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Discussion Starter · #1 ·
so here it is... dec 26th truck had top end torn down to the heads... the re-assembled... started and test drove fine... i had surgery and hadent tried to start it until last week (prior to this i had problems with a broken FP connector that was shorting out)

truck started then died... after that no FP... no prime...nothing...i havent touched the truck for a month and it was fine last time i did

fast forward to today and yesterday...
new gas tank and mustang 255lph pump are in... was reading 8.9V at the FP wiring on the frame rail side... then as soon as i connected that wiring to my pump wiring, the power dissapeared... after that, anytime i connected the wiring to anything(including my siphon pump, a seperate FP with just wire leads to it) the power would dissapear and id have 0 volts...

went up front and check out FP relay... i was having a grounding problem as far as i could tell... stripped the ground wire on the FP relay back and "T"'d it over to the battery ground post... turn key and FP fires right up... hmmm...
Anyone know where the fuel pump relays ground goes to??? like where it terminates???
So i noticed all the ground wires to the ground strap under the d-side hood hinge were crap... i yanked them all back to clean wire, re-soldered and re-grounded... that ground should be good now... however the FP wouldnt fire unless i had that T on the FP relay ground... if i pulled off the wire that jumped the FP relay ground to the battery the FP wouldnt work...

continued below


AAAAAAAAAAAAAAAAAAAAAAAAAAAAHHHHHHHHHHHHHH I FOUND IT~!!!!!

So by total mistake tonight i found the issue that caused all of this headache... i was setting the timing and looked down to see an orange wire..(at the end of the thread i talk about disconnecting an orange wire at the fender and the whole system works...) this orange wire is twisted with two other wires... the orange wire has bare wire showing...
closer inspection: i find the orange wire popping right out of the back of the TPS sesnor... directly out of the TPS sensor is 3 wires... two of them being the orange wire, and a black wire... BOTH are bare wire for the first 1/2" coming out of the tps...and they are coiled right on top of each other!!!!!!
i push the black wire up off of the orange, reconnect the orange wire into the black connector on the wheel well... and she fires right up... found my short... it was just that crappy wiring that had pulled out of the tps and grounded to eachother... i must have spun the connector 180 and twisted them together when i re-installed them

ill be picking up a new TPS tommorow. :D
 

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Discussion Starter · #2 ·
so me and my buddy decide well lets start it... so we replace the jumper wire on the FP relay to the battery ground and try and start it... it cranks and cranks and cranks and nothing happens... not even a puff of smoke... YES, we have fuel at the rails...

so he hops up and puts the mutimeter to the coil connector... 3 volts... WTF!!!???
so if i pull the FP relay jumper ground the FP wont work... and right now i have no spark... basically the whole wiring system is down... wtf... truck cranks fine...has interior lights...didnt try radio... but just everything under the hood is running at low voltage

ECU problem?? grounding problem???

question for electrical geniuses... verify all ground strap locations under hood for me please

1. Battery to frame to lower engine block
2. Firewall(pside above and left of MAP sensor) to upper manifold pass side
3. Firewall below wiper motor thing to coil bracket

????????

theres one wire coming from the main wiring harness down under the ECU at the firewall(engine side) that goes up and terminates to the little ground screw behind the vaccum pump... however its not coated...just bare wire coming from the harness... maybe got hot???

any help greatly appreciated.... everything worked fine before... now ive got nothing

dc
 

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Discussion Starter · #3 ·
ughhh... im not even sure if we grounded the FP relay ground now...looking at steves writeup... i think the wire we grounded was green w/ a stripe... ill check in a few...

i didnt know FP relay talked to EEC relay

can anyone lay out the order for me???
EEC PWR
30 - Y (always 12V)
87 - Bu, DB, R (out to EEC)
85 - Wh/LB, R/LG (12V in from ig.sw.)
86 - Bk/LG, Bk (ground)

FP
30 - Y (always 12V)
87 - Pk/Bk, Br, DG/Y (out to inertia sw.)
85 - R (12V in from EEC PWR relay)
86 - T/LG, LB/Or (ground from EEC)

power comes in to EEC relay from ign(85)
then out to EEC (87)
then in to FP relay(85)
the out to inertia then to FP

right???

so where does the groudn terminate???

i ahve a feeling ill be cutting the harness open tommorow to track a ground :cry
 

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Are you getting power across the relay terminals? it could be a bad relay. Also make sure your grounds are really good. might want to replace them with a bigger ground. without being there i cant really help you out, i have a hard time diagnosing electrical gremlin in person, caue electrical intimidates me for some reason.

good luck man and follow though when you figure it out
 

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Discussion Starter · #6 ·
alright.... FP doesnt prime when the relay is grounded(jump grounded to the batt)... it just stays on...

the relays seem good... i tried grounding the EEC relay too... im gonna pull the connector off the EEC and trace where each ground goes... pin 20, 40, and 60... all grounds...

basically from what im getting every problem i have( FP relay ground, coil etc) all ground through the EEC... ill check the EEC grounds now

dc

ill double check and clean all other grounds from engine to firewall etc...

dc

still cranking...no spark... ill check Voltage @ coil again

dc
 

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Discussion Starter · #7 ·
re-did the grouding at the core support... it was a problem... my FP now works without the jumper t ground on it... evferything seems to work fine

except i have no spark...can tell if the coils working yet... and my voltmeter just died... reading 10v not touching anything lol

dc
 

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Discussion Starter · #8 ·
back to square one... i thought the FP was running fine... the jumper wire for the FP and the EEC relay grounds were touching...without those two jumped together the FP wont run

also... FP doesnt run a prime cycle... it just runs with key on... constant

still no spark... 12v at coil... tried swapping coils... 3v ref out other side(pass) of coil connector... no spark.

im so lost

dc

am i missing something simple like a resister etc???

heres what ive done:
*Replaced and/or cleaned Batt to frame to engine ground
*replaced the wire from coil bracket to firewall
*replaced intake manifold to firewall(pass side)
*tapped into EEC ground pins 20,40,and 60... they run through harness across core support and tie *into battery ground... tapped into them and made 12g secondary grounds at d-side fender
*repalced and cleaned battery to core support ground..
*swapped coil
*swapped ECU
* replaced coil connector

same thing with the fuel pump... if i tap into the ground wire at the relay and either ground it, or tie it into the EEC ground... the fuel pump works... take that off and i get nothing... fuel pump doesnt prime though, just turns on and stays on w/ KEY ON...

im lost and frustrated... the weirdest part is nothing happened that i did to make the truck this way... it started and drove to were it is now... sat for 3-4 weeks... and now does nothing except crank

as far as the coil... d-side is + pass side of connector is - ... or is pass side a volt ref to pin 4 IDM and the coil grounds through the bracket??

:cry

dc
 

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Discussion Starter · #10 ·
ok thanks for the info with the coil and relay...
ill check the EEC ground... but any idea why the ECU isnt telling the FP to cycle at all??? or why no spark or should i just be prepped to trace the problem down manually

ill work on it more tommorow

dc
 

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Discussion Starter · #11 ·
ive gotta pick up another haynes manual today...my chiltons just doesnt cover the areas i need...

im still looking for a few threads involving the FP relay not being triggered... ill have to track them down...cant find them yet...
the weird thing there is i tried swapping ECU's... however i had never tested the one i tried swapping in(its a JY ecu)

ill keep digging... itd be nice if it was just ignition... but im still having that relay issue... i have to check for codes still too..

dc
 

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Discussion Starter · #12 ·
update... i used a paper clip to jump the EEC relay from ign ON to EEC power out... then used another paper clip to jump the FP relay from EEC power in to inertia switch out...
turned the key on and the pump fires up(so EEC is sending the signal out to FP)... the fuel pump just stays on... doesnt run through a prime cycle... what gives??? the ECU controls the power to it for the prime cycle right??? or does the relay do that???(that doesnt make sense)

was holdng the coil wire in my hand and got shocked... so i dunno... dont know if spark was back temporarily or not at all... gotta check spark again now

dc

edit didnt get back to it tonight
 

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There is an ignition module on the side of the distributor isn't there? If that went bad/broken wire there, it could present those issues, except the FP priming part...:popc1:
I had the same problem with my first truck and it wound up costing me tons of parts and time until someone suggested this.

Easiest way to test is to take one out of a running truck. The auto parts stores (here anyway) cant test them.
 

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Discussion Starter · #18 ·
got some node(sp?) lights for the i njectors... there not firing...

i have good power at pin 1,37 and 57... the KA PWR, and the two V PWR wires going into the ECU... ive re-done and T'ed off to ground for extra assurance pin 20,40,and 60(all ground) fromt eh ecu...

ECU has good power and ground... however it is sending no ouput signals...
using test light i have no power at the ECT sensor... computer is not grounding the injector connectors... not sure if the coil is operational

i think i got voltage at the IAC though...dont know if thats relevant... both wires lit up..

so basically i have no injectors working to start it off...

i swapped ecu's... no luck

:cry
 
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