September 21, 2021, 01:10:40 AM

Author Topic: Car bogs down and dies at operating temperature  (Read 410 times)

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Mike001

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Car bogs down and dies at operating temperature
« on: August 18, 2021, 12:00:08 PM »
Hi Hope you can help
I have a 1980 Trans am 4.9, with air. I have had this car since new. I drove it for the first 11 years and stopped driving it in 91 when I had to put a car seat in the back. For the past 30 years I would start it up, run it for a while or take it around the block. It would always start up and run. in the mean time I started to get leaks, oil pan , transmission pan and power steering.
a few months ago I decided to go over the car with a friend who works on old cars. He did a lot of work:

new belts, rad hoses, spark plugs, wires, rebuilt the carb, front end work, new exhaust system, shocks (front and back), rear end oil, thermostat. you get it now!!!

the problem I have is now when I start the car and let it sit for a while the car runs really nice, it reaches operating temperature then just bogs down and dies. I tried to take it around the neighbourhood and once again when the temperature reached normally running temperature it would bog down and start to die off. I would barely make it back home. I would need to start it up every 30 to forty feet to have it coast.

we thought that the carb was getting dirt from the gas tank since the tank was original. I replaced the tank with an new one but I still have the same problem.

Would anyone out there know what would be the problem or a fix

Thanks in advance

Mike

Wheelman

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Re: Car bogs down and dies at operating temperature
« Reply #1 on: August 18, 2021, 02:46:52 PM »
Does it drive OK while warming up? Or do you let it sit until warm, and then drive it?

Is this a Turbo 4.9? The carbs for a 4.9L and a 4.9L Turbo are quite different.
Is the choke releasing completely when warmed up?

What is the "normal operating temp? And is it steady once it reaches it?

Is the vacuum advance working properly?
Are the weights moving freely in the HEI?
Have you tried a new module in the HEI distributor? It could be the thermal paste under the module has dried up.

Could also be the fuel pump, or fuel filter...




« Last Edit: August 18, 2021, 08:00:58 PM by Wheelman »

Mike001

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Re: Car bogs down and dies at operating temperature
« Reply #2 on: August 19, 2021, 09:24:40 PM »

Thank You for the quick response.   
 
 It drives ok while warming up.  I also let it sit there until it warms up and then tries driving away but depends it on the temperature it stalls.

The car is not a turbo. the engine is a 4.9L
Yes the choke releases completely when warmed up?

The normal operating temp is 220. and is steady once it reaches it?

You asked if the vacuum advance is working properly? not sure how to check it?
You asked if the weights are moving freely in the HEI? what is the weights and what is the HEI?

I have ordered a new electronic control module. it should be here next week. I will make sure the thermal paste is placed under the module.

The fuel pump was checked and is pumping good also the fuel filter was changed

Thanks for the quick response.

Wheelman

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Re: Car bogs down and dies at operating temperature
« Reply #3 on: August 19, 2021, 09:55:21 PM »
HEI is the "coil in cap" distributor.
The weights are the first thing you see when removing the cap.
The vacuum advance is the actuator attached to the side of the distributor. You test it with a vacuum hand pump. Same pump that comes with a brake bleeder kit. However I doubt that is your problem.
My guess is either the ignition module is faulty, or the thermal paste is dried up.
It could also be the coil in the cap.
Where are you located?

Mike001

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Re: Car bogs down and dies at operating temperature
« Reply #4 on: August 27, 2021, 05:56:12 PM »
Hi Wheelman

I changed the ignition control module with a new one from rock auto. I placed the white grease on and it did the same. I also changed the coil on top of the distributor.

however when I tried to start the car with the new ICM it would start, after the car temperature went to 220 and died the car would not start with the new ICM. I then installed the old ICM in the distributor cap with the white grease and it started up and then when it reached just around 220 it bogged down and died.  however it would start up again right away but died.

I am really confused that the car ran great for 40 years with some fluid leaking. after I replaced thermostat (twice) rad, hoses, wires, sparkplugs, front end, shocks, exhaust, etc. it just dies????

Not sure what is going on right now.

Wheelman

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Re: Car bogs down and dies at operating temperature
« Reply #5 on: August 28, 2021, 02:47:00 PM »
That is strange.

It is acting exactly like mine when I switched from the stock ignition module to an early model of the MSD6 ignition boxes. When stopped at the lights, heat would build up, and it would shut down until it cooled for a few minutes. I got really fast at switching it back to stock on the side of the road.

Does this car have the ECM (computer under the console) and the carb with wires going to it?

Does it have the 5 pin or 7 pin ignition module.?





Mike001

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Re: Car bogs down and dies at operating temperature
« Reply #6 on: September 01, 2021, 10:58:26 PM »
Hi

The car is a non turbo but does have a ECM compute under the dash. It was suppose to be for the tubos???

The ignition module has 5 pins.

I have changed the ICM from rock auto. it worked when started but died after reaching operating temperature. however it would not start up. I then put the old one back and it started up and stopped . however it would allow the car to start up again. I changed the coil still same problem. sprayed car with carb cleaner at both gaskets. at carb and at spacer. no increase in timing.

Checked fuel lines from new tank to carb to see if touching any heat source. None

I am stumped

any advise

Wheelman

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Re: Car bogs down and dies at operating temperature
« Reply #7 on: September 03, 2021, 04:21:59 PM »
What about the Q-Jet?
Does it have an electrical connection at the front?
I still think something is messing with the ignition.
Maybe a sensor for the ECM.
I have the 1981 Pontiac Service Manual...I'll look up that motor, maybe I will see something.

Mike001

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Re: Car bogs down and dies at operating temperature
« Reply #8 on: September 06, 2021, 10:55:55 PM »
Hi. My car is possessed. now it will not start at all. there is no spark.

please help.

what should I do to trouble shoot this?

Thanks in advance

Wheelman

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Re: Car bogs down and dies at operating temperature
« Reply #9 on: September 07, 2021, 09:42:52 AM »
I have been asking around about your issue...

Consensus is a) bad module ...it is not uncommon to get an aftermarket bad new module
b) distributor pickup coil and/or wires that connect to the ignition module.

I would also check the resistor under the ignition coil, that feeds the rotor.
That is the piece with the copper spring that carries voltage from the ignition coil to the rotor.
May need to slightly stretch the spring to get better contact.
The large rubber washer should have some dielectric grease on it.

Also use an ohm meter to check the rotor...they go bad. wiggle the tab while checking resistance.

If you are close to Royal York and Dundas I can lend you a rotor/cap,
« Last Edit: September 07, 2021, 09:47:16 AM by Wheelman »

Mike001

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Re: Car bogs down and dies at operating temperature
« Reply #10 on: September 13, 2021, 09:36:27 PM »
Hi Wheelman

Thank you for the quick response.

I was wondering is the sketch for a 301 turbo? I do not remember the 4 connector pin sticking out of the distributor.

Also the wire going to the pickup? is this the 8 sprocket steel at the bottom of the distributor.

I have a non 301 turbo with a 5 pin ICM and a ECM which I believe was really meant for a turbo but was installed in some of the non turbos? am I wrong in this assumption?

Thanks

Wheelman

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Re: Car bogs down and dies at operating temperature
« Reply #11 on: September 14, 2021, 01:22:17 PM »
I am wondering if your car is for the US market, and was imported.
The sketch is not for the Canadian turbos. Canadian turbos had the ECM (aka CCC), but not the Electronic Q-Jet.

Yes, the pickup is the 8 prong "thing-a-ma-jig" at the bottom of the distributor.
It is not uncommon to have a flakey connection to the module.

I will see if I can reach a member who had the same car as you. I sold him my 400 a few years ago, so maybe he can help.

His member name is NorthernBandit
http://totas.ca/forum/index.php?action=profile;u=75


« Last Edit: September 14, 2021, 01:26:47 PM by Wheelman »

Mike001

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Re: Car bogs down and dies at operating temperature
« Reply #12 on: September 15, 2021, 06:32:27 PM »
Hi All

Just wanted to let you know that I replaced the ICM (AC Delco, GM) and the car started.

Ran it for an hour in the driveway. temp did go to 220. when I took it around the block it went 215.

I am so happy. now need to tune it up abit as it is running high 1500 to 1300 rpm's

Thanks all for your help

Wheelman

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Re: Car bogs down and dies at operating temperature
« Reply #13 on: September 15, 2021, 08:27:17 PM »
Good to hear !! ;D