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Discussion Starter · #1 ·
I am working on a 1990 Mercury Sable. with 3.8 liter V6, for my elderly mother in law. The car ran fine. It leaked coolant, so I suspected a head gasket. Years ago I fixed my ’90 tbird with the same engine same problem. After reassembly, the car started, but ran very poorly, and very rich, with black smoke. The engine would not rev over 4000 rpm. I thought the injectors were not working. After testing resistance and voltage I found they were. I changed the fuel pressure regulator, then the car would not start at all. It tries to start, almost, like the timing is off. I did not move the distributor during my gasket replacement. I live about 200 miles away and work on it once a month or so. I want to get it running as it was before the change, I am lost at what may be wrong. Any ideas would be welcome. Thank you in advance. [email protected]
 

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Check the vacuum & electrical connections to the MAP sensor on the firewall.
 
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Discussion Starter · #4 · (Edited)
sable saga continues

Was able to work on the 90 sable this weekend, got it running after I primed the fuel pump. Ran better after I changed the cap and rotor. Ran rough and smoked black, and the cc turned red hot while I was running at 3K rpm. The weeds under the car started to smoke, scary...
I drove it a bit and it seemed to improve. Idles rough, surges or dies. Next time I will drain the gas, several months old, and with fresh gas, injector cleaner, and maybe a fuel filter change. I changed the O2 sensor early on, may need a fresh one. Is there a way to clean them? Any other suggestions? Thanks, Earl
 

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Is the CEL lit???? If so, scan the computer for trouble codes & post all of the code Numbers found, as they can offer up good trouble shooting clues.

Is the electrical connector & vacuum line to the MAP sensor ok & hooked up????

Have you checked fuel pressure at the fuel rail schrader valve test port???

Have you pulled the fuel pressure regulator vacuum line & checked to see if it's wet with fuel inside??? If it is, the pressure regulators diaphragm is ruptured & leaking unmetered fuel into the intake manafold via the vacuum line & this will make it run rich, as will too high a fuel pressure value.

More thoughts for consideration, keep us posted on your findings.
 

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Discussion Starter · #6 · (Edited)
sable saga continues

The CEL is lit most of the time, goes off while it is running, for short times. How do I pull the error codes on a '90? I have a obd2, is there another way? I rechecked all the connections, and the fpr is new, and the vac line is dry. I tested the fuel pressure, it was fine at 40 psi.

I will try again in 3 weeks, wish me luck.

Thanks, Earl
 

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The CEL is lit most of the time, goes off while it is running, for short times. How do I pull the error codes on a '90? I have a obd2, is there another way? I rechecked all the connections, and the fpr is new, and the vac line is dry. I tested the fuel pressure, it was fine at 40 psi.

I will try again in 3 weeks, wish me luck.

Thanks, Earl
OBD1 code reader goes back to the 80s. You will need a ford specific cable since each manufacturer had different hook ups. OBD1 is pretty generic but will give you some clues as to what's going on.

So did you confirm a head gasket leak with a combustion gas detection kit or have any signs of head gasket failure like milky oil or did you just assume it was head gasket? Did you have the heads serviced when you did the job or just put new gasket in?

Black smoke usually means fuel mixture not right for some reason, not enough air or to much fuel. How is the air filter? Three sensors to check is mass airflow sensor, throttle position sensor, and coolant temp sensor, these can all effect the cars fuel mixture. Wouldn't hurt to clean the throttle body also to make sure the plate isn't stuck closed blocking air.

Take the car to auto parts store and have them read the codes and clear them, might be some old codes stored so clear them and then see which ones come back. Or buy an OBD1 reader, they can be found for fairly cheap since they are almost obsolete. You need to try and figure out what's wrong before just throwing parts at it and costing your MIL lots of money on a 21 year old car.
 

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The CEL is lit most of the time, goes off while it is running, for short times. How do I pull the error codes on a '90? I have a obd2, is there another way? I rechecked all the connections, and the fpr is new, and the vac line is dry. I tested the fuel pressure, it was fine at 40 psi.

I will try again in 3 weeks, wish me luck.

Thanks, Earl
Here is how to extract DTC's on your OBD-1 emissions system, if you don't have a code reader, santool, or your autoparts store doesn't use one that will.
With a jumper wire in the right place, you can cause the vehicles CEL to blink the trouble codes, or you can use a 12 volt test light, or an analog multimeter on the 20 volt DC scale & count it's meter movements.

The connector on your Taurus in under hood, passenger side, attached to a piece of black plastic trim at the firewall.

Ford Fuel Injection How To Run a Self-Test Let us know the code Number/s you extract.
 

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the cat turning red is a good sign that it is clogged or the engine is dumping gas into the cat. either way the cat is going to be bad. have you tried spraying stater fluid to check for a vac leak?
 

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Discussion Starter · #11 ·
Still no success

Had high hopes with the obd1 reader. Plugged it in-no output. Ran the car with CEL on, checked again, no output. Tried the ether spray trick, no change. Still runs rough and smokes black. Circumstances this weekend did not allow me to change the gas out like I planned. Am dismissing that as I have 10 gallons of new gas mixed in, with gas treatment. Gas is not causing the problems I am seeing.Will try to find a local mechanic that will fix the car without charging me more than it is worth. Thanks for the support.
 

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Pull the vacuum line to the fuel pressure regulator, (located under hood on the fuel rail) & see if it's wet with fuel, if so the regulators diaphragm is ruptured, so replace the regulator.

If thats ok, check the fuel pressure at the fuel rail schrader valve test port.

If thats ok, make sure the MAP sensor is hooked up right & it's electrical connections are good.

Did you try the link I posted on how to pull the trouble codes without a code reader???? If you still can't extract codes, maybe suspect the computer.
 

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Discussion Starter · #13 ·
Tried the 1st 3, will try the test light in 3 weeks.

What is the best way to empty the gas tank? Siphon would not work, something in the filler that blocks the hose. Thanks!

Earl
 

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Maybe you "might" change the fuel filter? So it idles at 40psi fuel pressure - what happens when the car is accelerating? Change the fuel filter, as that should have been the first thing you would do. This is basic maintenance and is almost never a waste of time or money.
 
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