Fusible Link - not final fix (1 Viewer)

[FJ80Dad]

My original thread: Fusible Link, no start advice

I was able to track down a bad/fried FL. I was unable to find any other problem(s) so I installed a new FL and started right up. Daughter drove about 1 mile and same problem, fried FL-AM2

Condensed version: 1995 with 275,000. Worked well until last wk when it stalled. Cranks over, no start, no spark, no CEL. New EFI relay (Old one within spec as well) No blown fuses. I have not been able to identify any shorts in the circuit or wear on the harness. If I jump the FL with a low amp fuse I do get the CEL with key on.

With the new FL - started right up, ran well and was at idle for a good amount of time. Started at least 15 times before I let my daughter take a test spin, which ended after about a mile.

I have one more FL - bought 2. I am looking for trouble shooting advice on what is causing the problem before I waist another FL

Thanks, Mike

 

[blkprj80]

FL AM2 looks like it feeds only the ignition.
I have the EWD for a 1996, which should be fairly similar to your 1995.
AM2 feeds the coil and the igniter via a Black/Red wire, downstream of your ignition switch. It also feeds a 7.5A IGN fuse.
Ah, the Black/Red wire(s) also feed all of your injectors. Injector harnesses are known to get shorted at the back of the engine in the harness where it passes dangerously close to the EGR pipe. Check your harness in that area, it may be shorted. Also check the wires that feed your distributor (igniter?) and the coil. Maybe something has rubbed through the insulation somewhere.
Most likely cause is a short in the injector supply at the EGR pipe, start there.

 

[FJ80Dad]

Thanks - will look again at that area

 

[Reelitchy]

Hey, just saw your post and remembered it from the other day.
in your post from the other day you said...

No spark
No CEL
new EFI relay (still no CEL)
burned out Fusible Link - FL-AM2 white wire to gray connector
disconnected AFM - still no CEL
good power to fuse box
12v to EFI relay #2, no 12v to #3 with key on
multimeter shows continuity from ground to 1,3,4 on EFI relay plug (does this indicate short?)

You shouldn't have continuty on 1,3 and four all together. Only one pin should be grounded but i can't remember which one (the others are shorted) and don't have the diagram in front of me. Looks like you have an intermittant short on your efi relay wiring. Check this thread --- titled RTH - no start originated by newtomelx.
check the bundle from under the relay = up beside the dist and to the back wall on the engine comp. There is some good info on what you should have at the efi relay connection.. good luck

 

[FJ80Dad]

I will check that again tomorrow - I was thinking that at the time. Thanks for the heads up on the other post - will read. On a string of a few night shifts so my schedule is a little off right now

 

[Reelitchy]

There is a connector at the distributor with 2 wires I believe. A yellow red and red yallow . Disconnect and make sur there is no ground on all four pins. This way you can isolate firewall side or to the fuse block. Sounds intermittent so you may need to shake the harness on the side your checking. Just food for thought- if you replaced the canister with a gm canister and didn't remove the lower strap - it will rub that harness right under the fuse block.

 

[FJ80Dad]

The only wires I could find going to dizzy was 4 wire connector W R G L. all showed continuity - W R G all the same resistance L (blue) was lower but looking at EWD it looks to have diff routing.

Pulled the EFI relay and checked where it plugs in and found 1 is ground and is good. No continuity at 3 which is normal. I do have continuity between 1 and 4 and 4 and neg batt terminal - 4 completes the circuit with 2 (always hot) so should it show continuity or does this indicate a short?

also check connector just behind dizzy it looks like one Y-R. Female side no continuity, male side with continuity - looking at the EWD this Y-R goes every where - so not sure what these findings indicate and I'm working with about 45 min sleep so little fuzzy

 

[blkprj80]

I must be missing something if you're going after the EFI side of things.
FL AM2 doesn't feed the EFI circuit. FL MAIN does, through the 15A EFI MAIN fuse.
You said you don't have a CEL which further confuses me. Will it light up, with a good link, with the engine not running but key on?

FL AM2 is 0,3mm which is AWG22, which is a 5A link.
It feeds the 7.5A ignition fuse and the Black/Red (black w/ red stripe) wire also goes to all the injectors. The ECU pulls the other side of the injector to ground to pulse it.

I'm looking at section K of my EWD, the overall electrical part, in the "Power Source" and "Engine Control" sections.

Another place to check, although a pain, is the harness to the ECU under the dash. I've heard there are some sharp edges that can cut into a harness up under there.

 

[Reelitchy]

Pin four of the efi socket should not have ground- only pin one should have the ground

 

[Reelitchy]

The ground closes the relay and then I believe 12 volts should go thru othe side from the ecu and that voltage goes back to the ecu and many other circuits. I don't have diagram right now

 

[FJ80Dad]

Thanks for the input - sorry for the late response. I will be back at it today.

blkprj80 - yes the CEL does light with a good connection, however when starting (it will now start) it will blow FL AM2 (or a fused bypass). Sorry about the confusion - when I first got the "no start, no CEL" I pulled the EFI relay to check. I then found the problem with FL AM2. Since it starts and then burns out FL AM2, I don't think I need to worry about the EFI relay or socket

The 7.5A ignition fuse is fine and the socket shows continuity. I will look at all the wires going to the injectors. I did see the post showing the problem under the dash but did not think it could apply to my issue - but with your explanation of the injector to ECU wiring that sounds plausible

 

[aamiggia]

Did you ever sort out the problem?

I'm having the exact same thing as of yesterday on my '97. FL AM2 (white w/ red wire) blew, then fused jumper blows when engine is very warm. IGN fuse is OK, EFI relay is clicking with jumper in place and cold engine. I noticed a burn / melted wire smell from the ECU.

 

[95LCMachine]

I would like to hear if this was ever resolved as well. I ran into the same issue this last week (8 miles out on forest service roads).
I hope to have it nailed down this next long weekend.

Please let us know what you found!
Thanks

 

[tjones8]

Ever figure this out?