Notices
86-95 Trucks & 4Runners 2nd/3rd gen pickups, and 1st/2nd gen 4Runners with IFS

wont start when its cold

Thread Tools
 
Search this Thread
 
Old Dec 27, 2008 | 12:17 PM
  #21  
thook's Avatar
Registered User
 
Joined: Sep 2005
Posts: 8,656
Likes: 16
From: NW Ark on wooded ten acres...Ozarks at large!
When you turn the key to ignition, a red rectanguler light on the dash instrument panel that says "engine" should come on. It let's you know that the ECU and EFI system is getting voltage.
Reply
Old Dec 27, 2008 | 05:57 PM
  #22  
poody81's Avatar
Thread Starter
Registered User
 
Joined: Dec 2008
Posts: 13
Likes: 0
i dont have a red engine light but i do have a orange check engine light that does not come on when it is acting up but when it does work that light does come on with the key in the on position. i went out to try to start it and it would not start but i left the key in the on position for about a half hour and it started right up
Reply
Old Dec 27, 2008 | 07:03 PM
  #23  
poody81's Avatar
Thread Starter
Registered User
 
Joined: Dec 2008
Posts: 13
Likes: 0
if the light is not comming on does that mean my computer is acting up or is it not getting power to the computer where do i go from here
Reply
Old Dec 27, 2008 | 07:24 PM
  #24  
abecedarian's Avatar
Registered User
 
Joined: Mar 2008
Posts: 12,723
Likes: 6
From: Temecula Valley, CA
Originally Posted by yota4runna
If you look at the circuit diagram above, you'll see that the fuel pump gets its power thru the Circuit Opening Relay. That relay is behind the right kick panel above the computer. The Circuit Opening Relay is turned on when the Fuel Pump Switch inside the Air Flow Meter closes as you crank the engine, and the moving plate inside the AFM opens. Maybe your problem is that under severe cold the plate in the AFM isn't moving. You can test the fuel pump and bypass the AFM switch by using the Check Connector [passenger side fenderwell under hood] to turn on the Circuit Opening Relay using a paper clip. With the ignition On, jumper between the Fp and the +B terminals in the Check Connector with a paper clip. This should turn the fuel pump on and you should hear the fuel flowing in the lines under the hood.
In that drawing, the ignition switch supplies voltage to the contact portion of the COR, to one of the magnetic coils in the relay, and to a noise filter (the resistor / capacitor) across that coil. The other coil in the COR is supplied voltage by the ECU STA wire and grounds elsewhere. In function- the ECU powers one of the coils during cranking; the other coil is only activated whent the airflow through the AFM is sufficient to close the contacts in the AFM and ground the coil. The noise filter basically prevents any electrical noise from the AFM bouncing open and closed while cranking from inducing interference elsewhere in the wiring and causing problems such as momentarily turning the COR off and interfering with the ECU.
Essentially, trying to start the vehicle or having the engine running (and drawing air through the AFM) should both turn the COR on and activate the fuel pump.
I'm going to check the drawings for an 87 and see if they do in fact match this drawing to a tee. However, functionally, the systems work the same- COR is turned on by cranking and/or by airflow through the AFM.
Reply
Old Dec 27, 2008 | 07:30 PM
  #25  
poody81's Avatar
Thread Starter
Registered User
 
Joined: Dec 2008
Posts: 13
Likes: 0
i tired jumping the fuel pump from diagnosis port but i couldnt get the fuel pump to turn on
Reply
Old Dec 27, 2008 | 07:36 PM
  #26  
abecedarian's Avatar
Registered User
 
Joined: Mar 2008
Posts: 12,723
Likes: 6
From: Temecula Valley, CA
you did that with the key on?
Reply
Old Dec 27, 2008 | 07:38 PM
  #27  
poody81's Avatar
Thread Starter
Registered User
 
Joined: Dec 2008
Posts: 13
Likes: 0
yes i did
Reply
Old Dec 27, 2008 | 07:40 PM
  #28  
abecedarian's Avatar
Registered User
 
Joined: Mar 2008
Posts: 12,723
Likes: 6
From: Temecula Valley, CA
have you tried jumping directly from the battery + terminal to the FP terminal in the box?
Reply
Old Dec 27, 2008 | 07:43 PM
  #29  
poody81's Avatar
Thread Starter
Registered User
 
Joined: Dec 2008
Posts: 13
Likes: 0
havent tried that yet ill have to give that a try in the morning
Reply
Old Dec 27, 2008 | 09:37 PM
  #30  
thook's Avatar
Registered User
 
Joined: Sep 2005
Posts: 8,656
Likes: 16
From: NW Ark on wooded ten acres...Ozarks at large!
Wait a minute.....the FP and B+ terminals in the box, as Abe describes, is in the diagnostic port as you describe that you've already tried but could not get the fuel pump to work that way. Hmmm.....conundrum.
Reply
Old Dec 27, 2008 | 10:26 PM
  #31  
abecedarian's Avatar
Registered User
 
Joined: Mar 2008
Posts: 12,723
Likes: 6
From: Temecula Valley, CA
Originally Posted by thook
Wait a minute.....the FP and B+ terminals in the box, as Abe describes, is in the diagnostic port as you describe that you've already tried but could not get the fuel pump to work that way. Hmmm.....conundrum.
B+ should only be hot with the key on, which he didn't try.
Reply
Old Dec 27, 2008 | 10:33 PM
  #32  
thook's Avatar
Registered User
 
Joined: Sep 2005
Posts: 8,656
Likes: 16
From: NW Ark on wooded ten acres...Ozarks at large!
Wait another minute....I got confused. Derf!!

You were saying "directly from the battery terminal". I thought you meant the B+ terminal in the diagnostic box.

Oh, and he did say he tried with the key on at the diagnostic port. He just didn't try directly from the battery to FP port/diagnostic box....which wouldn't require the key.

...sorry. <<<ignore me>>>

Last edited by thook; Dec 27, 2008 at 10:36 PM.
Reply
Old Dec 27, 2008 | 10:43 PM
  #33  
abecedarian's Avatar
Registered User
 
Joined: Mar 2008
Posts: 12,723
Likes: 6
From: Temecula Valley, CA
Yeah, then I derf'd... he tried it B+>FP with key on... didn't try straight from batt...
/me slaps self
Reply
Old Dec 27, 2008 | 10:47 PM
  #34  
thook's Avatar
Registered User
 
Joined: Sep 2005
Posts: 8,656
Likes: 16
From: NW Ark on wooded ten acres...Ozarks at large!
/me slaps abe...then slaps self.

/sin slaps us both.

/both drink some Irish cream and go to bed.

/'nighty night......zzzzzzzzzzzzzzz
Reply
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
bigjstang
86-95 Trucks & 4Runners
21
Jun 2, 2025 03:56 PM
BushPig
Tires & Wheels
4
Oct 29, 2022 06:26 AM
Doug4320
86-95 Trucks & 4Runners
19
Mar 24, 2018 10:11 PM
Jonny246
86-95 Trucks & 4Runners
4
Jul 12, 2015 04:51 AM
Poncho0206
95.5-2004 Tacomas & 96-2002 4Runners
3
Jul 10, 2015 06:21 PM




All times are GMT -8. The time now is 02:45 PM.