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Discussion Starter #1 (Edited)
Wife barley made it home tonight.

Shaking bad, acting like she is starving for gas. I borrowed a fuel pressure gauge & she sits at 30psi idling. Then only goes up about 2 psi when you give it the throttle. Then quickly drops back down. Checked all the vacuum hoses and everything looks great. Nothing has changed, just acted up out of the blue today.

I installed Motorcraft platinum spark plugs & new Motorcraft wires about 4 years ago.

I replaced the fuel filter last year (maintance) maybe 12k miles ago (if that).

Father-in-law had to put an aftermarket fuel pump in it about 6 years ago.


Any best guesses guys??
 

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Fig. Fig. 2 Testing the primary ignition coil resistance-4.6L engine
  1. Turn the ignition OFF .
  2. Disconnect the negative battery cable.
  3. Disconnect the wiring harness from the ignition coil.
  4. Check for dirt, corrosion or damage on the terminals and repair as necessary.
  5. Measure coil primary resistance between ignition coil pin 2 (B+) and pins 1 (coil 2), 2 (coil 3) and 3 (coil 1).
  6. Resistance should be 0.3-1.0 ohms. If resistance is out of specifications, replace the coil pack. If resistance is within specifications, proceed to secondary windings testing.
    1. Measure coil secondary resistance between the corresponding spark plug wire towers on the coil.


    Coil 1-cylinders 1 and 6 Coil 2-cylinders 3 and 5 Coil 3-cylinders 4 and 7 Coil 4-cylinders 2 and 8
    1. Resistance should be 12.8-13.1 kilohms. If secondary resistance is not within specification, replace the coil pack
 

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30-45 PSI (Pounds per Square Inch)Attach fuel pressure gauge test valve as to releasethe pressure in the fuel system, then place the openhose end into a suitable gasoline container. Nowproceed to bleed down the pressurized fuel system.Close the test gauge valve and place the ignitionin the on position, utilize a scan tool to energizethe fuel pump.This will bring the system to a stabilized fuelpressure that can be visually verified on the gauge
 

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Discussion Starter #4
Thanks for the reply Dom, I'll run the coil test & that fuel pressure test tomorrow night...
 

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fuel pressure should be 39 lbs @ idle.

Wife barley made it home tonight.

Shaking bad, acting like she is starving for gas. I borrowed a fuel pressure gauge & she sits at 30psi idling. Then only goes up about 2 psi when you give it the throttle. Then quickly drops back down. Checked all the vacuum hoses and everything looks great. Nothing has changed, just acted up out of the blue today.

I installed Motorcraft platinum spark plugs & new Motorcraft wires about 4 years ago.

I replaced the fuel filter last year (maintance) maybe 12k miles ago (if that).

Father-in-law had to put an aftermarket fuel pump in it about 6 years ago.


Any best guesses guys??
 

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Discussion Starter #7
I ran the fuel pressure test again & at "key on", and 28lbs was all she wrote.

I didn't have time to run the coil pack test yet. By the time I got home from work, ran this one test, & was reminded of the wife's Sensy Party (I'd forgotten about), I had to watch our 3 & 5 y/o girls, so my evening was shot.

Tonight we have church so I'm going to "take a break" before I yank the tank. I bought a replacment "Delphi" pump instead of a Motorcraft. It also offers a lifetime warranty & was mid-level priced compaired to the cheeper in-house brands around this town.

What do you think about a replacement Delphi unit guys? It looked very nice & very similiar- When compared to the Motorcraft one, less the smaller filter/sock on the bottom.
 

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As long as you bought the complete unit and not one of hose pump only ones
you should be OK.
I had to Put a Carter complete assy on my old Bird and it's been over 4 years now
It was around 180.00
 

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Discussion Starter #10
Am I correct to say that the secondary coil test is done with the coil installed back onto the vehicle, everything plugged back in- including the neg.battery cable?
 

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I think you leave it disconnected

Measure the coil secondary resistance. Connect the ohmmeter's black lead to the coil's negative (-) electrical connector and the ohmmeter's red lead to the coil's terminal-where the distributor or spark plug wire attaches to. A typical resistance reading could be 8,000 to 11,500 ohms.
  • 8
    Replace the coil if any of the readings for your particular coil is bellow or above the specifications indicated in your service manual.
  • 9
    Reinstall the coil, electrical connector, wires and connect the negative cable to the battery terminal
 

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Discussion Starter #12
But the pic above (in your original reply above), for the 2ndary test shows the probs going into opposite spark plug holes or "wire towers" as it describes them??

Which pin on the coil is the negative lead? Neither my stock Ford coil nor the hard shell wiring connector label the pins?
 

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Discussion Starter #14 (Edited)
Okay, I figured the secondary test out. Our drivers side coil pack passed the primary test (0.5 & 0.5 ohms) but failed the 2nd test (13.4 & 13.5 kilohms).

So I purchased a new coil.

SUV still shudders & feels like its missing under throttle.

I still need to test the 2nd ignition coil (tomorrow), but come on, low fuel pressure & both coils failing at the same time??

Sounds fishy to me... =(
 

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Have you thought about a plugged convertor?
Inspect/Test
Often leaks and rattles are the only things looked for in an exhaust system. The exhaust system should also be tested for blockage and restrictions. Collapsed pipes or clogged converters and/of mufflers can cause these blockages.
There are many ways to check for a restricted exhaust. The most common of these is the use of a vacuum gauge.
  • Connect a vacuum gauge to an intake manifold vacuum source. Bring the engine to a moderate speed and hold it there.
  • Watch the vacuum gauge.
  • It should indicate a vacuum of 16-20 in. of mercury.
  • Increase the engine's speed to 2000 rpm and observe the vacuum gauge. Vacuum will decrease when the speed is increased rapidly, but it should stabilize at 16-21 in. of mercury and remain constant.
  • If the vacuum does not build up to at least the idle reading, the exhaust system is restircted or blocked
 

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Discussion Starter #17
Will an old '99 store codes without an illuminated SES light too??
 

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My old 91 stored the code for an intermediate light that would come on and off.
Had to replace one of the front EGO sensors and then later on I burnt out A PFE sensor so I know I'll have to replace a convertor one of theses days
 

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Discussion Starter #19
2nd coil pack on, same problem.

I drove for a while tonight. Never an SES light. O'reillys & Autozone scanners could not pull any trouble codes....
 

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Man I have read about all the engine management parts
they most all say may set off a light.
Note the may.
Just for kicks don't buy anything.
Look at your electrical connection to your crankshaft sensor and or grime on the
exciter ring to see if something hit them from the road or weather condition,
look at your DPFE for signs of melting.
When you replaced the fuel pump did you replace the filter?
You may try pulling the front EGO sensor out and see if the power picks up
or you could drill a hole in front of the convertor and then plug it up with a screw.
You may have to bite the bullet and have Ford analize it for you:(
You have spent a good deal of money on it now.
Let me know
 
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