main relay

We may earn a small commission from affiliate links and paid advertisements. Terms

zackzerr

New Member
ok so to start off i have a 89 hatch. did the mpfi conversion. i put a zc mini me in it. when i tried to start it i had no fuel pump. also had no spark. i jumped the pump and it works. i checked for power to dizzy and have power. but no spark. the guy i got the car from attempted the mpfi conversion and wired injectors to the wrong side of ecu plug A(a11-17) so i cut that apart and wired it up right. now i think im having a problem with the wiring to the main relay. i checked continuity from the yellow and black wires on the A plug. i have it to the main. i also checked all corresponding colors from main to ecu all is fine. i hear the main click once but it does not prime the pump. has anyone had this issue? im pulling my hair out. plz help..... oh and im using a p28 with boomslang and dizzy jumpers. its a zc block completely stock witha built to the brim z6 head. crower cams and valvetrain. i did timing myself and even rechecked it like 5 times since. even ignition timing is perfect
 
Is the distributor an MPFI distributor?
All sensors correct?
Plug wires right?
Check all wiring again.
Open main relay and make sure there are no cracked solder joints- if there are, reflow with a soldering iron.
Head TDC and block TDC match?
 
when you jumped the fuel pump did you jump it at the relay or at the pump itself?
 
Is the distributor an MPFI distributor?
All sensors correct?
Plug wires right?
Check all wiring again.
Open main relay and make sure there are no cracked solder joints- if there are, reflow with a soldering iron.
Head TDC and block TDC match?

i checked the main and there are no cracks. i took the one out of my integra and still the same. yes plug wires are in order. even pulled cap to make sure. yes the dizzy is mpfi. its a obd1 z6 dizzy. i checked all wiring again. have continuity on all wires from ecu to main. when i put the engine together i made sure it was perfectly in time and spun the engine over by hand many times and rechecked timing.
 
when you jumped the fuel pump did you jump it at the relay or at the pump itself?

yes i jumped it straight from battery to pump worked good. i took the return line off and pumped the old fuel out. put good gas in and pumped more. then hooked it all beck up
 
Try jumping the fuel pump wire at the main relay and see if it works. I had a problem like this on the first mpfi swap that I did. It ended up being the wire that the ecu grounded for the fuel pump side of the main relay was broken. I think it was black with green stripe if I remember.
 
today i checked continuity on the wire from main to fuel pump and have continuity from terminal 7 on the main to all 4 wires at pump is this right?
 
Last edited:
well i started inspecting my boomslang jumper and realized there are two wires broken off. its on the obd0 side of harness and if you are looking into the plug it would be the last two on the bottom of clip c. i think this is tdc sensor and cyl position. would this keep me from getting fuel? i kno it would stop spark
 
Last edited:
today i checked continuity on the wire from main to fuel pump and have continuity from terminal 7 on the main to all 4 wires at pump is this right?

I will check a wiring diagram for that at work tomorrow but i don't think that is correct.
 
awesome. i fixed my boomslang so im goin to put it in. i also noticed my main makes a weird noise after it clicks. kind of like a short buzzing sound
 
So the yellow/black wire on the main relay should send power to the injectors and to the fuel pump. It should only have continuity to the yellow /black wire on the pump and injectors. If the relay is buzzing that usually indicates a poor ground connection
 
guess i have a short somewhere between main and pump. that would be only reason for it to have continuity to the grounds. right?
 
well from the wiring diagram i found on google for the 89 civic says that the two yellow/blk wires from ecu plug A go to main. so at my main they are wired together and also i have a blk/red wire next to it. that is not wired up. what would that be? on the on the diagram it says its not used. i wonder if the ecu plug was changed
 
Last edited:
Strobe signals from the dizzy (not sure which signal and don't want to look it up unless it will help you) can cause the injectors not to fire as they are triggered from the distributor to ECU. The injectors fire at the intake stroke and ignition fires on the compression stroke - as such they are independently triggered from different sensor signals relative to crankshaft position.
 
Last edited:
ok kind of a dumb question but should my injectors have a resistor box wired up? they have a different clip than my integra. could these be odb2? guy said they were h22 injectors. i have them wired up to a resistor as of now.
 
There are no dumb questions bro. Learning is learning and assistance is assistance. Don't assume on the injectors. Pull them and check part numbers on them. Running resistors on Saturated Injectors won't fry anything but won't run right if it runs at all. You should confirm what they are. Systematically eliminate potential problems.
 
ok well i know the injectors have a notch in the middle for the plug where my injectors for the obd1 teg have them in the top corners. isnt there a way to test if they are saturated or peak and hold by using a ohm meter?
 
im going to test injectors today. how does the ground work in the ignition switch? the column would have to be bolted up right?
 
Back
Top