hey g2ic I have the infamous crank no start problem, car has being doing this to me for a while now. when I put key on the ON POSITION the CEL goes on and the main relay does not click, car cranks but wont turn over. I put in a new relay thinking that was the problem but nothing, car wont fire. weird thing is that sometimes it will just go on randomly. (car has not fired up for about a week now) what could be the problem? I check for spark and it does spark. this no start issue only happens when CEL stays on.
things to know:
new main relay
new spark plug wires
new distributor
b20 swap done 5 years ago by previous owner
could it be a bad ground? where should I check?
could it be ecu?
does the fuel pump throw a check engine light? i don’t think my fuel pump is bad, its probably just the relay not clicking when CEL stays on
I check for voltage in all points and got a reading in all of them except No. 4 and No. 7
where should i go from here?
No. 4 was a blue cable with a white stripe and No. 7 was a yellow cable with a black stripe
my apologies. i got that all mixed up. ok. when testing this circuit, it must be live. that is, backprobe the connector with it hooked up to the relay. with the key on, backprobe pin 7. should be battery pwer. but will only last 2 seconds. i am assuming the schematic you’ve provided is for 92, as 90-91 is different i believe
with the key on, there will only be voltage for the first 2 seconds. with the backprobe pin inserted, cycle the key off then on. should be voltage for 2 seconds
remove the relay, apply power to pin 3 and ground to pin 8. while doing this,check for continuity across pin 5 and pin 7. if no continuity, replace the relay.
you see pin 8? that goes to the ecm. you need to find that pin on the ecm, then check for continuity between it and pin on the mfr connector. if continuity exists, replace the ecm. sorry, i don’t have a diagram handy. and i don’t necessarily trust that the one you posted is accurate. find the correct pin at the ecm and you’re golden
anyways, okay so i checked pin 8 on the main relay connector and pin 7 on ecm and there is continuity. Ill replace ecm but what should i replace it with ?? i currently have a pr4-a11 ABJ, I believe that’s the right one for my 92 LS but my car has a b20 swap what ecm should i have for this type of obd1 b20 set up?
you should probably just get an obd1 pr4 or p74/75 and run a chip designed for the 2.0swap. i’m sure there’s lots floating around. or you can try ramping up your pressure another 10psi or so. i’d prefer the chip though as this will be a complete reconfig. of your fuel and timing maps. wouldn’t be a bad idea to install a wideband too. cheap enough nowadays. always good to monitor afr
new ecm came in today, plugged it in and car started fine, cel is no longer on. thank you for the help welfare, now I can go back to building this beauty
