68 289 Question - Ford Mustang Forum
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post #1 of 6 (permalink) Old 3 Weeks Ago Thread Starter
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68 289 Question

I need some assistance. I have 68 Mustang with a 289 with a top-end kit on it. It has a FAST EFI as well. My problem is when I get to a light or stop sign or light it dies. It'll start back up but once I push the clutch in to stop it'll cut off again. This was happening before the EFI was installed. A little history about the car, it has been completed restored. All new harnesses, motor rebuilt, etc. Could it not be grounded correctly since the car was painted? I'm at a loss and just can't figure it out. Any assistance is greatly appreciated.

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post #2 of 6 (permalink) Old 3 Weeks Ago
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Well if the problem was both before and after the EFI conversion I'd look elsewhere. Is the idle speed set to low? If you put the car in neutral and start it then depress the clutch will it stall? Is the clutch pedal or linkage hitting a wire somewhere? Does the car stutter when up shifting or is only at a stop?
We will need some more information to get to the bottom of this one.


I'D RATHER GO SLOW THAN NOT GO AT ALL
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post #3 of 6 (permalink) Old 3 Weeks Ago
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It sounds to me that you have a bad engine ground, and the system is somehow only getting adequate ground through the clutch and transmission.

Use a volt-ohm meter and check the resistance between the battery negative and the following points:
  • engine block
  • heads
  • chassis
  • distributor
  • alternator body

All should be zero. If not, find out why. Remove and clean the ground wire connections. Use new lock or serrated washers on bolted connections and wire brush the area to get a paint-free connection. A ground to sheet metal is best when you have a rust-free self-threading screw into a new hole. In an old connection, sometimes you have to drill a slightly larger hole and use the next size screw. For threaded holes, wire brush the bolt and hole to get a clean connection.

After you get the grounds connected permanently then you can paint over them. I like to use CRC marine heavy duty corrosion inhibitor to protect these small areas.

I have a FAST EFI system, and like all of the modern electronics, they need good grounds. On my car, just below the battery, I ended up with an ugly stack of ground connections to the factory chassis ground location, so I installed a marine-grade grounding bus to connect all of the grounds that these systems need. (Bluesea.com, available through Amazon.) I have a #10 wire from this bar to the heads, since I wasn't getting zero resistance between the block and heads.
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post #4 of 6 (permalink) Old 3 Weeks Ago
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I'm with baylensmanfl, The pedal could be snagging a wire under the dash or in the engine bay.

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23/3/1965 289 Manual Fastback.
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post #5 of 6 (permalink) Old 3 Weeks Ago
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It sounds like the same thing that was happening to me and that’s vapor block. But the confusion is the efi should have fixed that. You have a return to on your pump or tank? From what I read gas nowadays the boiling point is much lower.
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post #6 of 6 (permalink) Old 3 Weeks Ago
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Quote:
Originally Posted by Eva67stang View Post
It sounds like the same thing that was happening to me and that’s vapor block. But the confusion is the efi should have fixed that. You have a return to on your pump or tank? From what I read gas nowadays the boiling point is much lower.
EFI systems require high pressure electric fuel pumps either in the tank (easy for a poplar classic like the Mustang) or mounted close to the tank on the lower chassis. This feature eliminates any possibility of vapor lock, which is caused by a mechanical pump drawing from a long suction line.

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