Stumped

[Curveball97]

Need a bit of help, I have an 84 60 series with a full swap from a 88 62 series. Full drivetrain and interior swap on it. I’ve been having issues when it gets to operating temp not wanting to start after I shut it off while doing errands or just driving it. It will start up after sitting about 10-20 minutes. I’ve combed the mud forums and so far I have replaced the fuel pump, filter, pulsation dampener, pressure regulator, ignition coil, new cap, rotor, spark plug wires, spark plugs, and the efi relay. I’m still having the same issue, it runs perfect when it does fire up but if shut it down it needs 10-20 minutes to cool off before turning over again. Is there something that I am missing? Any help at this point would be a huge help.

 

[diesellibrarian]

This is my understanding: the 3F-E uses a Hall effect-style ignition system where "paddles" on the distributor rotor pass by a sensor, sending a signal to the ECU, which then signals the igniter (via the IGT and/or IGF? wires) to excite the coil, which of course sends spark to the spark plugs.

The 3F-E EFI system is really reliable, but as has been stated previously, it does rely on a number of sensors and other devices to be within spec. Some things can be brought into spec through adjustment (the TPS, for instance, or the distributor air gap), but others cannot (temp sensors, etc.) One thing that they all rely upon is a clean ground. It may be that you have some grounds that work ok when the engine is cold, but when things heat up, resistance increases. The igniter itself grounds through the coil mounting bracket: I actually ran a dedicated ground from the bracket mounting bolts to a clean ground on the firewall. Make sure your main engine/body grounds are clean and tight.

The 3F-E igniters are pretty reliable, so I would doubt that your problem lies there. There's no way to test the igniter (or the FSM doesn't list one, anyway), so in troubleshooting the ignition circuit, you basically eliminate all other possibilities (plug wires, air gap out of spec, timing, coil resistances, etc.), and if it's still not sparking, replace the igniter. Sadly the igniters are no longer available and can be tricky to track down, so hopefully it's not that.

 

[Curveball97]

This is my understanding: the 3F-E uses a Hall effect-style ignition system where "paddles" on the distributor rotor pass by a sensor, sending a signal to the ECU, which then signals the igniter (via the IGT and/or IGF? wires) to excite the coil, which of course sends spark to the spark plugs.

The 3F-E EFI system is really reliable, but as has been stated previously, it does rely on a number of sensors and other devices to be within spec. Some things can be brought into spec through adjustment (the TPS, for instance, or the distributor air gap), but others cannot (temp sensors, etc.) One thing that they all rely upon is a clean ground. It may be that you have some grounds that work ok when the engine is cold, but when things heat up, resistance increases. The igniter itself grounds through the coil mounting bracket: I actually ran a dedicated ground from the bracket mounting bolts to a clean ground on the firewall. Make sure your main engine/body grounds are clean and tight.

The 3F-E igniters are pretty reliable, so I would doubt that your problem lies there. There's no way to test the igniter (or the FSM doesn't list one, anyway), so in troubleshooting the ignition circuit, you basically eliminate all other possibilities (plug wires, air gap out of spec, timing, coil resistances, etc.), and if it's still not sparking, replace the igniter. Sadly the igniters are no longer available and can be tricky to track down, so hopefully it's not that.

Thank you so much for your reply, I’m in the process of tracking all of that down now and hopefully will have it figured out soon.

 

[Curveball97]

Update today, just adding a ground from the ignitor to the firewall made a world of difference. Had zero no start issues in the hour of driving and idling I did this evening. Thanks for the tip diesellibrarian

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[Bleu62]

I’m hoping this helps me as well.

 

[Curveball97]

I’m hoping this helps me as well.

I tied my ground into the wiper motor ground and have had zero issues driving it daily for the last couple weeks since the fix.

 

[diesellibrarian]

I tied my ground into the wiper motor ground and have had zero issues driving it daily for the last couple weeks since the fix.

Great news!

Since the coil bracket mounting bolts go through the inner fender, they are exposed to water and all kind of road grime that lessens their effectiveness as grounds, which is why I decided to run a dedicated ground wire. Glad it worked for you!