Engine stalls, fuel line problem?

Roger,

Could you provide more insight beyond just "stalling"?

When does the stalling occur? Was it during idling in park/at a stop sign when at very low RPM or was it when you were cruising the highway at 60+MPH? Any problems previously noted during attempted acceleration when at high a rate of speed? (If it was a fuel filter or fuel pump they tend to exhibit signs of failure when delivering the maximum gas flow.) How does the vehicle idle? (A dirty throttle body would cause poor idling and could result in the vehicle stalling at very low RPM.)

Bob

PS How do you rev a "stalled" engine to 3,000RPM?

Hi Bob Thanks for your response, much appreciateed.

The engine stalls at near idle (occurred a traffic light). The engine was warm, running for 30 min. However I noticed some signs of the stall coming before I came to a full stop. The rpm was under 2000. I was traveling at 70Km/hr (45mil/hr), rpm 2000-2400, then braking and gearing down as I approached the stop light. There does not seem to be a problem at high rpm/acceleration. I cleaned the throttle body last summer and have checked it since, it looks good (no deposits).

Roger,

You did not say if the vehicle idles smoothly or not. But if the throttle body is clean and the plugs and wires are also good, then I'd look at the fuel injectors and the air intake servo (AIS) in that order. (I'm assuming from the failure when you were gearing down and then stalling at idle that it probably is not idling smoothly and/or idle RPM is a bit low.)

You could try throwing in a bottle of some good fuel injector cleaner first (I like Chevron Techron) to see if this helps any. If this does nothing, then you might take another look at the throttle body and AIS to make sure EVERYTHING (not just the throttle plate and body where it contacts) is really clean and that the servo is operating properly. I'm not familiar enough with the Saturn AIS to give you any specific instructions on how to test it or if it is a common point of failure, but suspect others in this newsgroup will have more specific experience for you.

Bob

Is this automatic? Does it do this the most at the end of highway exit ramps or right after you've been driving at semi high - high speeds for a few min? If you answered 'yes' to both of these - does the car jerk and shudder right before it stalls? If so, have someone look at the torque converter clutch. It can cause weird stalling, and you'd swear it's an engine problem until you stumble on this.

I solved a stalling problem by removing the EGR valve and cleaning it really well, using a tubular wire brush and solvent. Even though the pintle seemed to move freely up and down, the carbon deposits apparently were sufficient to cause low-RPM stalling.

Pigeon

Thanks Bob, Philip and all aliases for your helpful advice.

The transmission is manual not automatic. It does exhibit almost exactly the symptoms Philip described....

"Is this automatic? Does it do this the most at the end of highway exit ramps or right after you've been driving at semi high - high speeds for a few min? If you answered 'yes' to both of these - does the car jerk and shudder right before it stalls? If so, have someone look at the torque converter clutch. It can cause weird stalling, and you'd swear it's an engine problem until you stumble on this."

.....Bob: Typical idling for my car's engine is around 700 rpm when warm, (1000-1200 when cold). The idling was not smooth when these incidences occurred, and idling was near 700. I will check the throttle body again, and will add fuel injector cleaner, (I have a bottle of STP Concentrated FI cleaner, I never came across the Chevron Techron brand up here in Canada: Canadian Tire or Walmart).

I'll also check the AIS. I will not have a TCC (torque converter clutch) my car has a manual trans. During this last episode, I restarted my car after letting it rest for 9 hours (parked @ work). It began to stall during restart (700-1000 rpm). With the car in neutral I pressed the accelerator up to 3500-3800 rpm. The engine "sputtered" for a bit but then ran without stalling. This action seemed to clear the fuel line. I drove the car in the parking lot to test it, and I noticed that the throttle was high when depressing the clutch to shift gears up to 3rd. ie: the rpm would actually rise above the running rpm (2000) to about 2800-3000 and race while shifting. I recall that this happened before, during an incident when I ran out of gas and restarted the car after re-fueling. As I did then, I turned off the ignition waited for a minute then restarted the engine and it ran fine. Maybe someone can confirm if fuel line problems upsets the computer calibration of the fuel injection system and may require a couple of restarts to re-establish normal operation.

My gas tank was just over 1/8 full, I drove to a gas station and refueled with 91 octane petrol, (normally I use 87 octane). The car has been running fine since. I also visited the Service dept at a local Saturn dealer, although they did not have an available appointment for me to connect the diagnostic computer, the service agent did speak to me as to the possible causes of this problem. Knowing I had a new fuel filter in place, he too suggested the EGR valve and possibly the throttle body and O2 sensor. He also suggested that I may have come across some bad petrol during my last fuel up. That ideally people should refuel when the gas stations receive a new supply of fuel and not get the "cruddy gas near the bottom of their supply tanks". There may also have been some water in my fuel system. What do others feel about this?

I also added a bottle (400ml) of Wynn's MetalOil to the crankcase,and the eng> Date: Tue, 27 Jul 2004 15:04:29 -0500

Remove the throttle body when you do this (get a new gasket first :) It's two torx screws to pull out. You can clean the TB really well after you remove the TPS and IAC valves. And they go on/off real easy, it's obvious how they fit in place. The bolts are 10mm, by the way. Use a 3" extension, 1/4" drive gets in there better than larger ones.

Ok, two things:

• Dissconnect the negative from the battery, let the car sit a few hours, and reconnect it. Make sure both the positive and negatives are tight. Maybe the computer's been having a bad day? I wonder too if voltage problems could cause this?

• Coolant temp sensor, and if your car has it, temp sender. Some Saturns have both - one just works the gauge, the other tells the computer what to do. I knew a kid who had the exact same problem, that was it. Check / replace yours - sometimes even the replacements are bad...

If it's happening when the car's cold, it's NOT the O2 sensor. The O2 sensor is not active when the car is started. IIRC, it's only active once the car's warmed up and a certain time has passed.

If I missed this already being suggested, ignore me. This is a long shot, but you said you've cleaned and messed with the throttle body. Any chance the throttle position sensor is hosed and/or malfunctioning?

My 98SL2 had what sounds like the exact opposite problem you describe - the engine randomly would rev up and then idle around 1800-2200rpms instead of the normal 700-1100. Turned out the TPS was feeding the PCM bad data.

-rj

Philip Nasadowski wrote: