TFI upgrade, blown fuselink

Modified FSJ Tech Area

Topic author
Johnzi10
Posts: 256
Joined: Wed Nov 25, 2020 9:43 pm
Location: Northern Kentucky

Re: TFI upgrade, blown fuselink

Post by Johnzi10 »

I take your comments to heart! I’m too impatient for my own good. This Jeep is a hobby/project and I need to enjoy the process(you tube tutorial, look at TSM,etc).
This forum is a great community, as shown by members who watch new posts and respond(Stuka, you, Sirus, rocklawrence,let’s keep and others. It’s my problem that I get frustrated and put up semi coherent posts. My other Jeep is a 98XJ I’ve refreshed and use a lot. This older tech is not meeting my expectations as to ease of working on! No fun paying others to work on it! Does the forum have a therapy section?
2020 Cherokee Limited v6. Wife’s Jeep
2002 Grand Cherokee Laredo Daughters Jeep
1998 XJ Cherokee “the Ghost”
1989 Grand Wagoneer my Covid mental health medicine

Topic author
Johnzi10
Posts: 256
Joined: Wed Nov 25, 2020 9:43 pm
Location: Northern Kentucky

Re: TFI upgrade, blown fuselink

Post by Johnzi10 »

So, I’ve got fuselink, I think I will swap old coil back on the Jeep and see if fuselink fries again. That is the only real change I did, so I’ll try to see if it is causing the problem.
Makes me think HEI or DUI distributor might be the way to go if ECU with higher output coil is the problem. Or I have a circuit problem.
2020 Cherokee Limited v6. Wife’s Jeep
2002 Grand Cherokee Laredo Daughters Jeep
1998 XJ Cherokee “the Ghost”
1989 Grand Wagoneer my Covid mental health medicine
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tgreese
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Location: Medford MA USA

Re: TFI upgrade, blown fuselink

Post by tgreese »

Sounds like a good test. At most it will cost you an extra fusible link. What happens if it won't start? That would not be totally surprising.

DUI (Davis Unified Ignition) is a brand of HEI distributor. HEI is GM's name for their "unified" ignition. All HEI-type distributors for the AMC V8s are aftermarket products; no OEM HEI exists that fits the AMC V8. The Duraspark and the HEI are basically the same product from different manufacturers, but GM likely had a patent on putting the coil under the distributor cap. You can use the HEI module with the Duraspark distributor, and vice-versa. The HEI module with the Duraspark distributor is widely called "stealth HEI." That's what I'm running in my CJ-6.

The only thing "high energy" about the HEI is the coil. The magnetic design of the cylindrical coils is inferior to the rectangular EI coils. The Ford TFI coil is a similar device.

Also, the TSM was written as a manual for the dealership techs (known as "mechanics" in that era). It will not teach you how to work on cars. Anything a professional mechanic would know is assumed. If you want to learn modern car tech, your local community college likely has a program. For old cars, studying the trade books like the Haynes Techbooks https://www.amazon.com/s?k=haynes+techb ... _sb_noss_2 seems like a good approach.
Tim Reese
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Topic author
Johnzi10
Posts: 256
Joined: Wed Nov 25, 2020 9:43 pm
Location: Northern Kentucky

Re: TFI upgrade, blown fuselink

Post by Johnzi10 »

Thanks for the Haynes tech book lead! I use Haynes on XJ and ZJ. I got the old coil wired back in and fuse link holds. CRT Performace TFI upgrade kit. So I got a coil wire with proper leads to attach old coil to new distributor cap(larger). Runs without frying the link. Now have to pull plugs because they are gapped at .045 for the “hotter” coil, not .035 recommended for stock.
Any ideas as to why this supposed common upgrade caused a problem?
2020 Cherokee Limited v6. Wife’s Jeep
2002 Grand Cherokee Laredo Daughters Jeep
1998 XJ Cherokee “the Ghost”
1989 Grand Wagoneer my Covid mental health medicine

Topic author
Johnzi10
Posts: 256
Joined: Wed Nov 25, 2020 9:43 pm
Location: Northern Kentucky

Re: TFI upgrade, blown fuselink

Post by Johnzi10 »

So after swapping the coil and re gapping the plugs( with dry compression test, engine ran for 10 minutes. Next day, started it and backed it out of the garage, and it blew a fuse link. So much for coincidence. On to YouTube for my electrical tutorial!
2020 Cherokee Limited v6. Wife’s Jeep
2002 Grand Cherokee Laredo Daughters Jeep
1998 XJ Cherokee “the Ghost”
1989 Grand Wagoneer my Covid mental health medicine

sirrus
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Re: TFI upgrade, blown fuselink

Post by sirrus »

If it blew when you backed out, maybe there is a positive wire with cracked missing insulation touching body metal? It’ll short only when disturbed, like when working under the hood (TFI upgrade) or moving. Just a theory though
Sometimes we reinvent the wheel not to have more wheels but to have more inventors

1988 Grand Wagoneer - AMC 360 with ProFlo4 MPFI, TF727, NP229 FOR SALE
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Topic author
Johnzi10
Posts: 256
Joined: Wed Nov 25, 2020 9:43 pm
Location: Northern Kentucky

Re: TFI upgrade, blown fuselink

Post by Johnzi10 »

I had backed it out already, then saw the smoke. Wiring diagram shows the ignition switch at base of steering column is what I need to check. Self teaching on YouTube!
2020 Cherokee Limited v6. Wife’s Jeep
2002 Grand Cherokee Laredo Daughters Jeep
1998 XJ Cherokee “the Ghost”
1989 Grand Wagoneer my Covid mental health medicine

Topic author
Johnzi10
Posts: 256
Joined: Wed Nov 25, 2020 9:43 pm
Location: Northern Kentucky

Re: TFI upgrade, blown fuselink

Post by Johnzi10 »

I had backed it out already, then saw the smoke. Wiring diagram shows the ignition switch at base of steering column is what I need to check. Self teaching on YouTube!
2020 Cherokee Limited v6. Wife’s Jeep
2002 Grand Cherokee Laredo Daughters Jeep
1998 XJ Cherokee “the Ghost”
1989 Grand Wagoneer my Covid mental health medicine

Topic author
Johnzi10
Posts: 256
Joined: Wed Nov 25, 2020 9:43 pm
Location: Northern Kentucky

Re: TFI upgrade, blown fuselink

Post by Johnzi10 »

So, nooby mistake! The fuse link that was blowing was attached to a round connector with another wire from the alternator. When I replaced the fuse link I did not connect the wire. Fixed fuse link, now it runs, badly. The only difference is the bigger Ford distributer cap and adapter and Ford plug wires that came with the TFI coil upgrade.
Would the larger cap throw off the timing? It warmed up ok on the high idle cam but when kicked down it had a rough idle. I don’t own a timing light, thinking of just getting new plug wires ( I can’t put old ones back on) one oe cap and rotor and see if it will at least run as well as it did before.
2020 Cherokee Limited v6. Wife’s Jeep
2002 Grand Cherokee Laredo Daughters Jeep
1998 XJ Cherokee “the Ghost”
1989 Grand Wagoneer my Covid mental health medicine

Topic author
Johnzi10
Posts: 256
Joined: Wed Nov 25, 2020 9:43 pm
Location: Northern Kentucky

Re: TFI upgrade, blown fuselink

Post by Johnzi10 »

So the OEM distributor cap has it running properly again! Better actually with $137 dollar plug and wire change. TFI kit I can not use included. So much for my “upgrade” attempt.
2020 Cherokee Limited v6. Wife’s Jeep
2002 Grand Cherokee Laredo Daughters Jeep
1998 XJ Cherokee “the Ghost”
1989 Grand Wagoneer my Covid mental health medicine
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