Intermittent death help (1 Viewer)

[Hammer45]

1989 desmogged FJ62. Before I tackle the engine removal I have to find the source of my intermittent stall. Sometimes it’s the No CEL no start and if all was good on startup then after varying drive times it will suddenly pop a CEL and completely die with no sign of starting or trying to start. No sputter or sign of fuel or spark. This is always remote on the side of the road. The kicker is that if I jumper the EFI MAIN relay leads, none of this happens. I can drive 200 miles and it starts, drives and repeat all day. So in laziness, I just jumper the EFI main every time I get in it but have to remember to remove it fairly soon or the battery dies. If I jumper the EFI relay after a sudden death, it starts and runs beautifully. Never returns a code. I suspect a short somewhere of course.

I have done the following to sort it out:
Fusible link delete
Replaced the corroded COR
tested the EFI MAIN relay, coil and igniter and all were within specs
Opened up the harness up to the level washer reservoir to replace and splice corroded wiring
The connector in the driver side rear quarter looks pristine

I appreciate your brains. I have reviewed the EFI diagnostics in the fsm and Jonheld’s summary as well. Any tips or suggestions for side of the road diagnostics?

Thx, hammer

 

[joebattle1]

Fuel pump relay maybe?

 

[Hammer45]

Fuel pump relay maybe?

Pretty certain there isn’t one! There is a connector in the driver rear quarter and the circuit opening relay in the front kick panel and the cutoff in the mass airflow sensor but no dedicated fuel pump relay I don’t think. Let me know if I’m mistaken.

 

[joebattle1]

I thought the 62’s had one. Im a 60 guy. What do I know.

Try reading through this thread. Maybe helpful…

FJ62 No Start Issue

First post here. I picked up a 223k mile FJ62 a couple months ago. Drove home approx 20 miles just fine. I did some pressure washing under the hood and then a cap, rotor, plugs, wires, and cleaned throttle body. Ran great. There was a mangled ground wire going from the air meter through the...

forum.ih8mud.com

 

[Hammer45]

I thought the 62’s had one. Im a 60 guy. What do I know.

Try reading through this thread. Maybe helpful…

FJ62 No Start Issue

First post here. I picked up a 223k mile FJ62 a couple months ago. Drove home approx 20 miles just fine. I did some pressure washing under the hood and then a cap, rotor, plugs, wires, and cleaned throttle body. Ran great. There was a mangled ground wire going from the air meter through the...

forum.ih8mud.com

Yeah I had been watching that too. Sounds like he did the same thing I did by simply jumping the larger wires at the EFI main relay. All seems fine then but it bypasses all the start logic and safety features of the MAF and COR. I just have to figure out how to catch mine while running and it suddenly dies and cuts everything off. Then see which relay or wire is sending bad feedback to the EFI main relay to shut it down. I can see the wiring on the diagrams but can’t get a grasp of what sends feedback to the EFI main relay.

 

[Hammer45]

I purchased a bunch of these posi tap T splice connectors to tap into the smaller wires just before and after the EFI main relay. I was planning on running these wires into the cab and attaching a Small LED so I can see what happens to the power supply during one of these stalls. These t splicing things just puncture the wire that’s tapped with a pointy tip so it can be temporary and I can maybe just use some liquid tape over the puncture when I move the splices and start to trace further along the wiring. Any thoughts about this plan?

 

[Hammer45]

I’m concerned a led will cause an easier way for juice to flow so I am going to get a better circuit tester with more resistance so I don’t blow up my ECM. WHATS A LITTLE WASTED MONEY

 

[Hammer45]

Well I am pretty sure I found my source of intermittent stall and no CEL, crank, no start. While prying off the rubber end cap to the connector for the EFI main relay (in order to back probe the connector), I found that the red wire, which is the thinner wire going to M-rel on the ECU, WAS BENT DOUBLE INSIDE THE CONNECTOR. This bend had continuity but was very loose and easy to bend. I think it was almost broken and causing a small source of resistance that caused the main relay not to engage intermittently. I used one of those low heat waterproof butt connectors with the solder with only an heat gun and wow, are they easy to use. I’ve driven about 2 hours and no stalling! So, I sent a message to @cruisermatt to see if we can get lined up for a new H55 swap, etc. lots to learn here