Fj40 DUI starts then dies

[txnight]

Picked up this '78 out of an estate. Truck was Not running and seemed untouched. Compressions were good so I went to wrenching.

DUI distributor.
Replaced carb with working unit.
Desmogged.
No ignitor or ballast resistor.

Symptoms: engine fires immediately, as soon as the key is moved into the run position it dies. Im certainly capable of making an easy mistake but i call myself installing the dizzy correctly and wiring it up as i have on other fj40's. Frustrating!

So, of i go a'testing. good spark, fuel pressure, 12v+ at the distributor in both the run and start position, ignition switch tests out, battery 14v, all the fuses replaced and tested.

Obviously there is something I'm missing
And I could really use some fresh ideas.

Thanks gentleman and Happy New Year

 

[Solace in Solitude]

DUI replaces the dissy, igniter and coil... have you removed the coil?

‘78 has an 8ga PINK Yazuki (sp?) resister wire spliced into the fat BY wire... is the pink wire the ballast resister you removed?

DUI timing is based at 12* BTDC and is tweaked even further BTDC... is your timing correct?

Spark plugs are typically gapped at .050-.055”... are they gapped correctly?

When I installed my DUI, I taped up the fat BY (not needed) and triggered a relay with the thin BY. Pulled full voltage from the battery, to the relay, and sent it to the DUI.

Edit: Happy New Year!!

 

[txnight]

Thanks for the quick response and excellent questions.

Coil is removed. The wire and the fender mount unit is removed.

Timing: I have it set on the BB which I believe is 7btdc.

No idea on the plug gap. Will check and report back.

I'm wired up to the big BY and I'm getting 12.8v to the dizzy.

Any chance you could take a photo or two of that side of the engine bay?

 

[Pin_Head]

The fat BY wire is the resistor on 78s. To test if this is the problem, hot wire the distributor directly to the battery and if it runs, then run a new wire from the key to the distributor. 12.8 V at the distributor doesn’t mean anything if it isn’t running because it is an open circuit.

 

[pjohnson]

^^^^ what he said.

I think your dizzy isnt getting enough juice in the run position. For mine, I ran all new wiring using a relay for main power directly from the battery.

 

[txnight]

Ok, here's a positive update.

Engine now fires up and idles roughly for 4-6 seconds. Adjusting the dizzy has the idle at what sounds like a normal rpm.

After 4-6 seconds it slowly dies and It backfires through the carb.

Maybe the carb isn't as good as I thought? Or maybe I have another issue, maybe both?

 

[Pin_Head]

Sounds like fuel starvation.

 

[Landlover12]

The fat BY wire is the resistor on 78s. To test if this is the problem, hot wire the distributor directly to the battery and if it runs, then run a new wire from the key to the distributor. 12.8 V at the distributor doesn’t mean anything if it isn’t running because it is an open circuit.

so I have been running a DUI for a few months on my 78 fj40 2f. Last night it suddenly died on me. I connected the ignition wire from the distributor direct to the battery and it started right up. Got it back to the shop. When I try to start the engine with the ignition wire from the DUI connected to the BY wire it will not start. When I connect to the battery it starts right away.

Voltage when tested not trying to turn the engine over on the BY wire

 

[Landlover12]

photos

 

[jmylie]

Ballast resistor? Vehicle starting but then stalling is a symptom of a bad ballast resistor.

 

[Landlover12]

Ballast resistor? Vehicle starting but then stalling is a symptom of a bad ballast resistor.

Doesn’t even kick over unless wires direct to battery

 

[Landlover12]

Thinking I’ll run a wire direct to the key

 

[Landlover12]

Going to run a new wire from the key to a solinoid next to the batt. That solinoid is going to connect the wire from the DUI distributor direct to the battery

 

[B y r o n]

HEI distributors will not work if a resistor is involved, they need 12V to the coil.

 

[Landlover12]

HEI distributors will not work if a resistor is involved, they need 12V to the coil.

Are they typically connected directly to the black and yellow wire or is there a solinoid going direct to battery?

 

[JohnnyC]

Did you check the engine/ignition fuse? Sometimes the fuse looks good but end disconnected (solder fail) … pull fuse and test with another fuse

 

[Landlover12]

Holly cow man! I just swapped out the fuse like you suggested and that did it

 

[Landlover12]

Thing fired right up

 

[Landlover12]

Crazy then all of the sudden it died

Started two or three times right up the. Never again. Connected the distributor wire direct to the battery and it started right away

 

[JohnnyC]

You’re saying it started to die again …. Correct?

If so

Either your blowing the fuse… or it’s not contacting correctly

Remove fuse block and clean it

If it’s still blowing fuse after then there’s an issue elsewhere in the line