Won't run unless I pull the fuel pump fuse - Page 4 - Rennlist - Porsche Discussion Forums

Notices

Won't run unless I pull the fuel pump fuse

Old 10-10-2018, 10:36 PM
  #46  
Dan Martinic
Addict
Rennlist Member
 
Dan Martinic's Avatar
 
Join Date: Aug 2017
Location: Toronto, Ontario, Canada
Posts: 1,118
Default

Yeah, I should know better
Dan Martinic is online now  
Old 10-11-2018, 12:27 AM
  #47  
Humboldtgrin
Addict
Rennlist Member
 
Humboldtgrin's Avatar
 
Join Date: Jun 2014
Location: NORTHERN CALIFORNIA
Posts: 1,992
Default

30 years ago they had very few problems besides having to many zero’s behind the first number when purchasing one.
Humboldtgrin is offline  
Old 10-12-2018, 03:14 AM
  #48  
Droops83
Addict
Rennlist Member
 
Droops83's Avatar
 
Join Date: Feb 2003
Location: Santa Barbara, CA
Posts: 1,144
Default

Originally Posted by Jacob AbuKhader View Post
Chris, thanks for the input. Since testing the injector harness I went through every single sensor harness plug yesterday and tested looking for any shorting or signs of an issue and couldnít find one, even with the disgusting shape the harness for the speed and ref sensors the numbers are still bang on.

I physically pulled each injector and tested them direct to the battery and they each clicked.

Half of the sensors are new or replaced and the others have outputs within spec so if it is electrical I agree with you and Dan that itís gotta be a DME.

I didnít know that unplugging the AFM makes the DME run a different air fuel map. Even with my new one unplugging it helps the idle. So if it runs good on one map, their could be internal damage in the DME circuitry on the regular map.

I finally found someone whoís got a DME they are willing to lean me to test out so that should be a pretty definitive test.

Once the cars running, Iíll treat her to an injector cleaning lol and a new set of tires since mine are now lopsided from sitting.
Under normal conditions, the engine stalls if you disconnect the AFM while running . . . . but of course the engine will also stumble and stall if you pull the fuel pump fuse under normal conditions! So, no "different map," just a symptom of your over-fueling issue.

Originally Posted by Dan Martinic View Post
Wow cool info Chris, thanks.

Curious... when testing one injector connector while the others are plugged in, my reading is even +12V both pins. With all plugs disconnected, the same plug drops to 10V on one side; not as drastic as Jakob's, but a drop nontheless. Normal?

I'm chasing a long-running issue that is slight but... perhaps the infant stages of something Jacob is getting.

Looking forward to the DME swap test!
I'm not sure I would read into that too much if your car is running well for the most part. Jacob's running issue is a very unusual situation of fuel injectors being stuck open somehow, while yours is a typical slight running issue of a 30+ year old 951!
Droops83 is offline  
Old 10-12-2018, 08:40 AM
  #49  
Dan Martinic
Addict
Rennlist Member
 
Dan Martinic's Avatar
 
Join Date: Aug 2017
Location: Toronto, Ontario, Canada
Posts: 1,118
Default

Originally Posted by Droops83 View Post
yours is a typical slight running issue of a 30+ year old 951!
Yes, keep forgetting that part
Dan Martinic is online now  
Old 10-26-2018, 07:24 PM
  #50  
Dan Martinic
Addict
Rennlist Member
 
Dan Martinic's Avatar
 
Join Date: Aug 2017
Location: Toronto, Ontario, Canada
Posts: 1,118
Default

Hey Jakob.. I finally cleaned out the AFM and did the "bend the contact to a new spot on the carbon strip" thing. Seems to have fixed my issue and generally improved throttle response. Big change!

Just reminds me how something on these old cars can 'test' good yet still be off. Did you try the DME yet?
Dan Martinic is online now  
Old 10-26-2018, 07:28 PM
  #51  
Jacob AbuKhader
User
 
Jacob AbuKhader's Avatar
 
Join Date: May 2018
Posts: 155
Default

Originally Posted by Dan Martinic View Post
Hey Jakob.. I finally cleaned out the AFM and did the "bend the contact to a new spot on the carbon strip" thing. Seems to have fixed my issue and generally improved throttle response. Big change!

Just reminds me how something on these old cars can 'test' good yet still be off. Did you try the DME yet?

Glad to hear that!

Unfortunately no... drove out to the other car and it wouldnít start. Couldnít even test the DME. Iíve been trying to find a way to show where the fault is, injectors or DME. My bleed down is fine by my symptoms are those of leaking injectors.
Jacob AbuKhader is offline  
Old 10-26-2018, 11:23 PM
  #52  
Dan Martinic
Addict
Rennlist Member
 
Dan Martinic's Avatar
 
Join Date: Aug 2017
Location: Toronto, Ontario, Canada
Posts: 1,118
Default

Yikes.. sorry to hear progress has stalled
Dan Martinic is online now  
Old 10-29-2018, 12:16 AM
  #53  
Jacob AbuKhader
User
 
Jacob AbuKhader's Avatar
 
Join Date: May 2018
Posts: 155
Default

Originally Posted by Dan Martinic View Post
Yikes.. sorry to hear progress has stalled
Dan if I pulled the injectors and they open and close, and the car passes bleed down test with flying colors, is it safe to say that they arenít the issue? Everyoneís saying that leaking injectors will cause the pressure to drop too quick but my FP is dead on so Iím kinda confused if they could still be causing my over fueling.
Jacob AbuKhader is offline  
Old 10-29-2018, 10:39 AM
  #54  
Dan Martinic
Addict
Rennlist Member
 
Dan Martinic's Avatar
 
Join Date: Aug 2017
Location: Toronto, Ontario, Canada
Posts: 1,118
Default

Replace the FP and do the cup test
Dan Martinic is online now  
Old 10-29-2018, 10:42 AM
  #55  
Jacob AbuKhader
User
 
Jacob AbuKhader's Avatar
 
Join Date: May 2018
Posts: 155
Default

Originally Posted by Dan Martinic View Post
Replace the FP and do the cup test
FPR is new. Wilco on cup test Iíll charge up and give that a shot this week and report back with results. 👍🏻
Jacob AbuKhader is offline  
Old 11-04-2018, 09:16 PM
  #56  
Jacob AbuKhader
User
 
Jacob AbuKhader's Avatar
 
Join Date: May 2018
Posts: 155
Default

Alright well I couldnít do either because the battery is so dead the car wonít start. Oil was fouled anyways so I threw in a new set of plugs and changed the oil to save the bearings and keep testing. I thought I had done a proper job replacing the AOS seals but apparently I didnít because oil just came pissing out of that bottom o ring as fast as I was filling it. Gonna revert to what my old engineering teacher told me. K I S S. Keep it simple stupid. That seal is obviously causing my rich issue or at least contributing to it. Oil leaking into airbox and no start issue showed up at about the same time so.

In anycase ill get it sorted and Iíll get back to everyone for anyone still following.
Jacob AbuKhader is offline  
Old 11-05-2018, 08:27 AM
  #57  
Dan Martinic
Addict
Rennlist Member
 
Dan Martinic's Avatar
 
Join Date: Aug 2017
Location: Toronto, Ontario, Canada
Posts: 1,118
Default

I remember changing AOS seals and feeling like it doesn't fit. I didn't try to force it in; rather, I just put the AOS on an torque-wrenched the fastener. Seems to be holding up. It is a funny fitting o-ring
Dan Martinic is online now  
Old 11-05-2018, 12:16 PM
  #58  
Droops83
Addict
Rennlist Member
 
Droops83's Avatar
 
Join Date: Feb 2003
Location: Santa Barbara, CA
Posts: 1,144
Default

Originally Posted by Jacob AbuKhader View Post
Alright well I couldn’t do either because the battery is so dead the car won’t start. Oil was fouled anyways so I threw in a new set of plugs and changed the oil to save the bearings and keep testing. I thought I had done a proper job replacing the AOS seals but apparently I didn’t because oil just came pissing out of that bottom o ring as fast as I was filling it. Gonna revert to what my old engineering teacher told me. K I S S. Keep it simple stupid. That seal is obviously causing my rich issue or at least contributing to it. Oil leaking into airbox and no start issue showed up at about the same time so.

In anycase ill get it sorted and I’ll get back to everyone for anyone still following.
Leaking AOS seals are definitely a problem, but any leak in the breather system is a vacuum leak, which would cause a LEAN condition. Your over-fueling problem is a separate issue.

Oil leaking into the airbox? Well, I dunno about that. I guess you have to re-seal the AOS anyway, so start there and then circle back to the over-fueling issue.
Droops83 is offline  
Old 11-05-2018, 12:36 PM
  #59  
Jacob AbuKhader
User
 
Jacob AbuKhader's Avatar
 
Join Date: May 2018
Posts: 155
Default

Originally Posted by Dan Martinic View Post
I remember changing AOS seals and feeling like it doesn't fit. I didn't try to force it in; rather, I just put the AOS on an torque-wrenched the fastener. Seems to be holding up. It is a funny fitting o-ring
Iím so relieved you said that I did not like that ring on there it seems loose on the AOS and too tight to squeeze into the fitting and it seemed okay nothing was leaking initially. Luckily pelican sent me a spare so Iíll redo it.


Since I gotta pull the intake off again Iím just gonna knock out injectors to eliminate them. I canít test them because he battery is so dead I have to jump the car to even get it to crank. When it runs it only runs on 2 or 3 cylinders even with the fresh oil it was so rich the smoke was fogging up my whole damn neighborhood lol. I changed plugs as well and when removing the old set they were soaking wet with gas.

Thanks for all the advice guys. Iíll get back to ya within the next few weeks.
Jacob AbuKhader is offline  
Old 11-07-2018, 01:43 AM
  #60  
Humboldtgrin
Addict
Rennlist Member
 
Humboldtgrin's Avatar
 
Join Date: Jun 2014
Location: NORTHERN CALIFORNIA
Posts: 1,992
Default

Regarding a leaking vacuum line, it will cause a lean issue up until a lean misfire happens. Then raw fuel dumps into the exhaust and tells the O2 sensor it’s running rich when it’s really lean. Then the DME will try to lean it out more creating more of a lean missfire issue. Also what injectors are you using? Stock 4.5 ohm injectors? If your using low impedance injectors you’ll want to use two 1 ohm resistors for each batch fire fuel injector harness. If you use low impedance injectors without resistors it will eventually overheat the DME drivers (there are only two) and basically destroy your DME. Not that this is your issue but you want to rule that out.
Humboldtgrin is offline  

Thread Tools
Search this Thread
Quick Reply: Won't run unless I pull the fuel pump fuse


Contact Us Advertising Cookie Policy Privacy Statement Terms of Service

© 2018 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: