Go Back   986 Forum - for Porsche Boxster & Cayman Owners > Porsche Boxster & Cayman Forums > Boxster General Discussions

Reply
 
LinkBack Thread Tools Display Modes
Old 01-17-2014, 11:17 AM   #1
Registered User
 
CrashTest's Avatar
 
Join Date: Nov 2013
Location: Wisconsin
Posts: 35
fuel pump diagnosis: stalling when warm

I'm having some weird issues with my 98 2.5 and think it might be the fuel pump. Before I drop a few hundred and get all stinky swapping the pump - is there any way to test the pump?

I was driving today - normal commuting and had no issues. Parked, returned, drove, everything fine. Then later in the day I hit some nice back roads, high RPM, high load stuff. When I pulled up to a stop sign the idle began bouncing up and down, almost stalling. Not sputtering or running rough, just up and down. At the next stop sign, the idle would dip and it would stall. It would immediately restart with the key, and if I feathered the throttle it would be fine. If I put it in neutral and left the throttle alone it died.

I read some accounts of bad pumps causing stalling when hot. It's odd that at high RPM high throttle opening, even in bend, I had no hesitation or stumbling but at rest, idle it would die. If the pump is going, wouldn't it have trouble with high-demand situations?

I pulled the relay and popped the cover off. No broken connections apparent, looks fine. The car sat maybe 10min and is behaving better. Idle a little wavy after throttle blips in neutral but no stalling.

Ideas?

CrashTest is offline   Reply With Quote
Old 01-17-2014, 11:37 AM   #2
98 Arctic silver 986
 
tommy583's Avatar
 
Join Date: Jul 2011
Location: Upstate, NY
Posts: 1,313
Garage
I had the same problem last summer. I cleaned the throttle body and the idle control valve. Ran great after that. Cost was one afternoon and a can of carb cleaner.
tommy583 is offline   Reply With Quote
Old 01-17-2014, 01:37 PM   #3
Registered User
 
woodsman's Avatar
 
Join Date: Feb 2013
Location: Land of naught
Posts: 1,302
when mine went it displayed a UNwillingness to rev high and was down on power. It also stumbled when at low revs. The next day it wouldn't start. I wonder if you've got a bad tank of fuel? Checking the fuel pressure is easy if you've got a $50 pressure tester (schrader valve- same as most cars).
__________________
Death is certain, life is not.
woodsman is offline   Reply With Quote
Old 01-17-2014, 02:05 PM   #4
Registered User
 
heliguy's Avatar
 
Join Date: Nov 2008
Location: Florida
Posts: 1,111
Quote:
Originally Posted by woodsman View Post
when mine went it displayed a UNwillingness to rev high and was down on power. It also stumbled when at low revs. The next day it wouldn't start. Checking the fuel pressure is easy if you've got a $50 pressure tester (schrader valve- same as most cars).
Same symptoms when mine went.
heliguy is offline   Reply With Quote
Old 01-17-2014, 07:42 PM   #5
Custom User Title Here
 
particlewave's Avatar
 
Join Date: Mar 2012
Location: WA
Posts: 6,087
Garage
Quote:
Originally Posted by tommy583 View Post
I had the same problem last summer. I cleaned the throttle body and the idle control valve. Ran great after that. Cost was one afternoon and a can of carb cleaner.
This is a good place to start and most likely needs to be done anyway. Doesn't sound like fuel pump.
particlewave is offline   Reply With Quote
Old 01-18-2014, 07:03 AM   #6
Registered User
 
CrashTest's Avatar
 
Join Date: Nov 2013
Location: Wisconsin
Posts: 35
Thanks all - will clean the TB and ICV today and see what happens.
CrashTest is offline   Reply With Quote
Old 01-18-2014, 07:25 AM   #7
Registered User
 
Join Date: May 2011
Location: Miami florida
Posts: 1,591
Could also be a vacuum leak. If you have a scanner, check the MAF and fuel trim values. If the Maf value is lowand the fuel trims are positive and high, then its likely a vacuum leak.
__________________
Current car

2000 Boxster 2.7l red/black

Previous cars

1973 Opel Manta
1969(?) Fiat 850 Convertible
1979 Lancia Beta Coupe
1981 Alfa Romeo GTV 6
1985 Alfa Romeo Graduate
1985 Porsche 944
1989 Porsche 944
1981 Triumph TR7
1989 (?) Alfa Romeo Milano
1993 Saab 9000
san rensho is offline   Reply With Quote
Old 01-18-2014, 11:14 AM   #8
Registered User
 
CrashTest's Avatar
 
Join Date: Nov 2013
Location: Wisconsin
Posts: 35
Took the ICV off to clean it - two things. Clearly the throttle body has never been cleaned. And the plastic body of the idle control valve is cracked. Going to replace the valve and gasket and see what happens next.

Hey san rensho - happen to have a 3Rensho?

Here's my restored 86:

CrashTest is offline   Reply With Quote
Old 01-18-2014, 11:25 AM   #9
Registered User
 
CrashTest's Avatar
 
Join Date: Nov 2013
Location: Wisconsin
Posts: 35
edit: $270 for a replacement - silly.

Turns out the door, or valve, inside was stuck. It's freed up now - going to soak it and clean it a little more before shelling out $300 for a new part. Yikes.
CrashTest is offline   Reply With Quote
Old 01-18-2014, 02:23 PM   #10
Registered User
 
woodsman's Avatar
 
Join Date: Feb 2013
Location: Land of naught
Posts: 1,302
thanks for the update and may I say- I love that bike, including the colour!
__________________
Death is certain, life is not.
woodsman is offline   Reply With Quote
Old 01-18-2014, 03:02 PM   #11
Registered User
 
Join Date: May 2011
Location: Miami florida
Posts: 1,591
Quote:
Originally Posted by CrashTest View Post
Took the ICV off to clean it - two things. Clearly the throttle body has never been cleaned. And the plastic body of the idle control valve is cracked. Going to replace the valve and gasket and see what happens next.

Hey san rensho - happen to have a 3Rensho?

Here's my restored 86:


Yes I do! I got one of the first to come from Japan, but its a restoration project at this point. I need to find an old campy group to bring it back to its former glory.

Yours looks great. Nice conversion. SS or fixed.
__________________
Current car

2000 Boxster 2.7l red/black

Previous cars

1973 Opel Manta
1969(?) Fiat 850 Convertible
1979 Lancia Beta Coupe
1981 Alfa Romeo GTV 6
1985 Alfa Romeo Graduate
1985 Porsche 944
1989 Porsche 944
1981 Triumph TR7
1989 (?) Alfa Romeo Milano
1993 Saab 9000
san rensho is offline   Reply With Quote
Old 01-18-2014, 03:47 PM   #12
98 Arctic silver 986
 
tommy583's Avatar
 
Join Date: Jul 2011
Location: Upstate, NY
Posts: 1,313
Garage
I feel like i actually helped . I hope it works out for you. I read on the forum somewhere that the ICV is also a VW or Audi part that looks exactly the same for much cheaper.

tommy583 is offline   Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -8. The time now is 06:05 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Content Relevant URLs by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page