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car stalls 0n 85


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I can't seem to figure out why? THe car starts fine,it runs fine ,it idles fine and every now and then when i am stopped at a light it stalls out and then it

starts right up .It has the 5.0 v-8 with the 4 barrel and I checked all the hoses for leaks and I checked the fuel filter.Any ideas?

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This sounds like an ignition system problem. Is there any rough running just before the stall? What about after the restart?

To eliminate the 'low voltage - 12V' side of the system, rig up a small 12V lamp & socket with long wires. In the engine compartment, ground one wire. Connect the other to the pink wire which feeds the HEI distributor. This pink wire receives 12V when the ignition switch is in the 'RUN' or 'START' positions.

Route the lamp past the rear of the hood so that you can see it at all times. You may wish to fashion a tube so the lamp is visible in bright sunlight. If, at the moment the engine stalls the light goes out, you have electrical problem on the 'primary' (low voltage) side of the ignition system. This could be due to worn contacts in the ignition switch. If it doesn't go out, the problem may in in the 'secondary' (high voltage) side.

The high voltage side is harder to troubleshoot since your problem corrects itself with a restart. Fortunately, the GM HEI distributor is simple and has only three electrical parts: ignition coil (in the cap), module and pick-up coil. Before you do anything, check the little 3 wire harness which runs from the base of the distributor to the connector on the side of the cap. The insulation may be falling off & an intermittent short may be occurring. Rather than replacing one or more of the three electrical parts, you many wish to drop in a bone yard HEI distributor from an '81 to '90 GM V8. CCC (Computer Command Control) was used during those years and the spark timing was controlled by the ECM. An earlier HEI distributor will not work with CCC.

I had a somewhat similiar problem which turned out to be the HEI pick-up coil.

My car wouldn't stall but would sometimes not start when warmed up. It took me several months to isolate the problem.

Keep us posted,

Paul

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There isn't really any rough idling before the stall,it just idles down to a stall like its running out of gas.Then it starts immediately but doesnt hold the idle untill i get going again,I have to give a liitle on the throttle before putting into gear and then its fine for a while untill it happens again.Sorry about the wait I was away.

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I had the same problem. Needed to replace the torque converter clutch solenoid within the transmission.

When the torque converter clutch malfunctions it stays stuck on a higher gear.

This can cause a stalling and bucking condition when the vehicle is slowing down for a stoplight.

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I've experienced the TTC solenoid problem on a couple of cars. When this happened to me, the problem would go away when I shifted into neutral. Everything worked as it should upshifting through the gears from a standing start. Once the torque converter locked it was as if I werre driving a manual transmission car in high gear and tried to come to a stop without using the clutch.

Replacing the TCC solenoid requires only removal of the pan, you don't need to R&R the transmission. At the time, it cost me about $135 for the fix. That was five years ago; don't know what it might cost now.

Ed

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1onesy:

Can you clarify: Does the stalling occur after the car has come to a stop & has remained stopped (in gear) for more than a few seconds? If so, then the TCC (torque converter clutch) solenoid is NOT the problem. If the TCC was hanging up, the engine would stall as soon as you stopped. As was mentioned, it might also buck while slowing to a stop.

Based upon you comment: "I have to give a little on the throttle before putting into gear" suggests that the problem is NOT ignition but fuel (carburetor) related. Earlier this year, you were having trouble with this Rochester carburetor. Was it rebuilt? It sounds as though it needs a complete going over (rebuild) with the proper adjustments made both during the rebuild & after it's back on the car.

The Rochester E4MC & the CCC system is very reliable and provides good drivability & fuel economy. Compared to electronic fuel injection systems, it's rather simple. Get it squared away and it will work quite well.

Paul

PS: I had a rough idle & some 'takeoff' issues until I followed the shop manual and properly adjusted the carb after my last rebuild. Once I got it setup, those problems went away. The emissions are very low & the idle is now amazingly smooth.

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I unplugged the wire harness to the tranny for the torque converter about 15 years ago so I think that its got to be something with the carb or emission stuff.The carb was replaced about 10 years ago. I have no clue on how to adjust the carb and trying to find someone that does these days is very hard.

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Your not kidding-- finding someone to work on these carbs. I'd pay someone to show me how to rebuild one.

I still say you might have an emissions related issue. When is the last time the EGR valve or PCV valve has been changed? Maybe the carb needs to be tightened down. There is a whole list of things that are serviceable every 30k or X amount of months. If any of those are not working right it can stall your car too.

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1onesy

I'm going to go back to the original post. The subject is "Car stalls On 85" I haven't seen yet where the number '85 comes into any of the threads.

Are you by any chance trying to run this car on E85 fuel?

Ed

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1onesy has a 1985 Riviera with the venerable Olds 5.0L engine.

E85...! I hope not. I'd slid my wrists first...

Seriously: if the carb is suspect & money is available, it might be wise to just buy a rebuilt unit from a place such as: Performance Quadra-Jet Carburetors, Custom Restorations

You are looking for: C) 4 Barrel Rochester E4MC (with electric choke upgrade)

Once the carb is installed, the 'trim' adjustment for the idle mixture requires just an old fashioned analog dwell meter. The procedure is very easy & allows you to see the ECM (electronic control module) in action. Failure to make this final trim adjustment may cause rough idle, stumble upon takeoff and high idle emissions...

Paul

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Because he never came right out and said it, (nor did anyone else) I was taking a WAG.

Don't slit your wrists yet,.

I was reading some articles about converting/modifying your carb to work on E85. 85% alcohol and 15% highly volatile gasoline gives you a fuel with an octane rating around 105. (Alcohol dragsters have their own class.) You don't get near the mileage, but it doesn't cost you near as much per gallon either. What I summarized from what I read is that E85 is a really cheap high octane fuel - much cheaper than Av-gas or racing fuel - that can help your engine produce more power if you're willing to make some changes. Probably not worth it for day in day out driving, but it might be worth considering for all out racing.

Ed

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I would agree with doing something with the carb now and would put a new fuel pump on. I just went through a whole mess of related problems including the stalling at lights during 1/2 hr. warm up. I found the timing (that the so called expert for these cars was supose to set) was off 20degrees. I know you might be saying how could it run but it did and not too badley so I thought . It even threw all the shift points way off that caused all the trouble in earlier posts. I'm so good at setting the mixture control now and can do it blind folded.

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I don't know what e85 fuel is but I'm not using it ,its got the olds 5.0.I will check the egr and pvc and its funny that the fuel pump was mentioned because i had a problem years ago,when i would put the car in gear it would stall out.Every moron I took it to would dive right into the carb and not find the problem untill oneday I noticed a leak from the pump and when I replaced it the problem was solved.Can it be that the fuel pump can fail intermittently?There is no sign of a leak from the pump.

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Does it make any difference how full your tank is? A weak pump can't pull from an almost empty tank. When the tank is full, the pressure from the weight of the fuel at the top of the tank can push fuel to the pump. If the tank is almost empty and the fuel has no weight, the pump can't pull the vacuum necessary.

Ed

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You could try replacing one bank of spark plugs to see if it helps the burn enough to keep it from stalling.There could be many things contributing to the stall and I know they could be costly to replace them all especially the carb. I had a carb specialest here rebuild my carb and it works very well but I was sceptical of his work at first untill I found the real problem elsewhere later on.

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Because 1onesy states that "THe car starts fine,it runs fine ,it idles fine", I don't think the stalling issue is ignition related. If the plugs were worn or the spark insufficient to properly ignite the mixture, he would be experiencing other issues. Starting would be dicey, the idle would be rough and acceleration would be poor (misfiring would occur).

There is a simple test which will rule out (or rule in!) the fuel pump.

1) After the engine has been running, shut it off & remove the air cleaner lid. There is no need to remove the entire air cleaner housing.

2) Take a wooden popsicle stick and carefully drop into the slot right in front of the lid's threaded shaft (see the attached image). The stick will come to rest on top of the float pontoon. Gently press it down a bit & release to feel the pontoon floating in the fuel.

3) Scribe a line on the stick at the top of the slot.

4) Take out the stick and keep it in the car.

5) Replace the air cleaner lid.

6) When the next stalling situation occurs, DON'T restart the car.

7) If you're out of traffic, remove the air cleaner lid and carefully drop the stick back in.

8) If the line is visible, then the float bowl is filled to the same level as before.

The fuel pump was doing it's job & the engine didn't stall due to lack of fuel.

I don't think the fuel pump is bad. If it's output was low, you might also experience surging or bucking while accelerating or cruising (due to low fuel level in the float bowl).

As was stated, the EGR system could be malfunctioning. The EGR valve might be OK but the solenoid which modulates the vacuum to the valve's diaphragm (via the ECM's signal) might be bad. To rule out the EGR system, you'll need to remove the valve, make a temporary gasket to block off the exhaust gas and reinstall the valve. The engine will most likely ping under acceleration without EGR (the combustion temperatures will be higher). If it still stalls, you have ruled out the EGR system.

Put on your Sherlock Holmes hat. Troubleshooting is a process of elimination rather than a process of just replacing parts (this gets expensive!). I have worn this hat many, many times in the 27 years I've driven my '84 Toronado.

Paul

Edited by pfloro (see edit history)
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