Car cranks but doesn't start - Part 2
 

You can find Part 1 to this saga here...
http://986forum.com/forums/boxster-general-discussions/81201-car-cranks-but-doesnt-start.html

A new ACDelco H7 AGM battery was delivered and installed today, replacing the Bosch H8. For the past 5 days, since the replacement of AOS, the car had no trouble starting.
Rather than staying true to, "Don't fix what's not broken", I changed the battery to ACDelco and the car idled rough. I understand this is expected when you disconnect battery so I wasn't worried.

I was careful to watch the charging voltage via this tool I have. It was 14.30ish volts.
Anyway, about 5~10 mins into idling, car died. And I can't start the car anymore.

Why would a car die while idling?
A blocked fuel filter?
Bad plugs? Did the AOS failing contaminated the plugs?

What do you guys think?

Thanks in advance.

I also have Duramatric.
Is there a way to use it to troubleshoot my situation?

Thanks.

Try re-calibrating the E-gas pedal.
Turn key to the on position for 1 minute.
Do not try to start the car. do not touch the gas pedal.
Turn key off for at least 10 seconds.
Then see if the car will start.

changing the battery wont cause it to run rough.

Need more info. car wont start isn't enough.

does it crank over?
does the tach move?
did you check for codes? If so are there any?

I wouldnt rely on the tool telling you charging volt, I would check the battery with volt meter while the car is running. 10 minutes isn't enough to drain the battery down so there is still something else going on with the car besides the battery.

think I know what the issue is, but want to see answers to the above first. I'll have some steps for you to perform depending on answer. I dont think your battery has anything to with this issue or the one in your other post. Doesn't seem sound like your intermittent no start was resolved from then.

Hi blue62,

Does this, "Turn key to the on position for 1 minute" means to turn it turn so that you get the oil level reading? I did that. And then tried to start the car for 10+ seconds. Nothing.

BTW, I am going to take the new battery out and replace it with what I had yesterday.
This battery gave me no trouble until yesterday. It is currently being charged.

Hi Stl-986,

It cranks. It always did.
The tach does not move.
I have a generic code reader and nothing shows there. I am wondering if Durametric will show more. (But then, I don't know what I am looking for in it... :() )

Yes, I agree!

First, do a search for CPS/crank position troubleshooting. If that testing is successful, do the following. Since your tach doesn't move at all, this is most likely the issue, but I would do the below as it takes less then a half hour to do also.

, do the following
put top in service position
remove engine cover carpet & engine cover
DO THE NEXT WITH ENGINE COLD!!!!

Remove fuel cap
Wait 1 minute, then put back on

Go to pass side of engine. Using a small screwdriver, press the schrader valve on the fuel line. Does fuel come out? Valve may have a cover on it, if so, remove.

If no fuel, turn key to ON position
Do above again, any fuel come out?

If no, remove fuel pump relay (gray with pink wriring)
make a jumper wire
Jumper fuel pump
turn key to on, dont start car
Go press schrader valve at fuel rail.
Any fuel come out?

If the last answer is No, then you need a new fuel pump.

Some would say to jumper the fuel rail, turn key to on and listen for pump (it's under the battery). But depending on how much gas is in the tank you might not hear it run. I know I didn't with 3/4 full tank 2 weeks ago.

Wow... I need to research where the "schrader valve on the fuel line" is. Perhaps I will upload a picture of my engine bay and you can circle it for me. :)

Thank you Stl-986.

P. S. So.... you don't think it is dirty plugs, right? I was SO hoping it would be 11 year old plus plugs...

The valve is on the front (forward) end of the bank 1 (passenger side) fuel rail.

Be careful while doing this, the test is to see if the fuel pump is pressurizing the fuel rails. If it does, then you will have fuel spray out and into your engine bay (this is why he told you to do it with a cold engine).

Have a fire extinguisher ready.

Sent from my SM-G970U1 using Tapatalk

no, dirty plugs are not going to cause this. They can't cause the car isn't even running.

"Have a fire extinguisher ready. "

OMG!!!
I don't even have one for my house! (I did think about buying one for the car. I am not crazy, right? That's normal Boxster love, right? ;) )

Thanks ike84!

OK, here is the update. The car starts!

While researching the "CPS/crank position troubleshooting"... I came across this gentleman, Brian Minson. https://youtu.be/ZSmehtE8Ctk

At 14:00 mark, he explains how to check the CPS.
It is just what YOU asked me earlier, "does the tach move?" I say no, but the amount of 'movement' is way smaller than I was expecting. I will look for this tiny tach movement, or not, the next time when the car won't start. In fact, it was to confirm this tiny tach movement when the car magically started. Brian's description of CPS failed car is 95% dead on with my experience.

Questions:
- is failing CPS sensitive to temperature? Ambient temperature? Or, engine temperature?
- Could a bad CPS stop the engine while driving?

As always, thank you for your help. :)

heat can cause the cps to have issues
no it wont stop the engine from running

The fact that your tach moves means that the issue isn't the cps

You have a failing fuel pump. everything you describe is exactly what happens when it starts to fail. I know, just went through this 2 weeks ago. Sometimes it will work, some times it wont.

So that everyone doesn't have to ask every time, put your car info in your signature. 99 & earlier use 1 type of pump, 2000 & above use a different one. Replace it before it strands you somewhere. You haven't said if you checked for codes at any time and if any where shown. If you did before it started and there were no codes....then it is fuel pump.

If your tach moves....it isn't CPS

You should always have an extinguisher in the house and one in the car....regardless of what kind of car you have. Hell, I have 3 in the garage and 2 in the house. Better to have and not need then need and not have. Cheaper too.

I am not sure if tach moved when my car wouldn’t start. Yes, if the tach jumps a bit without car starting, I now know that I can eliminate CPS. I just don’t have this data point, yet.

If the problem is the failing fuel pump, shouldn't I have had some symptoms while I was driving?

I have been checking for the codes with Durametric and generic code reader since the car-start-problem first showed up a month ago. No codes. Not then. Not now.

You are right. And I should know better as I was a member of Fire Team at my last employer. :)

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