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91 TBI 350 Shuts down when hot but will start after cooling for a few minutes

JPOutfitters

JPOutfitters

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I'm fighting an issue I found while driving back from Nebraska to Colorado Springs, CO a couple of weeks ago. Temps outside were upper 90s-low100s and it would just die like it ran out of fuel suddenly. I would coast to the side of the highway and let it sit for about 5 minutes and it would start right up and cruise down the highway for another 15-20 minutes and shut down again. It was late on a Sunday afternoon and no parts stores around so I literally kept going until it shutdown and then let it sit for a few minutes and pushed it again. Once I got to Denver on I70 and hit I25 heading south I stopped for some food in a grocery store for about an hour and was able to drive the rest of the way home without any issues.

It has been running perfect around town since and I've noticed that since it hasn't really been too hot lately that that may be the cause. Today, however, it died on me again. I replaced the fuel pump relay and it fired right up and ran great. After about 30 minutes of driving stop and go traffic in Colorado Springs it did it again!

So I spent the better part of the evening going through scenarios.....

I start it and let it idle until it dies. I turn off the key and wait 10 seconds and when I turn the key on, I can hear the fuel pump cycle so I know the fuel pump is working right after it shuts down. I replaced the fuel pump and fuel filter 2 years ago and now the fuel pump relay today.

I also made note that I had 55-60psi oil pressure when it shut down so I know it's not the oil pressure switch shutting me down.

I'm not getting any codes except the regular "12" code so I have no idea what's going on!

Will the coil shut me down if it gets hot and then work when it cools off?

Will the Ignition Control Module inside of the distributor shut me down if it gets hot and then work when it cools off?

It has been working normally without any problems driving for 20-30 minutes......but if I drive longer than that without shutting it off it starts to die and cause me this grief whether sitting at an idle or driving down the road at speed...........HELP!:eek1::eek1::eek1::eek1::eek1:
 
JPOutfitters said:
Will this shut it down?
Click to expand...

Probably not if the check engine light isn't on. If you can check what its reading, it could at least tell you if the engine temp is related.

Ignition module is also a possibility and would definitely shut it down.

-Brian
 
yup, very common failure for them to stop working when they get hot... usually when it happens, it just up and quits..
 
Yep, it sounds electronic. I'd go with the ignition module. Quitting when hot is a real common failure scenario for electronics.
I have seen coils do it too. Usually that is because it was should have had a resistor and didn't.
Not your problem, of course, but the symptoms were the same.

I would swap the ignition module, being sure to use the heat sink compound when you put on the new one.

Fords with the old duraspark module on the fender would do it.
I drove from Panama City to Orlando one day using little baggies of ice.
When it quit just outside of town on a Sunday afternoon, I popped the hood and let it cool down.
Made it to the local equivalent of a 7-11, bought a couple bags of ice and some small sandwich bags.

Threw the ice in the cooler I always had in the back, put a small amount of ice in the baggie and laid it on the module.
Then wrapped it up good with a blanket, taped it down with some duct tape and took off.
Got about 70 miles.

Next time, I took it off the fender, put two baggies on, one under and one on top and wrapped it completely up in the blanket.
It did not have to be grounded, and the fender was letting heat get to it from underneath.
That lasted until my one and only gas/milkshake stop. I redid it, and made it to my apartment in Orlando.
Rode my bike to class, hitched a ride to a parts store and got the module.
No core, so I kept the old one in the trunk.
It would get me a few miles if the new one quit completely.

When I gave the car away years later, the guy I gave it to found the module and put it in his hunting truck.
Got way the heck on the backside of nowhere and it died.

He didn't know about the cooling off trick, so he walked out. Got home about 2 in the morning and called me to complain.

He was really ticked when I told him it would have cranked if he just let it cool.
 
I have been fighting a simliar issue. Start out by replacing the fuel filter (again) and the temp control sensor. Both cheap and easy.
 
Today I replaced the Oil Pressure Switch and the Temperature sensor in the intake. I also purchased the Ignition Control Module.........I'm going to wait until it happens again before I throw the Ignition Control Module in. Those things cost $41 at Autozone and the sensors were $24 for the Oil Pressure Switch and $13 for the Temp Sensor. If it does it again, I'll have the next part to swap....if it doesn't do it again, then I'll return the part and save myself $41!
 
We had this exact issue with an 86 5.0 Mustang my wife owned. It up and died in BFE while we were on vacation. I was ahead in the K5 towing our trailer...didn't notice she wasn't behind me anymore for about 10 minutes.

I turned around and eventually found her on the side of the road...so I turned around again and pulled up behind her. I got out and the car was sitting there idling. she explained it just quit on her, and I lamely pointed out it was running now...when it died again. Seems it'd run for a bit if it sat for a few minutes. We left it, and came back with a car trailer and got it home that way.

I decided I'd try a new fuel filter, and that's exactly what it was. The filter would plug up the longer it ran until eventually there was not enough fuel volume or pressure and it'd die. As soon as it sat for a few minutes the plugged up stuff would settle enough to allow fuel at good enough pressure for it to run again for a while.

I'd definitely try a fuel filter first.

Rene
 
I'll only run AC Delco ignition modules.... seen way too many off brands cr@p out...
 
I have a new fuel filter ready to go now too! :waytogo:

As far as the Ignition Module goes, I paid for their Lifetime Warranty module and didn't get the cheaper one.

This motor has 6000 miles on it after the rebuild........is there a crankshaft position sensor on them that could get hot and shut it down also? I had no codes so I would assume that if it was something major like that it would shoot me a code.........:dunno:
 
No code is what makes me think fuel filter...

CTS or any other sensor would throw a code. My K5 had a code when the CTS was bad, along with a check engine light on.

Rene
 
Code: Meaning:​

12​
No Distributor pulses
13​
Oxygen sensor
14​
Coolant Temp sensor circuit
15​
Coolant Temp sensor circuit
21​
Throttle Position Sensor
22​
Throttle Position Sensor
23​
Manifold Air temperature sensor
24​
VSS (Vehicle Speed sensor)
25​
Manifold Air temperature sensor
32​
EGR system
33​
MAP sensor or MAF sensor depending on engine
34​
MAP sensor or MAF sensor depending on engine
35​
Idle Air Control Valve
36​
MAF Burn-off circuit
41​
No Distributor pulses, cylinder select error
42​
Electronic Spark Timing or Bypass fault
43​
Electronic Spark Control fault
44​
Lean exhaust
45​
Rich exhaust
46​
VATS system fault
51​
PROM fault
52​
CALPAK fault
53​
System over-voltage
54​
Fuel pump circuit
55​
ECM fault
61​
Oxygen sensor fault (degraded sensor)
 
I see no code for oil pressure switch so it could also have been the culprit which is why I changed it.

Tomorrow I will throw the fuel filter in it just because........:D
 
Sheesh this all sounds too familiar... :doah:

After several control modules and various other checks and parts, no codes, i'm replacing the whole engine harness and distributor because everytime i mess with either, it starts working again, but for no determined amount of time.

Mine though would do it cold, hot and apparently after several hundred miles of driving
, as it just left me stranded in St. Louis when i left out of northern Indiana this past Sunday.

When / if it stalls out again, try to determine if you're losing fuel or spark. Thats a good start. Mine is losing fuel pulse signal to the injectors, plenty of pressure and always fires with ether.
 
Man, is hate to make any assumptions unless I know what fuel pressure and volumeis 100% of the time.
Hope its something easy for you
 
My 93 did that for a bit and it turned out to be a cheap cap/rotor that had a bunch of corrosion inside. Had a new ignition module at the time so I did that too, but check the cheap/easy stuff first.
 
well I went ahead and changed out the fuel filter tonight since it only takes 10 minutes! We'll keep driving it now to see if it does it again.

So far I've changed:

Fuel Filter
Fuel Filter Relay
Oil Pressure Switch
Temperature Sending Unit in the Intake
Cap
Rotor
Plugs
Wires
Fuel Pump is a year old!!

I have a new Ignition Control Module on standby if/when this happens again......:dunno:

I never once got any kind of code so it's safe to say that no relays or modules have been the cause........according to my research online so far, if the fuel pump relay was faulty I would get the code 54, and the oil pressure switch is only for cutting out the fuel pump at a loss of oil pressure. After replacing the oil pressure switch I've noticed a more constant reading at the gauge now!:rolleyes:

If the temperature sending went out it would give me a code as well but changing that is easy and cheap so I've done it just because.

If the ignition control module went out it too would cause a code....so I have it for now just in case I need it!:waytogo:

If the oil pressure switch was going bad, it wouldn't cause a code but WILL shut down the fuel pump!! With any electrical switch/relay they can have a short associated with heat and since this ONLY happens after driving for a long time under hot ambient temperatures I think this would be a good place to start, therefore it has been changed. Either way, it's a $24 item that gives me piece of mind!:D

When this first starting happening I couldn't hear the fuel pump cycle when I first turned the key back on to restart it until I let it sit for 5 minutes or more.....this prompted me to change the fuel pump relay. When it started doing it after the fuel pump relay change I noticed that I could hear the fuel pump cycle immediately after it died if I cycled the key on after 10 seconds. Which prompted me to pay attention to the oil pressure when it died. I noticed that the oil pressure was jumping from 30-60psi but would die when registering both 30 AND 60 psi inconsistently but only when it was hot. Since changing the oil pressure switch it hasn't died and I'm getting a constant 60 psi while the engine is running.

I drove it for 45 minutes straight this evening and had no issues at all!!!:dunno:

I'll keep an eye on it now.........I have no way of testing fuel pressure but I'm assuming that if the fuel pump was having an issue it would do what it did before I changed it last year and that was a total loss of fuel pressure but the fuel pump would still run, just not creating enough pressure to run any more than at an idle. I've never heard of the fuel pump creating pressure sometimes and not at others...........:whistle:

The injector pulse comes from the signal from the coil pickup inside of the distributor sent through the ignition control module to the ECM(if I remember right) so any issues here would give me a code. Can someone tell me if I can use a test light to test for injector pulse?

If nothing else, this will all give someone else having a similar problem somewhere to start!:D
 
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