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Author Topic: 84 FJ1100 slight miss from 2800-3k rpm  (Read 784 times)
indyblue
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Location: Indy `O=o-
Posts: 75


Indy `O=o-


« on: September 06, 2022, 07:02:43 PM »

I have a slight miss between 2800 and 3k rpm at steady throttle.  Runs perfect above or below that or if I give a bit of throttle it goes away.

What should I be looking for?
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Indianapolis, IN `O=o-
1984 FJ1100, 39K mi., custom blue paint, K&N's, jetted, Supertrapps
2005 Pontiac GTO Impulse Blue M6 - gone
2012 Corvette Grand Sport Convertible M6 Crystal Red Tintcoat
1967 Firebird H-O Conv
Pat Conlon
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Gender: Male
Location: Sedona, AZ.
Posts: 9383



« Reply #1 on: September 14, 2022, 10:26:28 PM »

Electrical miss or fuel?
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1) Free Owners Manual download: https://tinyurl.com/fmsz7hk9
2) Don’t store your FJ with E10 fuel https://tinyurl.com/3cjrfct5
3) Replace your old stock rubber brake lines.
4) Important items for the ‘84-87 FJ’s:
Safety wire: https://tinyurl.com/99zp8ufh
Fuel line: https://tinyurl.com/bdff9bf3
indyblue
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Location: Indy `O=o-
Posts: 75


Indy `O=o-


« Reply #2 on: November 12, 2022, 08:41:52 PM »

Seems like spark since I know it is jetted a little rich.  Runs perfect in ever other rpm range.
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Indianapolis, IN `O=o-
1984 FJ1100, 39K mi., custom blue paint, K&N's, jetted, Supertrapps
2005 Pontiac GTO Impulse Blue M6 - gone
2012 Corvette Grand Sport Convertible M6 Crystal Red Tintcoat
1967 Firebird H-O Conv
Pat Conlon
Global Moderator
Gold Contributor

Super Hero Member
*****
Online Online

Gender: Male
Location: Sedona, AZ.
Posts: 9383



« Reply #3 on: November 12, 2022, 11:34:43 PM »

Intermittent electrical problems are a bitch. Does the 2,800-3,000 miss happen in all the gears, or just 5th?
Start with the simple stuff…step by step.
1) Unplug all your wire connectors, clean each side. Take the ground wire off your coils and engine, sand the connection.
Put new fuses in your fuse block.
Test
2)  Next, bypass your side stand stop switch. Often a problem. Follow the wires and unplug the connector and bridge the two wires together with a jumper wire.
Test
3) Next, bypass the right handlebar run/stop switch (happened to me, ** see below)
Test
4) Next, bypass the key ignition switch (hot wire it) A jiggly key and electrical contacts can cause an intermittent electrical power feed to your ignition box.
Test
5) Next, install fresh plugs, maybe one has a cracked insulator.
Test
6) Next, ohm check the resistor plug caps, maybe one is bad.
If you have the stock FJ plug wires it is highly doubtful they are bad. They are a stranded core stainless steel wire and are very durable, however once in awhile the resistor plug caps goes bad. If you have an aftermarket carbon core RF suppressor plug wires, all bets are off, those are not as durable and the oem FJ plug wire.

Start with the above 6 and report back…and then we will go from there.

Avoid the temptation of buying new parts (except plugs) until you know what’s wrong.

Hang in there….we will get it figured out.

** I had the same problem and it turned out to be a dirty run/stop switch that was causing an intermittent power interruption to the ignition box. I found this out by running a temporary jumper wire from the 12+ battery terminal directly to the ignition box, went for a ride and noticed the problem went away.

Cheers
Logged

1) Free Owners Manual download: https://tinyurl.com/fmsz7hk9
2) Don’t store your FJ with E10 fuel https://tinyurl.com/3cjrfct5
3) Replace your old stock rubber brake lines.
4) Important items for the ‘84-87 FJ’s:
Safety wire: https://tinyurl.com/99zp8ufh
Fuel line: https://tinyurl.com/bdff9bf3
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