Crank, no start; fuel pump not priming?

[kujito]

That might be it. I've got power at Fuel Pump Relay #30, but not at B Latch 30.

Time to go trace that one. I know it goes into a bundle that goes into another bundle.

 

[Shorty]

it appears to go from start relay down to first bundle and splits. One split should go to the latch relay "30" and the other looks to go to the yellow covered "diagnostic ports."

It should be "live" at "30" all the time (key on or off)

 

[kujito]

Working from the relays back, I found:

Orange wires from FPR 87, BLatch 30, small diagnostic port, spliced together with three more wires. Two of which, go back into a bundle towards firewall. The other goes forward thru a connector, and into another bundle forward around the battery and thru the header panel. Not sure where from there?

Edit:
pm'd ya

 

[87manche]

my experience is with an MJ, but I see no reason why AMC would have changed wire colors.
Orange is my fuel pump +, and the pump grounds to the drivers side tial light harness.

 

[Shorty]

based on '88 FSM diagrams:

powered wires off latch relay are pink-- they go to the diagnostic port and ECU pin B-10 to power ECU "latch functions"

powered wires off FP relay begin orange and split into orange/bk-- they go to:
- diag. connector (Or)
-ECU injector feeds pin C-11 and D-10 (Or)
-oxy. sensor heater relay (Or)
-----split------------
-EGR solenoid (Or/Bk)
-AC clutch relay (Or/Bk)
-fuel pump (Or/Bk)
-----connector "C-4"----------

the orange/black wire that enters connector C-4 is power back to the pump. Exiting this connector, it changes to a pink wire with a black tracer.


Just looking at the diagrams, it looks as though everything under hood is designated with an orange color and once power exits "C-4" it changes to pink/bk. I'll see if I can decipher where "C-4" is located and add that if successful.

 

[kastein]

C-4 confused me. I figured it was the ballast resistor (since it only has two terminals), but I don't know RENIX all that well.

 

[Shorty]

I've got Or/Bk on both sides of the resistor, so I'll assume it's farther down circuit. Still looking, though.

 

[kujito]

Thanks for all the help!

I'll have to get a look at it with better light and less rain. Might not be until Sat. morning though. I get home late and would rather play with my new daughter.

Chasing electrical gremlins in the rain makes me nervous anyhow.

I'll try to get it cleaned up a bit, and maybe get a few pics when I get back to it.

 

[kujito]

....oh, and yes, the orange fuse link for the B+ Latch Relay does connect directly from the B+ terminal on the start relay, so you should have 12V at terminal 30....

I may not have been clear on this point. In the current configuration, B+ (B Latch) #30 will only receive power when FPR #87 is hot. It comes from the ghetto fab splice I found (it was wrapped with duct tape). There doesn't appear to be anything from the Starter relay to B+ 30.

When FPR 87 gets power, it sends it TO B+ 30 and the Diagnostic port, then into the bundles/connectors mentioned above. No power to FPR 8 = No power @ B+ 30.

Maybe I missed it, but can somebody describe the sequence of events with respect to B+ and FPR relays, from key on to start? Where does power go first (or concurrently) when going through Key On/Run --> Start --> Key On/Run?

 

[kujito]

So, finally got back to it.
Going by the Haynes diagram/color coding, it looks like somebody changed around the relays. I do have 12V constant @ both B+ & FPR 30.

Re-read some earlier posts (Joe P. probably thinks I'm an idiot). I'm finally starting to catch up. I blame baby induced sleep deprivation
I do have 12V across ICM pins A/B.

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