I’m getting none of that.

Anyone got any suggestions? I’m lost as my next steps. I’ll grab some fresh plugs but don’t think that’s gonna change anything.


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I still think you have timing off and/or weak spark. It is VERY easy to fire off ether. Gasoline not so much. Since the timing is all electronically controlled (as far as my brain knows) if you have the right signal and you have the valve timing correct low voltage to the ignition system seems the logical cause.
 
Horseplay said:
I still think you have timing off and/or weak spark. It is VERY easy to fire off ether. Gasoline not so much. Since the timing is all electronically controlled (as far as my brain knows) if you have the right signal and you have the valve timing correct low voltage to the ignition system seems the logical cause.
Click to expand...

Conducted a compression test and 180-190 PSI on all cylinders, so timing has to be correct.

I sprayed gas in the intake and it fires that way as well. Clearly a fuel delivery issue.

Put 5 gallon of fresh gas in and used some to “prime” the throttle body with. It fires and runs off that fuel.

Made everything normal and it’s now trying to hit.


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Is anyone still reading this? lol

Still fighting issues. Got it running after cleaning the IAC.

Fuel pressure at the shrader is 55-60 psi, which I think is too high. It will start then kinda stalls out after a bit. Finally got it to run long enough to throw a code. P0190, which points to the FRPS. Unplugged that and the car starts and runs but is pig rich. As soon as I plug the FRPS in, engine stalls out. I have a new FRPS coming Monday.

I need to get Forscan so I can monitor this thing apparently.


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I'm reading it. Following it? Not so much. I've purposely only allowed myself to understand all the modern engine control stuff minimally. Enough to have a basic understanding of how it all functions. Deep diagnostics and troubleshooting are beyond me on that crap. My brain is deep into 40's/50's hot rod now. The more hand made and primitive the better. I'll get back into the new stuff once I get this coupe done and I am back on the truck project.

So keep posting and I'll keep reading. It is interesting and educational for some of us.
 
I have a thread going here called 2001 Cobra No Start. Thought I would bring this question out to get more views and thoughts.

Stock fuel pump that I changed 10 months ago, stock tune to my knowledge. Fresh 03 heads with 96-98 cams, but other than that engine is stock with EGR and everything.

Issue- key on fuel pressure is 50 PSI.
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To get the car to fire, I have to unplug the FRP sensor. I changed it to a new one with the same result.

When running, fuel pressure is 45-50. I haven’t let the car warm up to see what it settles down to because I’m scared to run it long without the FRP sensor.

Attaching video of pressure and how it dies immediately when the FRP sensor is plugged in.



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f6b14e0a41fe29c18a16731e41d3c0ae.jpg

I think I might be on to something. I thought I would verify continuity on this connector.

VREF on plug is pin 90 at the PCM. I am getting a 2.6k short when I test continuity.

SIG RTN to pin 91 gives a solid short

FRP to pin 63 gives a solid short.

Question, should VREF have High resistance? According to what I’m seeing it has a resistor inline.

I did verify FRP is correct at 5V.


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Got it figured out with the help of some folks at SVTPerformance.com. It was the VREF. When repairing the harness I “fixed” what I thought was a chewed/melted wire. It was in fact a factory union. I broke the bonding of the wires, therefore was missing the correct 5v at the VREF of the FRP sensor. Correcting the wire and boom, fires every time.


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