Engine Engine Cut out about 4000 RPM + Intermittent slow crank

emba129

Member
Jun 10, 2012
17
4
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Hi all,
I took my 93 Cobra out for spirited runs over the last couple of weeks. I experienced the following:

- under hard acceleration the engine would cutout or feel like I was hitting rev limit at around 4000 RPM. It did it about 1/2 the time. Sometimes it would continue to pull past 4K. Its intermittent

- after a long drive, I parked at a restaurant for a couple of hours. When I went to start it is cranked very slowly like the battery was discharged. Its a new battery. On the way home, the charge indicator was reading low 12-13 v estimated. When I got home I measured voltage at the battery with the car running and got 13.5-13.7 v indicating to me that the alternator is charging.

I did a little research and Im thinking:

- alternator/voltage regulator may be intermittent for the low charging issue. Alternator looks original

- fuel pressure regulator or fuel pump for the intermittent cut-out under heavy acceleration at 4000 rpm.

Also, the car feels like it should have more power. My stock 91 Lx 5.0 seems peppier


p.s. I did complete tuneup (new motorcraft plugs, cap, rotors, wires, ignition coil, battery) and timing


Thoughts??
 
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General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
23,748
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Check for codes, and before you say 'no check engine light' you can have codes with trip'n the light.
Next check fuel pressure, vacuum line on and off, also driving, which means you need to see the gauge, you can permanently mount it someplace or temporarily mount it for monitoring and then remove it after.
 

manicmechanic007

5 Year Member
Sep 26, 2017
1,903
537
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Might need a new starter if it is dragging or pulling too many amps
Too much timing causing the problem above 4k rpm?
A good blue point fuel pressure gauge allows for taping it to the windshield (has a real good and long enough hose)
 

Trogdor

Active Member
Aug 30, 2018
64
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I had a similar issue a while back. Turns out I was always getting 12V at the 3rd wire down on the TFI connector. This wire is only supposed to get 12V while cranking. What it does is that it retreads the timing during cranking in order to make it easier.

With the TFI disconnected and key on, test that wire, I think it's pink, and see what voltage you get. Should not be any if the wire is fine. Also you could check the timing with the SPOUT connected and see if it starts retarding while you Rev the engine in neutral.
 
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