 No Start Help Requested Please, 1975 1.8 L-Jet no start after 10 minute soak |
|
|
|
Porsche, and the Porsche crest are registered trademarks of Dr. Ing. h.c. F. Porsche AG.
This site is not affiliated with Porsche in any way. Its only purpose is to provide an online forum for car enthusiasts. All other trademarks are property of their respective owners. |
|
|
| rbzymek |
 Jun 18 2019, 05:46 PM
Post
#1
|
|
Member  Group: Members Posts: 199 Joined: 5-April 19 From: Northville, MI Member No.: 23,013 Region Association: Upper MidWest 
 |
So this is a conversion from a carb which was running great with the new FI. I had just installed an AFR meter and was adjusting the AFR to about 13:1 during a 30 minute run. Stopped at the grocery store and had a crank with no start after a 10 minute soak. The harness is newly fabricated, rebuilt AFM from AutoAtlanta, gas in the tank, I do have spark, fires with starting fluid, fuel pump runs when vane is moved, have power to the ECU, no difference with second ECU, voltage to the injectors with key on, new Pertronix III dizzy with Flamethrower III coil, have fuel pressure (40 psi), throttle switch doing what it is supposed to, AFM voltage output varies with movement, Air temp thermistor in AFM is in range, CHT reads 2.2 K ohms.
I'm kinda running out of ideas. Got any???? Thanks! Ray |
   |
 
|
  |
Replies
| JeffBowlsby |
Jun 20 2019, 07:40 AM
Post
#2
|
|
914 Wiring Harnesses & Beekeeper Group: Members Posts: 8,968 Joined: 7-January 03 From: San Ramon CA Member No.: 104 Region Association: None
|
Ljet injectors ‘ground’ through the resistor pack. The wires on the resistor pack frequently break off at the resistors and this condition is easy to inspect.
|
 |
|
| rbzymek |
Jun 20 2019, 07:59 AM
Post
#3
|
|
Member Group: Members Posts: 199 Joined: 5-April 19 From: Northville, MI Member No.: 23,013 Region Association: Upper MidWest
|
QUOTE(JeffBowlsby @ Jun 20 2019, 07:40 AM)  Ljet injectors ‘ground’ through the resistor pack. The wires on the resistor pack frequently break off at the resistors and this condition is easy to inspect. Jeff, Yes, I understand that a broken wire at the pack can shut it down. I believe that the power is routed from the FI relay to the resistors then to the injectors. The other side of the injector goes to the module where a transistor grounds it to turn it on. Last night I put a scope on each side of one injector and found that I was intermittently losing power to the injector when cranking. When I placed a jumper from B+ to the main resistor pack feed the car fired up and ran. Woohoo! Later today I will place all four scope channels on the dual relay to determine the root cause. Thank you for your suggestions. I will let you know what I find. Regards, Ray |
|
|
|
Posts in this topic
rbzymek No Start Help Requested Please Jun 18 2019, 05:46 PM
JeffBowlsby 40 psi fuel sounds high, did you verify that with ... Jun 18 2019, 07:11 PM
rbzymek
40 psi fuel sounds high, did you verify that with... Jun 18 2019, 07:24 PM rbzymek
40 psi fuel sounds high, did you verify that wit... Jun 18 2019, 07:45 PM ndfrigi I believed 1.8 FI should only have between 28 and ... Jun 18 2019, 07:45 PM ndfrigi maybe flooded with gas? did u try starting it whil... Jun 18 2019, 07:52 PM timothy_nd28 I had a similar condition on mine, hard start cond... Jun 18 2019, 07:53 PM ndfrigi finally Tim is here and he will definitely can hel... Jun 18 2019, 07:56 PM rbzymek
finally Tim is here and he will definitely can he... Jun 19 2019, 01:15 PM rbzymek
finally Tim is here and he will definitely can h... Jun 19 2019, 03:48 PM Dave_Darling Power to the injectors comes from the dual relay, ... Jun 20 2019, 04:48 PM JeffBowlsby Our own Jim Hoyland documented the dual relay test... Jun 20 2019, 05:03 PM rbzymek
Our own Jim Hoyland documented the dual relay tes... Jun 20 2019, 05:32 PM |
1 User(s) are reading this topic (1 Guests and 0 Anonymous Users)
0 Members:
|
Lo-Fi Version | Time is now: 4th July 2025 - 11:40 PM |
Invision Power Board
v9.1.4 © 2025 IPS, Inc.