Tough Day No Start - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Jgkram · 02-11-2018, 01:57 PM

Ok, read a lot of posts and tried to sort through this myself now need a little help please.

Replaced brake switch to pass inspection. Started car briefly just to check lights. Turned off but smelled strong gas oder, thought nothing of it. Went to start next morning and crank but no start. Hmmm...started reading the forum.

Tested fuel pump operation by jumpering pins 30 & 87 on fuel pump relay. Could hear the pump running while I was in the footwell and through the filler neck. Next, pulled a coil pack, stuffed a plug in it and tested for spark. Got a nice blue spark. Thought, well isn't this nice. Tried to start again. Got crank but no start. Instruments tick slightly when key is turned (like normal) but when cranking I get no movement on the tach needle. It stays dead still. No CEL thrown.

Lastly put a multimeter on the CPS but I think I had my leads wrong. However I got no reading. I would discount this part for now as I need to repeat the sensor check and make sure my leads were set up correctly.

Thoughts before I send this off to the mechanic? I really want to win this one myself so all help appreciated.

kk2002s · 02-12-2018, 11:42 AM

From what I understand, no RPM during crank points to CPS. Jumping Fuel pump relay and hearing fuel pump only helps to eliminate fuel pump. You could try and start with jumper to narrow down to Relay (If starts with jumper, no start with relay)
BUT no RPMs -> CPS typically

Jgkram · 02-12-2018, 11:59 AM

Thanks for the feedback guys. Here's a little more information that I've received. I talked to a technician at one of our local Porsche independent shops (friend of a co-employee) and he told me that if I got spark (which I did) then it could not be the CPS. He also mentioned that a good fuel pump doesn't mean fuel pressure so that is still in question. Lastly, he said I need to scan the car to pull any pending codes which I will do tonight.

Thanks again for all of your help and I will keep you informed in case my journey helps someone else.

Jgkram · 02-18-2018, 04:15 PM

Thought I'd post an ending. May help some others. Working through my crank, no start issue I did the following:
1. Checked for spark by pulling the #6 coil pack, inserting a spare plug and testing. Nice blue spark so no problem here.
2. Pulled full pump relay and jumpered the pins. Listened for pump running. Check, no problem here.
3. Tested fuel pump relay by applying 12v and listened for "click". Tested load side for continuity. Check this off the list.
4. No fuses blown.
Still no start.
5. Borrowed fuel pressure gage fro autozone. Pulled test port cap off and installed the gage hose. Car started right up. What???

Fuel pressure was only 48 psi. Should be reading around 55 psi. Called an Indy friend he said could be a fuel pump going south or more likely a stuck fuel pressure regulator. Next time I'll tap on the regulator earlier in the process. Anyway she's running!

Lapister · 02-19-2018, 11:02 AM

48 psi does sound low if you are supposed have 55. Did you leave the FP tester on after shutting down to see how long it holds pressure? If it goes to 0 after key off you likely have a bad check valve integrated into the FP. Check Filter? Also if later than 02 model year the filter is part of the FP.

Jgkram · 02-19-2018, 02:16 PM

Thanks Lapister. I did notice that the gage dropped more rapidly than I would have anticipated. I thought it would hold pressure once the ignition was turned off but that was not the case. Mine is an '01 so I have a separate filter that was just replaced about 1 year ago.

Looks like to be safe I need to be on the hunt for a cheap full pump. Oh, I forgot to mention that I tested the CPS while I was at it and got a reading of .895 ohms so I checked it off of the list as well. Still stumped as to what could have happened but been driving it for the past two days (it's my daily) with absolutely no issues.

Strange....