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Got a Civic 1992 hatch b16a2 turbo , yesterday the car completely died while driving
(check Engine light came on) and the car wouldent start,
Now im in the garage trying to find out what happend.
First thing i noticed is that the fuel pump doesent run the first 2 seconds when you turn the key.
Tried to connect my laptop to my ECU (running Hondata) but it doesent seem to get any Power to the ECU? so i cant read out the fault code.
Do you Think it could be the main relay that died all of a sudden?
The starter does run when i turn the key and lights etc works perfect.
Best regads
EDIT: i have tested all relays and checked the big ones underhood aswell and they all are fine.
Check the 4 small ECU ground wires that go to a lug on the thermostat. Does CEL come on when you turn the key on? Generally if it's a bad main relay the CEL will come on and stay on, if no power to ECU it will not come on. Also the oil and battery lights should be on with key on and engine not turning.
Have been working on the car today again
it seem like some wiring have been worn or so i dont know, cant find really.
The 15A fuse underhood pops all the time as i turn IGN to on (while the main relay is connected) not when i have removed the connector to the main relay.
when i use my mulitmeter on continuity all connections on the main relay harness beep without battery 12v and the number "7"
if i connect the the main relay without putting IGN to ON and connect battery to fuel pump connector on the relay it runs all the time without poping the fuses.
all harness looks fine, have done the troubleshoot that honda have in the servicebook.
nu sure where to start to search for this fault or should i just rewire it all?
Unplug the fuel pump, turn on ign. if fuse does not blow, replace fuel pump, if it still blows, replace PGM-FI Main Relay.
Make sure fuel pump power lead, is not damaged, [pinched] between the relay and fuel pump.94
if this dosent work then open the main relay and take pictures. 99% of all main relay problems can be fixed w/o getting new. (at least in my experience.)
Likely a short to ground in the engine harness or with the parts Ron mentioned. You can probably just ohm the yellow and black wire to ground as you unplug stuff rather than trying to energize it and blowing fuses.
So i have tested some more stuff.
Fuse 31 pops ASAP i turn IGN to 2 even with the whole ECU disconnected.
also if i disconnect the fuel pump
I have tried with 3 different Main relays now (from working cars)
Disconnected all4 fuel injectors, IACV and the O2 sensor heater (did cut the White Cable "D" 14 on my ECU harness to check if it worked)
However, the fuel injector power fuse is a 12V constant, and switching is done in the PGM-FI Main Relay, out put for that power goes to, like you said, the injectors, ECU IGP 1 and 2 and heated 02. it also powers the coil on the fuel pump relay, in the PGM.FI Main Relay.
It is obvious that the problem is after the PGM-FI Main Relay, but not the relay itself, the problem must be the fuel injector relays output, black/yellow I think, with everything else unplugged, injectors 02, IACV, that only leaves IGP1 or 2 to the ECU/ECM or the wiring between the PGM-FI Main Relay and tgwe ECU. 94
The injector circuit of the main relay pulls in whenever the key is on. The ECU only has control of the fuel pump circuit, so even with ECU unplugged, the "hot" side of the injectors will power up at key-on if the main relay is plugged in. So I'd agree with fcm, it is something after the main relay, which I think only leaves the injectors and their immediate wiring. With main relay and ECU unplugged, there should be no path to ground (infinite resistance) from the injector circuit.
Next step might be to unplug the engine harness from the car harness by disconnecting the two big plugs on either side of the engine.
Problem solved i think removed the interior panels everywhere made a brand new harness and problem was fixed ^^ feels good to have a real solid smoldered harness now with fresh cables.
I guess it was something between the PGM FI relay and the ECU (probably the yellow and black cables)
So the fuel pump primes now and check engine lamp goes off after 2-3 secounds after ive put on IGN and no fuses gets blown.
The car wouldent start now anyways i think the tune in my hondata got lost after all the strugles so gotta get my tune mailed to me (made 463whp on 1,4 bars boost on E85) last saturday :D
Yeah one thing, is the PGM FI main relay pin number "3" those 2 Cables go straight to A25 and B1 connector? or are they for something more? cuz car wont start but ECU gets Power and pump primes etc
Yeah i will take a look at it after work again, but for example would fuse 31 be able to pop even tho O2 Sensor, Injectors, ECU and the IAVC is all disconnected if its a short? after the relay that is?
04-17-2016, 07:04 AM
Car wont start (main pgm fi relay?)
