No start after storage / after pulled fuel pump fuse - 986 Forum

jaykay · 08-05-2016, 08:01 AM

She turns over but will not start. Probably due to my intervention.

After storage, I turn over the engine on the starter to move oil throughout the engine prior to actually running it

After jogging the engine with the starter I pulled the fuse so that she wouldn't start...there was cough so I made sure she didn't run.

Now with fuse in it won't start at all. I have cranked as much I can on one battery charge and motor duty cycle. Each time I believe I can hear the pump running with ignition on.

Any thoughts?

911monty · 08-05-2016, 10:12 AM

Quote:

Originally Posted by jaykay

She turns over but will not start. Probably due to my intervention.

After storage, I turn over the engine on the starter to move oil throughout the engine prior to actually running it

After jogging the engine with the starter I pulled the fuse so that she wouldn't start...there was cough so I made sure she didn't run.

Now with fuse in it won't start at all. I have cranked as much I can on one battery charge and motor duty cycle. Each time I believe I can hear the pump running with ignition on.

Any thoughts?

Maybe time to pull the IT trick. Disconnect the battery and boot the computer?

jaykay · 08-05-2016, 11:38 AM

Yes thought of that.....cycled the batt switch. And now pulled battery out completely for 24....had to recharge it anyway after the cranking attempts

Perhaps I need to connect the battery terminals together to get a reset

911monty · 08-05-2016, 11:51 AM

Well after 24 hrs any settings stored in memory should be gone and computer should be back to base settings. I think it is recommended to disconnect battery for 20 min to wipe out stored memory. Good Luck!

jaykay · 08-05-2016, 12:29 PM

I hope there is something that will reset otherwise........relay, pump, crank sensor etc??

It is not in a convenient place to work on and has to moved fairly quickly

911monty · 08-05-2016, 01:05 PM

Sux about the work space. So simple preliminary tests would be to hook up a fuel pressure gauge to confirm pump running and fuel pressure, if no rpm indication upon cranking then CPS could be suspect. Gotta ask if you checked fuse to immobilizer?

It's probably the fuel pump....

jaykay · 08-05-2016, 02:35 PM

Quote:

Originally Posted by 911monty

Sux about the work space. So simple preliminary tests would be to hook up a fuel pressure gauge to confirm pump running and fuel pressure, if no rpm indication upon cranking then CPS could be suspect. Gotta ask if you checked fuse to immobilizer?

It's probably the fuel pump....

I believe I hear pump hum and stop in the start sequence with ignition on.

I didn't check the immobilizer fuse....will do...and I had not thought to do this thanks! I even have an external one that I can get to without opening the box (water proof case)

C4 is the fuse location and I have replaced the pump fuse in the right spot its 30 rather 25 as listed on the map

The tach flickers at bit at its 0 rest spot so......that should mean good Cps unless it should be doing more at starte speed.

Is there a convenient place to measure fuel pressure?

911monty · 08-05-2016, 02:48 PM

Jaykay; That's about all the CPS will do at starter speed. Attached is a diagram of the fuel system. Item #6 is the fuel pressure test port on the fuel rail. Remove the cap and there is a schrader valve underneath. Either have someone watch the gauge when you turn the ignition on or make sure your gauge has the pressure bleed button so pressure is trapped.

http://www.********************************************.com/porsche-parts/hardparts.php?dir=986-97-04&section=107-05

edit: Conflicting info on that immobilizer fuse, some say engines won't crank if blown. I don't know haven't tested myself, but figure worth checking.

jaykay · 08-05-2016, 02:59 PM

Thanks that sounds like a test I can manage in my environment......hopefully that test port is really schrader compatible!! Someone in the GTA have the Porsche tester?

Might as well change out the regulator after....I am sure there must be an ignition only pressure spec for fuel pressure

911monty · 08-05-2016, 03:09 PM

Quote:

Originally Posted by jaykay

Thanks that sounds like a test I can manage in my environment......hopefully that test port is really schrader compatible!! Someone in the GTA have the Porsche tester?

Might as well change out the regulator after....I am sure there must be an ignition only pressure spec for fuel pressure

Fuel pressure should be 3.8 bar or ~50-55psi. Don't know if you have an AutoZone or O'reilly Auto close by but they have a FP gauge they will loan out.

jaykay · 08-06-2016, 10:56 AM

Thanks man .....is a 90 deg fitting needed?

911monty · 08-08-2016, 08:46 AM

Quote:

Originally Posted by jaykay

Thanks man .....is a 90 deg fitting needed?

Hey Jaykay did you get this sorted? I was out for the weekend. I hope everything started ok.

No a 90 deg fitting is not needed. I'm sure you know but the pressure tap is on the fuel rail passenger side, outboard of the intake manifold between cyls #1& 2. It is the cap just below the engine compartment temp sensor.

jaykay · 08-08-2016, 10:24 AM

Hey man thanks for your help....yes got it sorted for now. It seems that there must be something intermittent in the fuel pressurization system.

I pulled the battery for 24 hrs, changed fuses/switched existing ones, made sure I went through three pump pressurization cycles on the pump before ever starting. 2nd crank it lit up! It starts every time now. Prior to this multiple attempts failed

I will still have to go through some diagnostics to find out where the problem is.....ethanol clogging my regulator??

Fuse connections?

J

911monty · 08-08-2016, 10:40 AM

Cool! Did you put a gauge on it and see any problem? I guess you guys have ethanol up there also, doubt that is causing issues..... But maybe some varnish stuck the regulator open while cranking (high vac) So might be worth running some Tehran through it. Anyway glad it worked out.

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