1994 Mercury Capri Engine quits at 3000 RPM

Tiny
PLAP
  • MEMBER
  • 1994 MERCURY CAPRI
  • 4 CYL
  • FWD
  • MANUAL
  • 120,000 MILES
1994 Capri 1.6L non-turbo

The engine dies completely at 3000 RPM. As though the ignition is turned off. Revs drop to 2700 and it fires up again on its own (Don't have to hit the starter) Behavior is the same on the road or in neutral parked in the driveway.

When it dies, teh tacho stays alive and follows revs down as the engine spins down.

Start and idle are good. Acceleration is strong without misfire or hesitation, right up to 3000 RPM.

No difference cold or hot.

Problem has just begun. No previous problems.

Around the time it began the car was run out of gas. And refilled. Have changed the fuel filter on the off chance that crud from the bottom of the tank had blocked it. No change.

I have the Ford Power Train Manual and have followed the diagnostic flow chart. There are no fault codes from the engine management system (I am using a VOM to read the codes).

Both the Key On-Engine Off test and the Key On-Engine On tests show no codes. I have tried the Code Erase thinking that might be a computer reset. No change.

Have checked the yellow-Blue wire at the coil and that stays solid 12 V when the engine quits.

Would appreciate any pointers!

Cheers
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Monday, July 7th, 2008 AT 8:06 PM

5 Replies

Tiny
SERVICE WRITER
  • EXPERT
I'll throw in my 2 cents. Might only be worth this, but anyways.

Take off and flip over the air inlet tube to check for splits.

Also, check the crank key way for slop.

Look for bad grounds on the thermostat housing. The bolts holding the housing to the head may have enough corrison that the bracket held on by them that is used as a ground point may not getting a
good ground. If so, remove and clean the bolts and housing.
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Tuesday, July 8th, 2008 AT 5:14 AM
Tiny
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2carpros suggested the items below. Response: No, No and No

Air Tube solid and complete. No cracks
Crank Key has no slop
Ground is good. Measured with low Ohm meter at 0.05 ohm. Bracket and bolts are clean and no corrosion.
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Tuesday, July 8th, 2008 AT 5:28 AM
Tiny
SERVICE WRITER
  • EXPERT
What is the fuel pressure gauge showing for specs from the time it gets up to the stall and back to the re-start?
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Tuesday, July 8th, 2008 AT 6:02 AM
Tiny
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Thanks for the follow on suggestion.

It will take me a little to round up a T-Piece so I can insert the Fuel Pressure Gauge.

Be back when I have done that

Cheers
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Tuesday, July 8th, 2008 AT 3:55 PM
Tiny
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  • MEMBER
Fuel Pressure checks good. Ignition checks good.

Since last post I have taken the car to the dealer and paid out $1000 for them to replace the Throttle Position Sensor and have the computer checked/repaired.

Worked fine for three weeks. The problem has now returned. Car has been back to the dealer and they now say O2 sensor and catalytic convertor. I don't think they know what they are doing.

Car is now running rough, on 3 cyclinders. Starts fine. Idles fine. Cuts out completely at 3000 RPM when cold, 2500 when cold. Restarts on its own when revs drop by 500 RPM.

Still no codes from the computer.

I woudl welcome any other suggestions.
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Wednesday, August 27th, 2008 AT 3:46 PM

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