1987 5.0 Stalls at Idle.

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Someone will be along shortly with advice.

1950FordJerry said:

My 1987 fuel injected 5.0 (installed in my 1950 Ford 2dr) has been running great for a long time. I haven't driven it in about a year, as the engine will just die in traffic. It will usually restart after a minute or two. It is not overheated, it will stall sometimes before the electric fan kicks on. I'm curious if anyone knows what could cause this to happen?
I live in Va Beach, VA and do not know of any mobile Ford mechanics that could come by and diagnose/fix it, so i thought someone on this Forum may have encountered this same problem.
Cooler weather is coming and i want to be able to drive my 50' again. Let me know if you can offer assistance.

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Does it only stall when the motor is warmed up to operating temperature? Does it stall more than once while driving it? Almost sounds like the ignition control module on the distributor. This link is a good read with testing procedures

Ford EEC-IV/TFI-IV Electronic Engine Control Troubleshooting

my89foxbody said:

Does it only stall when the motor is warmed up to operating temperature? Does it stall more than once while driving it? Almost sounds like the ignition control module on the distributor. This link is a good read with testing procedures

Ford EEC-IV/TFI-IV Electronic Engine Control Troubleshooting

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Thank you, that's a good question. When i stopped driving it, i lived about 8 minutes from my office, it would typically die once half way there, and a couple of times it died right when i pulled into the parking lot. Same thing going home.
Just last weekend, i started it and it ran fine and idled. Suddenly it shut off. I restarted no problem, it ran about 5 minutes and stalled again. It did this two more times and then the engine fan came on, so i know not to run it standing still with just the fan, as it does not move enough air.
I did replace that distributor module about 2-3 years ago, still think that may be the issue?

The PIP sensor and TFI module are the common ignition killers in the old small block fuel injected 5.0. When the TFI module starts to fail it's known to give starting problems when it gets hot. As I recall a failing PIP sensor will also give problems when it gets hot but it will stall out a running engine rather than keep it from starting. I've read that these parts can fail pretty quickly so 2-3 years mean little in life expectancy.
Your problem could be ignition or fuel related but I would stray towards ignition.

1950FordJerry said:

Thank you, that's a good question. When i stopped driving it, i lived about 8 minutes from my office, it would typically die once half way there, and a couple of times it died right when i pulled into the parking lot. Same thing going home.
Just last weekend, i started it and it ran fine and idled. Suddenly it shut off. I restarted no problem, it ran about 5 minutes and stalled again. It did this two more times and then the engine fan came on, so i know not to run it standing still with just the fan, as it does not move enough air.
I did replace that distributor module about 2-3 years ago, still think that may be the issue?

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I would look at that link so you could do some testing to determine which is the issue

Cobrajet67 said:

The PIP sensor and TFI module are the common ignition killers in the old small block fuel injected 5.0. When the TFI module starts to fail it's known to give starting problems when it gets hot. As I recall a failing PIP sensor will also give problems when it gets hot but it will stall out a running engine rather than keep it from starting. I've read that these parts can fail pretty quickly so 2-3 years mean little in life expectancy.
Your problem could be ignition or fuel related but I would stray towards ignition.

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Thank you, that is great advice from both respondents. I did replace the TFI module about 2-3 years ago. I don't know where the PIP sensor is, but i will find it and replace it first.
Thank you again, this has been most helpful.

Cheap aftermarket parts will fail so the new TFI module is still a likely suspect.
The PIP is inside the distributor and requires disassembling the distributor to get at it. It's easier to just replace the distributor with a new one.
If it won't start you should check for spark and injector pulse. If you have neither then that means it might be the PIP. The PIP will be functioing if you have injector pulse.
The ECM relay or a bad ECM ground can also cause your problem.
If you have an OBD 1 capable scanner then you should see what code(s) you have. If not, you can do the KOEO self test.

Cobrajet67 said:

Cheap aftermarket parts will fail so the new TFI module is still a likely suspect.
The PIP is inside the distributor and requires disassembling the distributor to get at it. It's easier to just replace the distributor with a new one.
If it won't start you should check for spark and injector pulse. If you have neither then that means it might be the PIP. The PIP will be functioing if you have injector pulse.
The ECM relay or a bad ECM ground can also cause your problem.
If you have an OBD 1 capable scanner then you should see what code(s) you have. If not, you can do the KOEO self test.

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Thank you, i do have OBD 1; it's rather primitive, but i will give it shot. I did order a new TFI and will install that first. i suspected the in tank fuel pump could also be a problem.

Roachwe said:

I would hook up a fuel pressure gauge while driving just to rule out a faulty fuel pump.

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Thanks so much, that's plan B; replace the in tank fuel pump as sometimes the straitor valve on the fuel rail has no gas in it and other times you get a strong spurt; i would think it should be charged all the time. I can hear the fuel pump engage before i start engine, but that doesn't mean it doesn't fail intermittently.

my89foxbody said:

I would look at that link so you could do some testing to determine which is the issue

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Thank you, i have looked at it and printed the instructions.

1950FordJerry said:

the straitor valve on the fuel rail has no gas in it and other times you get a strong spurt; i would think it should be charged all the time. I can hear the fuel pump engage before i start engine, but that doesn't mean it doesn't fail intermittently.

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I assume that you mean the Schrader valve?
The fuel rail will depressurize over time as it sits. I would think that a return type of system like the Fox body has would be quicker to lose pressure after it sits for a while than the returnless systems that newer cars have.
If you don't have pressure when you turn the key to ignition then that is a problem. Since you hear the pump prime it could be that the pump itself is weak or it could be the FPR(fuel pressure regulator) is the source of the problem.
Instead of throwing parts at it and wasting any more time and $ you should scan the car or get the code from the KOEO self test. All 1987-93 Mustangs were OBD 1 so if you know someone who has a scanner that's OBD 1 capable or go to a large chain auto parts store that uses a higher end scanner to scan customer's cars it can retrieve the code.

Cobrajet67 said:

I assume that you mean the Schrader valve?
The fuel rail will depressurize over time as it sits. I would think that a return type of system like the Fox body has would be quicker to lose pressure after it sits for a while than the returnless systems that newer cars have.
If you don't have pressure when you turn the key to ignition then that is a problem. Since you hear the pump prime it could be that the pump itself is weak or it could be the FPR(fuel pressure regulator) is the source of the problem.
Instead of throwing parts at it and wasting any more time and $ you should scan the car or get the code from the KOEO self test. All 1987-93 Mustangs were OBD 1 so if you know someone who has a scanner that's OBD 1 capable or go to a large chain auto parts store that uses a higher end scanner to scan customer's cars it can retrieve the code.

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Thank you, i know i spelled that wrong and spell check did not help me out. I do have an OBD 1 and code book, and will run the scan this weekend to see what codes come up. Thanks again, this forum has been very helpful.

Heres what I would check....Pin #4 coming from the ECU plug to pin #2 on the TFI plug.....Theres supposed to be a 22kohm resistor installed by the connector...On my Fraud Francis harness TDZ-75 they hooked-up all of the ground wires together and that caused mega running issues after an hour of driving like erratic idle...

If your wire harness is from an automatic converted to 5 speed and youre still running the CCD ignition module it will give issues..I run the ACCEL #35369 and the Jegs #4606..

If its an original 5 speed harness and the resistor failed it will cause issues too and when the resistor fails they fail to "OPEN" giving the IDM circuit unfiltered power wreaking havoc on your TFI module, coil and computer so if it reads 0.00kohms on a 200kohm setting you need to replace the old resistor or add one to the harness as theres been lots of 5 speed harnesses missing resistors from the factory........

You should also be running a non CCD module...As you can see the myth about module color is just that..A Myth....They can come in either color...The difference in both is the weight.........The non-ccd module is heavier than the CCD one...

Another thing Id do is replace the EEC relay with a diode protected one especially if the relay looks original as they start losing its power transferring resilience after 8-10 years plus the fuel pump relay is powered by the ECU relay too as circuits #37 and #57 and 12v reference wires aswell as power for the ECU from the EEC relay and it needs to see the same voltage as the battery..Once the internal contact gets oxidized or carbonized it becomes less effective which leads to lots of issues especially with the MAF sensor.....

I would also go over how you grounded the ECU as the EEC-IV ECU is very finicky as to how its grounded because it uses a three wire grounding system where two of them grounds need to be as clean as possible so the ground with the circuitry can be gauged against the one without the circuitry..

Your ECU should be grounded like this illustration above........In a Mustang GT the wires are attached to the unibody behind the battery and the EEC relay grounded to the core support.........

What it doesnt show is that the 02 sensors are grounded to the cylinder head..

In a truck like yours Id run the grounds to the firewall right next to the battery and hook the battery pigtail to the ECU grounding point..........

I have mine grounded to a custom built grounding system that filters out the EMI radiation the alternator produces..........

Awesome information CamTwo! Thanks so much for the detail. I will print out this information to have a hand. It did start this weekend and only stalled once, but it had not yet warmed up enough for the electric fan to kick on, that's when it will stall the most.

Thanks again, very much appreciated.

You are Welcome 1950FordJerry...

Heres info no-one realizes about the ways a resistor can fail and thats the fact that Age and overvoltages from improper jumpstarting will cause the 22k resistor to fail....

I was always taught when jumpstarting a vehicle you put positive to positive and negative to negative.....

I was also taught that after the vehicle being jumped starts its imperative to quickly remove the cables to prevent damage to the alternator of the vehicle that gave the jump but thats not entirely true or accurate I found out about 16yrs ago how to jumpstart a vehicle the right way....

I found out that on the vehicle with the dead battery you want to attach the negative clamp to the alternator;-not the battery negative.

I also found out that after the vehicle being jumpstarted starts up you should wait a minimal of 3 mins before removing the jumpstarter clamps to prevent powersurges from when the alternator sees a huge voltage and amperage drop and instantly tries to catch it quick..

If the vehicle wont start using the method above means you have a deficient grounding path between the battery and the alternator......

Theres a really easy way to tell using a multimeter if your ground is good enough.....

Start vehicle and take off radiator cap and grab a multimeter..Put the meter on the lowest DC voltage setting...

Put the Negative probe on the battery Negative and the Positive probe into the radiator solution and read the electrolysis voltage....

If you get a reading higher than .3volts at idle or when all of the accessories are turned on you need a better ground to the battery also some sacrificial Anode Rods too especially if you have aluminum heads and/or intake as electrolysis eats them up and the sacrificial Anode rods give the electrolysis running through your system something else to eat other than your intake , heads , aluminum waterpump , solder joints in the heater core and errosion to the aluminum radiator cores...............

On my Edelbrock intake #3881 theres two screw ports at the rear of the intake on both sides that look like water sensor ports...Thats where I put my magnesium anode rods......

Good Luck.....

No problem Jerry...

Also you mentioned that the truck stalls more when the electric fans come on.......

That tells me that the voltage draw the fans are drawing is taking away from the ECU's way to operate and thats through the ECU relay or the 12v main power wire that feeds the relay and powers the ECU...If its original or older than 10yrs old replace it with a new one thats diode protected....

As you can see from this schematic mini clip the EEC relay is powered and grounded in a very specific way and thats direct to the battery...

When I wire my electric fans I hook the positive to the battery direct using a 40-60 amp maxi fuse and use the relay or relays to control the negative wire or wires as the trigger depending on whether 1 or two fans .....

This eliminates a heavy power draw through the small relay contact and allows full power to flow through your fan motor or motors....

I ground the ground wire to the relay on one side and on the other side I ground it to the frame....

Another tip after you go over your grounds and power is this....

Start the truck with the IAC unplugged and the Spout disconnected...

Take a timing light and set timing to 10* BTDC.

Set lowest idle speed the engine will still run using the t-stop screw.

Take a multimeter and do a probe of the green and black wires coming from the TPS to see if the voltage falls between .96 and .98/.99 volts...If not adjust the TPS until you get the voltage in this range as its optimal to how the EEC system works...

Shut the engine down and reconnect the IAC and the Spout connector then drain down the ECU...

I find disconnecting the Positive cable then holding your foot on the brake with the ignition key turned to the start position for about a minute totally drains the ECUs internal capacitors....

Reattach the battery and start the truck...after 2 mins of idling turn on all of the accessories and put the max load that the vehicle will see on the system for 2 mins..

After 2 mins under a heavy load turn off the load and shut the truck off for 2 mins....

After 2 mins restart your truck and take on an easy 10 mile ride to set the fuel trim economy...

Good Luck

camtwo1970 said:

No problem Jerry...

Also you mentioned that the truck stalls more when the electric fans come on.......

That tells me that the voltage draw the fans are drawing is taking away from the ECU's way to operate and thats through the ECU relay or the 12v main power wire that feeds the relay and powers the ECU...If its original or older than 10yrs old replace it with a new one thats diode protected....

As you can see from this schematic mini clip the EEC relay is powered and grounded in a very specific way and thats direct to the battery...

View attachment 788532

When I wire my electric fans I hook the positive to the battery direct using a 40-60 amp maxi fuse and use the relay or relays to control the negative wire or wires as the trigger depending on whether 1 or two fans .....

This eliminates a heavy power draw through the small relay contact and allows full power to flow through your fan motor or motors....

I ground the ground wire to the relay on one side and on the other side I ground it to the frame....

Another tip after you go over your grounds and power is this....

Start the truck with the IAC unplugged and the Spout disconnected...

Take a timing light and set timing to 10* BTDC.

Set lowest idle speed the engine will still run using the t-stop screw.

Take a multimeter and do a probe of the green and black wires coming from the TPS to see if the voltage falls between .96 and .98/.99 volts...If not adjust the TPS until you get the voltage in this range as its optimal to how the EEC system works...

Shut the engine down and reconnect the IAC and the Spout connector then drain down the ECU...

I find disconnecting the Positive cable then holding your foot on the brake with the ignition key turned to the start position for about a minute totally drains the ECUs internal capacitors....

Reattach the battery and start the truck...after 2 mins of idling turn on all of the accessories and put the max load that the vehicle will see on the system for 2 mins..

After 2 mins under a heavy load turn off the load and shut the truck off for 2 mins....

After 2 mins restart your truck and take on an easy 10 mile ride to set the fuel trim economy...

Good Luck

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Awesome info CamTwo, thank you again for your help. I should have just towed my 50' Ford over to your house

1950FordJerry said:

Awesome info CamTwo, thank you again for your help. I should have just towed my 50' Ford over to your house

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That would be A-OK with me & Not a Problem....!

Best part is not only will your vehicle run killer but you'll be more in-depth with it also the payment of services are simply some sugar free Monsters.Maybe some lunch .....LOL

And definately a cruise in that 50 when finished and running killer too........!!

Take care and Good Luck nailing down and solving the issue..

camtwo1970 said:

That would be A-OK with me & Not a Problem....!

Best part is not only will your vehicle run killer but you'll be more in-depth with it also the payment of services are simply some sugar free Monsters.Maybe some lunch .....LOL

And definately a cruise in that 50 when finished and running killer too........!!

Take care and Good Luck nailing down and solving the issue..

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thanks so much, sorry for late reply, have family in town for Thanksgiving and hunting season just opened