Weird 1992 Taurus Starting Issue

INDYRJC

MEMBER
1992 FORD TAURUS

I have a really strange starting issue with a 1992 Ford Taurus with standard 3.0 Liter V-6 engine and 130K miles. The car has always run great but last summer developed a problem where it sometimes wouldn't start. Let me backtrack a moment. When the car is starting normally you can turn the ignition key to ON and you will hear the fuel pump in the tank hum for a second as it comes up to pressure. You then turn the key to start and the car starts. Last summer you would turn the ignition on and the RADIATOR COOLING FAN WOULD COME ON while the humming in the fuel tank didn't stop. The engine wouldn't start at all even though it cranked normally. After a while (sometimes a couple of minutes) the cooling fan would finally shut off and the car would start normally. After checking several things (spark and compression were both OK) I finally "fixed" the problem by going to a junkyard and replacing the integrated RELAY CONTROL MODULE (it has a big 24 pin connector going into it) that is mounted on top of the radiator (I replaced the original P/N F1DF-12B581-AA with a F1DF12B577-AA). Everything seemed fine and the car ran fine until last week when the car wouldn't start again. Once again the fan comes on but now won't shut off at all most of the time. On the rare occasions when it does the car starts as it should. Figuring that another junk yard module wouldn't be any better than the one I had I bought a new one from a Ford dealer (F6DZ-12B577-AA is the part number that Ford says is the current replacement). However, the new relay module hasn't helped at all and the car still won't start and the cooling fan comes on whenever the key is turned on. Any ideas? Thanks.

Saturday, January 6th, 2007 AT 10:23 AM

6 Replies

INDYRJC

MEMBER
6 POSTS

BTW, someone suggested that I check out a ground under the window sill plate. Apparently he had experienced some electrical issues when this was dirty on his Taurus. We removed the driver's seat and cleaned this ground but it made no difference. It seemed like a good idea since the starting problem is somewhat intermittent (which does sometimes indicate a bad ground somewhere). Once in a while everything works normally and the car will start. However, when you shut the engine off and try to start it again it goes right back to having the fuel pump hum and the radiator fan come on without starting. Any other ideas out there? Thanks.

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Monday, January 8th, 2007 AT 7:05 PM

INDYRJC

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6 POSTS

Still looking for ideas on this problem. Have gone back and checked (and rechecked) a lot of the connectors that are part of the relay control module. Also loosened and then reconnected the big connector going into the computer. One person has suggested that I consider getting another computer from another car. I'm not sure if this makes any sense or not because once in awhile the car will start normally (although it hasn't for several days now). Any new info on this problem will be appreciated. Thanks.

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Sunday, January 14th, 2007 AT 5:27 PM

SERVICE WRITER

MECHANIC
9,123 POSTS

I'm not sure but will look into it. Those that donate are supposed to get better treatment than you are getting. For that I apologize. I did some searching for some answers. I had some hunches, but they dodn't materialize.

Why re-invent the wheel?

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Sunday, January 14th, 2007 AT 7:33 PM

MATHIASO

MECHANIC
1,209 POSTS

Many intermittent problems are caused by corroded wire connection, bad grounds, loses components.
This situation could indicate a short. I compare this to as pushing on brake pedal and hearing the horn blowing,
What happen here is that you start the car. The fuel pump is working, because you could hear it., But instead of cranking the starter, the cooling fan come on immeditely, why?
To answer to that, get a wiring diagram of your car and a DMM.
A circuit may have may have short to either power or ground.
The difficulty is the second power circuit crosses the first and they are supplying power to each other.
An example of this is when a dual-filament light bulb fails and crosse the brake and parking light circuit. This often results in the dash lights and park lamps coming on whenever the brake is apply.
I'm just giving you few examples so you could figure out.

Keep fighting and do not give up :wink:

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Sunday, January 14th, 2007 AT 10:59 PM

INDYRJC

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6 POSTS

It does sound like the same kind of problem; but not quite. If I read everything correctly (it went on forever) they ended up finding a bad diode in the relay control module which I have replaced a couple of times (one from a junkyard and one new one from a Ford dealer that's on the car now). It seems like there's something else going on.

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Monday, January 15th, 2007 AT 2:22 PM

INDYRJC

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6 POSTS

I went out this morning and lo and behold the car started just like it was supposed to. You could hear the hum in the fuel tank for a second followed by a relay click under the hood (in the relay control module) and the car would start. In spite of this I went over all of the connectors in the vicinity of the (removed) air cleaner and checked them for corrosion or bad connections. I had also noticed in the link that was provided (on a '97 Taurus) that someone recommended looking into the Coolant Temperature Sensor Circuit since this would be what tells the cooling fan to come on. Because of this I went ahead and replaced the Coolant Temp Sensor (not the sender) with a new one. Now the car will start many times in a row and only once in a great while will the fan come on without the car starting. I also noticed that one time when the engine was running it suddenly died and I could hear the fan come on again. That's the first time I have noticed that the fan coming on apparently out of sequence could actually make the engine stop. I'm not sure what to make of it but is this a clue that means something to someone here? For now, at least, the car is starting the majority of the time. But there's still something not quite right here. If anyone has any other ideas I'm open to just about anything. Thanks.

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Saturday, January 20th, 2007 AT 3:16 PM