I replaced timing chain, clutch &c a few weeks ago. Got the truck running and drove it several hundred miles. No problems (unless you count tracking down a mysterious slow coolant leak) except that the idle & timing were off.

So tonight I decided to take care of that. Got the idle set, hooked up the timing light, started the engine, and tried to jump T and E1 in the diagnostic connector. Per the manual, that should allow the timing to be set at the specified 5 degrees or so BTDC, and un-jumping it should retard it to about 20 BTDC. (If I'm remembering the numbers correctly...)

I couldn't get it to more than about 15, and jumping/unjumping didn't seem to have any effect. So I decided to test to see if the paper clip was actually making contact, by doing the code readout: turn off engine, jump the connectors, turn ignition on (but don't start), and count flashes. Except there's no check engine light at all, either with or without the jumper, and the truck won't start any more! Cranks ok, but doesn't fire.

I tried moving the distributor to several places in its range, didn't help.

The light and code readout did work a couple of weeks ago. Haven't yet removed the instrument cluster to check for a bad bulb (seems unlikely, though), but I don't see why that would keep it from starting.

Anyone have any ideas as to what the problem might be?

Truck is a 1988 4WD with 22RE engine.

 

Show us where you uses the jumper/paperclip.

Get your volt meter out and measure voltage supply to the ECU on b+. While your there you can measure voltage on the CEL/MIL, if the bulb is good you should have voltage (not excluding the wire being shorted to a hot wire somewhere), it's easier than pulling the dash apart.

 

B+ at the diagnostic connector is 0.18 volt. I don't see a connector for the check engine light on the diagnostic connector. Do I need to measure at the diagnostic connector, or the ECU unit itself? (The one behind the kick panel in the passenger side footwell.) There doesn't seem to be any way to get a voltmeter on it without pulling it out and stripping the wire...

 

Problem solved. It was a blown fuse. This thread was a help, even though it's for the V6: https://www.yotatech.com/forums/f116...t-come-190314/

 

I am glad you got the problem solved.

It does make me wonder what caused the fuse to blow in the first place, as fuses do not typically blow on their own.

Hopefully the problem will stay solved, but if the fuse blows again, update this thread and we can help find the issue.

 

B+ to E1 shorts the EFI circuit to ground, and would blow the fuse. Just be careful with that paperclip!

 

Yeah, the fact that it was running really puzzled me, and is why I didn't go looking at fuses right off the bat. Didn't seem like anything happened that would cause a fuse to blow.

Maybe I did accidentally short B+ to E1. I think I was using the wrong sort of paper clip :-)

 

So you had to replace the EFI fuse?

Oxygen sensor is on that fuse, iirc no time to look, it can short to the transmission area and worth inspecting the wiring.