Pennock's Fiero Forum
  Technical Discussion & Questions
  Intermittent No-Start Issue

Post New Topic  Post A Reply
Email This Page to Someone! | Printable Version


next newest topic | next oldest topic
Intermittent No-Start Issue by PatrickTRoof
Started on: 01-20-2021 02:35 PM
Replies: 14 (251 views)
Last post by: PatrickTRoof on 02-22-2021 11:23 AM
PatrickTRoof
Member
Posts: 561
From: Baltimore, MD, USA
Registered: May 2013


Feedback score: N/A
Leave feedback

Rate this member

Report this Post01-20-2021 02:35 PM Click Here to See the Profile for PatrickTRoofClick Here to Email PatrickTRoofSend a Private Message to PatrickTRoofEdit/Delete MessageReply w/QuoteDirect Link to This Post
Lately my 1985 GT 2.8 has developed a random no-start issue which acts like a bad ICM (no spark or tach signal). Sometimes it will do it on a cold start, other times if the engine has already been running.
At first I thought I was eating up ICMs for some reason, but then sometimes it will then start up again. I've even seen it crank for a second with no tach signal, then suddenly catch and fire right up. Sometimes
I've fixed it by swapping in a known good ICM, which will fix the problem until next time, but I've swapped in ICMs which I had thought were bad from a previous case of this happening, and it fired right up. And once
it's running, it never cuts out. The only thing I can think of is it might be the 2 wire connector between the coil and the ICM. The ignition coil and pickup coil are only a few months old. As noted above, the ICM is
one of a few new or good ones I've put in it recently.
IP: Logged
PFF
System Bot
theogre
Member
Posts: 29669
From: USA
Registered: Mar 99


Feedback score: N/A
Leave feedback





Total ratings: 553
Rate this member

Report this Post01-20-2021 02:52 PM Click Here to See the Profile for theogreClick Here to visit theogre's HomePageSend a Private Message to theogreEdit/Delete MessageReply w/QuoteDirect Link to This Post
ECM won't run EFI is has ignition problems or just "think so."
See my Cave, HE Ignition & Ground "Myth" notes

ECM can be "dead" and still look good.
Bad solder joints anywhere can make engine not start/run but won't set "Codes" because thinks no problems.
Example: L4 TBI driver "transistor" can have problems and not turn on even tho ECM command this to happen and won't set codes.
Related: See my Cave, ECM Heat

Suggest you clean/fix all ground in engine bay and more and coat ends w/ brake or silicon grease.
See my Cave, Wire Service

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)


The Ogre's Fiero Cave

IP: Logged
PatrickTRoof
Member
Posts: 561
From: Baltimore, MD, USA
Registered: May 2013


Feedback score: N/A
Leave feedback

Rate this member

Report this Post01-20-2021 03:18 PM Click Here to See the Profile for PatrickTRoofClick Here to Email PatrickTRoofSend a Private Message to PatrickTRoofEdit/Delete MessageReply w/QuoteDirect Link to This Post
All of my engine bay grounds are good, and I've added a couple extra ones too.
IP: Logged
fierobear
Member
Posts: 27026
From: Stuck in the People's Republic of Kalifornia
Registered: Aug 2000


Feedback score: (2)
Leave feedback





Total ratings: 383
Rate this member

Report this Post01-22-2021 02:39 PM Click Here to See the Profile for fierobearClick Here to Email fierobearSend a Private Message to fierobearEdit/Delete MessageReply w/QuoteDirect Link to This Post
Is the car an automatic?
IP: Logged
PatrickTRoof
Member
Posts: 561
From: Baltimore, MD, USA
Registered: May 2013


Feedback score: N/A
Leave feedback

Rate this member

Report this Post01-22-2021 11:34 PM Click Here to See the Profile for PatrickTRoofClick Here to Email PatrickTRoofSend a Private Message to PatrickTRoofEdit/Delete MessageReply w/QuoteDirect Link to This Post
No, it's a 4 speed.
IP: Logged
Mike in Sydney
Member
Posts: 288
From: Meadow Flat, NSW, Australia
Registered: Sep 2011


Feedback score: N/A
Leave feedback

Rate this member

Report this Post01-23-2021 06:37 PM Click Here to See the Profile for Mike in SydneySend a Private Message to Mike in SydneyEdit/Delete MessageReply w/QuoteDirect Link to This Post
Have you checked the clutch interlock switch? It's near the bend in the clutch pedal. I think you can jumper the yellow and purple wires together to by-pass the switch. BE CAREFUL. CAUTION. DANGER, WILL ROBINSON, doing this will let the car start while in gear.

[This message has been edited by Mike in Sydney (edited 01-23-2021).]

IP: Logged
Patrick
Member
Posts: 31298
From: Vancouver, British Columbia, Canada
Registered: Apr 99


Feedback score: (1)
Leave feedback





Total ratings: 446
Rate this member

Report this Post01-23-2021 08:05 PM Click Here to See the Profile for PatrickClick Here to Email PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post

In order for the OP not to get confused by various suggestions, I think it's worthwhile to clarify that the engine is turning over but randomly not starting. This rules out safety switches in Park (with autos) or with the clutch pedal (on manuals).

 
quote
Originally posted by PatrickTRoof:

Lately my 1985 GT 2.8 has developed a random no-start issue which acts like a bad ICM (no spark or tach signal)... I've even seen it crank for a second with no tach signal, then suddenly catch and fire right up.

IP: Logged
PatrickTRoof
Member
Posts: 561
From: Baltimore, MD, USA
Registered: May 2013


Feedback score: N/A
Leave feedback

Rate this member

Report this Post01-24-2021 07:58 PM Click Here to See the Profile for PatrickTRoofClick Here to Email PatrickTRoofSend a Private Message to PatrickTRoofEdit/Delete MessageReply w/QuoteDirect Link to This Post
The clutch safety switch is already bypassed in my car.
IP: Logged
PatrickTRoof
Member
Posts: 561
From: Baltimore, MD, USA
Registered: May 2013


Feedback score: N/A
Leave feedback

Rate this member

Report this Post01-26-2021 03:28 PM Click Here to See the Profile for PatrickTRoofClick Here to Email PatrickTRoofSend a Private Message to PatrickTRoofEdit/Delete MessageReply w/QuoteDirect Link to This Post
I've recently replaced the 4 pin connector to the ICM, as well as the grey connector to the coil (white and pink wires). Next I will replace the white and pink wire connector from the coil to the dizzy, because I just checked it and the white wire has cracked insulation, and it is a replacement.

I just received a Matco ICM tester, and decided to try it on a "bad" ICM (no start or tach signal), but it tested good. I'm really scratching my head now.
IP: Logged
olejoedad
Member
Posts: 14529
From: Clarendon Twp., MI
Registered: May 2004


Feedback score: (5)
Leave feedback





Total ratings: 192
Rate this member

Report this Post01-26-2021 07:09 PM Click Here to See the Profile for olejoedadClick Here to Email olejoedadSend a Private Message to olejoedadEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Mike in Sydney:

Have you checked the clutch interlock switch? It's near the bend in the clutch pedal. I think you can jumper the yellow and purple wires together to by-pass the switch. BE CAREFUL. CAUTION. DANGER, WILL ROBINSON, doing this will let the car start while in gear.



The clutch safety switch only interrupts the starter solenoid trigger signal.
Everything else would work, but no crank.
IP: Logged
Oregon88
Member
Posts: 129
From: Willamette Valley Oregon
Registered: Feb 2016


Feedback score: (1)
Leave feedback

Rate this member

Report this Post01-27-2021 12:55 PM Click Here to See the Profile for Oregon88Send a Private Message to Oregon88Edit/Delete MessageReply w/QuoteDirect Link to This Post
I dealt with a similar issue on my 88GT for a few years and chased a few different things down with no luck.

I eventually replaced the distributor and all my problems went away.
(Crosses fingers and knocks on wood)
How old is your distributor, cap, rotor?
IP: Logged
PFF
System Bot
PatrickTRoof
Member
Posts: 561
From: Baltimore, MD, USA
Registered: May 2013


Feedback score: N/A
Leave feedback

Rate this member

Report this Post01-27-2021 04:11 PM Click Here to See the Profile for PatrickTRoofClick Here to Email PatrickTRoofSend a Private Message to PatrickTRoofEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Oregon88:

I dealt with a similar issue on my 88GT for a few years and chased a few different things down with no luck.

I eventually replaced the distributor and all my problems went away.
(Crosses fingers and knocks on wood)
How old is your distributor, cap, rotor?


I replaced the distributor with a newer one that a PFF member sent me a while ago, maybe within the last two years. It only had a few miles on it because he did a 3800SC swap. It's in decent shape. The cap and rotor are less than a year old, as I did my usual tune up recently. I may end up getting a brand new
distributor if this keeps up.
IP: Logged
PatrickTRoof
Member
Posts: 561
From: Baltimore, MD, USA
Registered: May 2013


Feedback score: N/A
Leave feedback

Rate this member

Report this Post02-21-2021 04:58 PM Click Here to See the Profile for PatrickTRoofClick Here to Email PatrickTRoofSend a Private Message to PatrickTRoofEdit/Delete MessageReply w/QuoteDirect Link to This Post
Update: the car had been doing fine for a while, though I hadn't been driving it much. Then yesterday it started acting up again. It didn't want to start on the first try, then fired right up on the second.

I drove around doing some errands and it seemed fine. Later I picked up a buddy and we went to work on his Fiero. Leaving there it didn't want to start again. We swapped in the coil connector from his car, with no luck. Put the other one back in and it eventually started.

Later on it wouldn't start at all. I tested the ICM and it was good. So I took a small screwdriver and bent the metal tabs in on the pickup coil connector to make them fit more tightly, and it fired right up.

I don't know if I fixed it or if it just decided to work again. We'll have to see. Next step would be a new dizzy.
IP: Logged
Spoon
Member
Posts: 3459
From: Sadsburyville, PA. 19369 / USA
Registered: May 2004


Feedback score:    (16)
Leave feedback





Total ratings: 60
Rate this member

Report this Post02-21-2021 07:01 PM Click Here to See the Profile for SpoonSend a Private Message to SpoonEdit/Delete MessageReply w/QuoteDirect Link to This Post
PatrickTRoof, Before getting a new dizzy listen to my story. I have a 86 2.8 SE 4spd with a little over 55k at the time of my trouble. It always started but on occasion it would just shut off while driving along in 4 gear but it would always start right back up and run perfectly. I did all the usual checks just short of spending any money and all components of the ignition were okay.
I suspected a bad connection between the ICM and the ECM. I started at the ECM harness. With engine running I used a non-conductive item and began poking at each wire on the ECM connectors. At this stage I wasn't even sure what wire(s) were responsible for the ignition. Then it happened, I push against a wire and the engine hesitated but kept running. I teased it some more ever so slightly and was able to stop the engine from running. BINGO!!! I believe it was a white wire on one of the ECM connectors. I pulled the wire from the connector and strengthen up the pin by bending it to fit tighter.
Repeated the test and end of problem. That was back in the early 2000's and never had a problem since. A few years ago I did the 3800sc swap and made my own harness so I'd at lease learn a lesson on how things work..

Spoon

------------------
"Kilgore Trout once wrote a short story which was a dialogue between two pieces of yeast. They were discussing the possible purposes of life as they ate sugar and suffocated in their own excrement. Because of their limited intelligence, they never came close to guessing that they were making champagne." - Kurt Vonnegut

IP: Logged
PatrickTRoof
Member
Posts: 561
From: Baltimore, MD, USA
Registered: May 2013


Feedback score: N/A
Leave feedback

Rate this member

Report this Post02-22-2021 11:23 AM Click Here to See the Profile for PatrickTRoofClick Here to Email PatrickTRoofSend a Private Message to PatrickTRoofEdit/Delete MessageReply w/QuoteDirect Link to This Post
That's a very good call. I will look in the shop manual asap and find the pin for the correct wire.
IP: Logged

next newest topic | next oldest topic

All times are ET (US)

Post New Topic  Post A Reply
Hop to:

Contact Us | Back To Main Page

Advertizing on PFF | Fiero Parts Vendors
PFF Merchandise | Fiero Gallery | Ogre's Cave
Real-Time Chat | Fiero Related Auctions on eBay



Copyright (c) 1999, C. Pennock