Intermittent starting and Pulsating at 2400 rpms - So close to getting it running (1 Viewer)

[Corky1936]

1994 fzj80. Did a complete tear down on the engine, sent to the machine shop and rebuilt the block and head. Replaced several of the connectors and checked the wiring harness and rewrapped it. Most of the wrap and wire looms were gone and wires were shorting out.

Started and ran pretty well, but took it to smog and it failed because at 2400 rpms it would pulsate down to 1800rpm then back to 2400. Had code 12 and 52. Broken wires to both knock sensors (missed how brittle they were) replaced both.
Afterwards:

1. Wouldn’t crank over. I don’t think it’s the park/neutral switch, though it could be. I do need to adjust it. It reads neutral on the dash when the shifter is just slightly pulled towards drive.
2. Then it’ll crank, but won’t start. I put the timing light on and didn’t get a spark reading.
3. Started, but immediately pulsated from around 1200 to 2000rpms.
4. Rechecked vacuum lines and connectors
5. No crank, then crank, but no start.
6. Got it to start, really didn’t do anything, idled around 600, but at 2400 rpm it starts to pulsate down to 1800, then back to 2400.
7. Then wouldn’t crank.
8. Got it to crank again, but won’t start.
9. Giving only code 12 now.
10. Ended evening with an Old Fashioned.

I don’t know what to check now. I haven’t done anything with the igniter. The distributor looks clean and well. The connector mounted to the side seems undamaged. I’m not sure if the starting issue is tied to the pulsating at 2400 rpms, or the occasional pulsating at start, which it only did initially.

Any of you subject matter experts (I’m in systems integrations and that’s a favorite saying ) that can help?
When I get through this, we are painting it.
Thank you all in advance. My daughter and I really appreciate all the knowledge on this forum.

 

[azusa]

How did it run before any of the engine work? Did you have any trouble codes?

 

[Corky1936]

When we purchased it, the rig would run intermittently with the instrument cluster fluctuating all over the place. It had grounding issues due to the poor state of the wiring harness. I was able to limp it home and started the disassembly right away. Never checked for error codes as I figured any would be unreliable.

 

[jonheld]

Keep in mind that the starter circuit is isolated from anything to do with the EFI system.
The only thing that affects both would be fusible links (power source). Every single EFI related item could be sitting in the driveway and the starter should still crank the engine.

 

[Corky1936]

Keep in mind that the starter circuit is isolated from anything to do with the EFI system.
The only thing that affects both would be fusible links (power source). Every single EFI related item could be sitting in the driveway and the starter should still crank the engine.

Good to know. I figured as much, but didn't know if the igniter had something to do with things getting messed up. I'm researching why it's surging at 2400 rpms. Maybe a vacuum leak somewhere. I can pull the throttle body and intake off and inspect all the lines if needed.
Thank you

 

[jonheld]

Good to know. I figured as much, but didn't know if the igniter had something to do with things getting messed up. I'm researching why it's surging at 2400 rpms. Maybe a vacuum leak somewhere. I can pull the throttle body and intake off and inspect all the lines if needed.
Thank you

The Toyota FSM and EWD are invaluable for all information. Free downloads in the resources section.

 

[Corky1936]

The Toyota FSM and EWD are invaluable for all information. Free downloads in the resources section.

Yes they are. I have the printed version and pdf version of the FSM and PDF of the EWD. I've been looking through them, and will do a deeper dive this weekend.

 

[azusa]

Sounds like you have a bad distributor, you need to do some test before you throw money at a distributor. Anybody around you have a distributor you can try out?