Starting Problem---again

[Gems]

Originally Posted by bnaylor

Did you have crank position sensor problems in the past?

Not that I'm aware of....

Can the crank or cam position sensors be intermittent? (Like 98% of the time OK and 2% of the time flakey)

[BNaylor]

Originally Posted by Gems

Not that I'm aware of....

Can the crank or cam position sensors be intermittent? (Like 98% of the time OK and 2% of the time flakey)

I'm not saying it is your problem but it is just one item that can cause a similar problem. Those Hall Effects sensors are heat sensitive. Symptoms are hard starting or stalling when driving down the road. And yes they can be intermittent along with no SES/CEL light or any odb-ii codes.

It always the basics, either ignition or fuel.

One other item, the MAF sensor.

[Gems]

OK... I'm going away on a business trip for the next 4 days... The Impala will be under the custody and care of my wife ... If there is a intermittant problem she will be sure to find it!

[phewop118]

The crankshaft position sensor can cause intermittent starting problems, but it'd also cause intermittent stalling. The fuel pressure regulator can cause intermittent starting problems if it's going bad. Usually, it will be if you start the car once it is warmed up. It will crank, start for a second, but not get up to idle rpm, then fail. You might get this once in a month's time.

[Gems]

Originally Posted by phewop118

The crankshaft position sensor can cause intermittent starting problems, but it'd also cause intermittent stalling. The fuel pressure regulator can cause intermittent starting problems if it's going bad. Usually, it will be if you start the car once it is warmed up. It will crank, start for a second, but not get up to idle rpm, then fail. You might get this once in a month's time.

OK... I've been away on business all this week (I still am)... My wife just called me and it happened again... She was running local errands, starting and shutting the car a few times inbetween local stores... Finally, at the post office, she had starting problems... It would start, stumble and die... She tried a few times with no luck... Then waited a few minutes and it started right up and ran fine... It has never stalled after running... You are one of several who have mentioned the FPR, but "bnaylor" has said in this thread it is rarely the cause of this problem... Any comments??... I'll be back to my home tomorrow as long as I get thru the airport security with a carry-on bag full of electronics!!

[BNaylor]

Based on my experiences the FPR is very seldom the problem but there may be exceptions. However, proper troubleshooting is required. I had recommended running a fuel pressure test so you could make a determination. The fuel pressure check tests the FPR and as to whether it is functioning properly. Based on the reading with vacuum connected and disconnected at the FPR, if the reading on the gauge deviates by 7 psi or more than the FPR should be replaced. Based on your symptoms you could have a problem any place in the fuel circuits. It could be the fuel pump or the fuel pump relay. An ignition related problem can cause it. A bad MAF sensor gives similar symptoms.

[Gems]

OK... When I'm home this weekend I'll probably buy the fuel pressure gage and take some readings... I'll keep you all posted and thanks for the continued help and support!!

[Gems]

OK, I'm back again with this problem...

First of all, I must say to 'bnaylor', that I'm an idiot... Instead of exactly taking your prior advice I bought a new fuel pressure regulator last weekend and installed it... Several guys on the "naioa" forum told me they had the exact same problem and it was a bad FPR... So I replaced it last saturday and the car has been good until tonight...

Once again my wife was running local errands, with the A/C running, and after a few starts and stops between stores the car again would not restart... It would fire, and die in about 1 second... She then let the car sit for 5-10 minutes and it restarted and ran perfectly... During the restarts she had the A/C off... I just restarted the car in the driveway a few times and it seems fine...

So consider me STUPID and give me some advice again as to where I should start to troubleshoot this intermittent problem...

Thanks in advance...

[BNaylor]

Sorry to hear the problem is still there.

What problem one Impala owner has may not be applicable to the other so it is really hard to say. The problem with intermittent problems such as yours items like the FPR winds up getting replaced in the course of troubleshooting. At least you can rule it out. Also, it doesn't help when no DTC error codes are triggered with a SES/CEL light.

Back to the basics. It is either fuel or ignition. Based on my experience with the SII 3800 engine which is over 8 years and various GM makes I would say taking an educated guess that for fuel - possible fuel pump. For ignition - the crank position sensor. But based on your symptoms I would put emphasis on fuel first.

[Gems]

Thanks 'bnaylor'... In one of your prior responses you did mention the fuel pump relay as a possibility... Where is that relay located and is there a test (voltage or current or resistance) that I can do on it?...

Also, I did clean the MAF sensor a couple of months ago with electrical contact cleaner... Of course, that wouldn't fix a flaky MAF sensor, it would just make it a clean and flaky MAF sensor...

[Gems]

By the way... When I replaced the FPR I pressed on the schrader valve to release the fuel pressure... Very little gas dribbled out, only about a teaspoon, or less... Is that normal?... I thought I'd get more gas under some pressure to come out... The car had been off for about 2 hours prior to me pressing on the valve...

[BNaylor]

Originally Posted by Gems

Thanks 'bnaylor'... In one of your prior responses you did mention the fuel pump relay as a possibility... Where is that relay located and is there a test (voltage or current or resistance) that I can do on it?...

The fuel pump relay should be located in the engine compartment fuse box. On the back of the lid is a diagram of all fuses and relays located there. With ignition to on there is always 12 volts DC on one side the the relay coil. The PCM module provides a low/ground to energize the relay. The output from the relay to input of the fuel pump will be around 12 volts.

Originally Posted by gems

Also, I did clean the MAF sensor a couple of months ago with electrical contact cleaner... Of course, that wouldn't fix a flaky MAF sensor, it would just make it a clean and flaky MAF sensor...

Yeah, thats true. On the MAF sensor you could try this test. Just remove the electrical connector to it. All you will get is an erratic idle until the engine warms up. You will have normal driveability. I've driven with a MAF sensor disconnected for a week until my part arrived. The PCM will detect the MAF sensor signal missing and use pre-programmed MAF/VAF tables along with a few other sensors. Your problem doesn't sound like a flaky MAF but it won't hurt to rule it out.

Originally Posted by Gems

By the way... When I replaced the FPR I pressed on the schrader valve to release the fuel pressure... Very little gas dribbled out, only about a teaspoon, or less... Is that normal?... I thought I'd get more gas under some pressure to come out... The car had been off for about 2 hours prior to me pressing on the valve...

After about 2 hours or more that sounds normal. What counts is when the fuel pump primes for the two seconds at ignition on where pressure will be back up, hopefully in spec. Only way to tell is to connect the fuel pressure gauge.

Hope the info helps.

[Gems]

"Just in case", I called my local Chevy dealer to see if he had the fuel pump relays in stock, and what they cost... He tells me they have them in stock but there are two types... One cost $12 and one cost $30... He didn't know the difference, or why, but it depended on what code number was marked on top of the relay... Does that make any sense??

(The relay in my car is marked with two numbers: 7866 and 12077866... It is BLACK in color...)

[BNaylor]

I would go with the advice from the dealer. Part number 12077866 is correct and the GM list price is around $29.98.

[Gems]

Well I'm thinking for 30 bucks I should just buy that relay and put it in...

BTW, I just received my ACTRON code reader today... I plugged it into the ODB port, turned the ignition to "ON" and it scanned and came up with zero codes... No surprise since the SES/CEL light has never come on (why don't they call it an OBD light??)...