#1 fuel injector plug not working

[speedygonzalez]

I really need help on this one!! i just recently rebuilt my 87 n/a MR2 motor. it cranks, but engine sputters and the rpm is bouncing. the timing is set to factory specs. just found out that the #1 fuel injector plug is not working. i checked with a multimeter and i'm reading 3 ohms, but when i checked the pins inside the connector with a tester (continuity), the light bulb does not turn on. so i figured that is not gettin 12v. i checked the two wires inside the plug all the way and they are not broken or damaged. the two wires inside the plug are 1 black and 1 green with red stripes. the black wire is routed to the starter while the green with red stripes is connected to the "start injector time switch" plug. i checked the injector time switch pins with the multimeter and is reading 40 ohms according to my haynes book specs. so i know that switch is working. also, i replaced the ECU for a new one and still not working. I give up!! what the heck is going on!! i would really appreciate it if somebody would give me advice or help me on this issue!!

[Luni]

It might be a ground issue.

Ground your meter to chasis and probe both pins for presence of 12v at the plug with the ignition turned on.

[speedygonzalez]

i did, but doesn't get 12v. also, i checked all grounds and they are cleaned and tight. it only reads 3 ohms.

[mr2_mk1.5]

ok, for starters the injector you are talking about is the cold start injector, the black wire should only have power when the key is turned to the crank position and the green wire should only have ground when the engine is cold, the only purpose of that injector is to give the engine a little shot of extra fuel when cranking cold. the injectors are driven in teams of two, 1&2 and 3&4, the ecm controls the ground pulse while a switched 12 volt (key on) supplies voltage to the injectors through a resistor pack, the way to check the injector pulse is by using a noid light which you can get from the parts store and sticking it into the injector harness and watch if it flashes while the engine cranks over, but it won't work on the cold start injector, the first thing I would check though is for vacum leaks followed by checking for leaking injectors especially the cold start injector and also pull the vacum line off of the pressure regulator and check if theres gas in the line indicating a ruptured diaphram, if all is good so far pull off the fuel return line from the line going to the tank, dropping the return line into a container and jumping B+ and FP in the diagnostic terminal and seeing how much fuel comes out and apply vacum to the regulater and if the flow doesn't increase then the reg is shot and causing exssecive fuel pressure and leaking past the injector pintle, also check the resistance at the injector resistor it is located on the firewall in front of the battery unplug it and check resistance from where the black/white wire goes to the other two terminalsyou should have 2-3ohms on both terminals also the injector resistance should be 1.5-3 ohms and check them with the wiring harness disconnected that isn't the spec for the cold start injector though you should have 3-5ohms and maximum leakage allowable is less then one drop per min. If your still passing the checks check the fuel pressure, you should be getting 33-38psi with the regulator vacum hose disconnected, engine running and the pressure gauge installed into the rail at the cold start injector and should drop to 28psi with the hose connected.if this still tests out ok check the flow of fuel, I had similar problems on an 85 and my pressure specs were dead on but I was only getting something like .5L a minute flow, I'm not sure what the stock spec is but it should be at least a couple liters a minute, if you end up having to do a fuel pump change the wiring from the tank to the car, I've seen this harness fail multiply times and nothings worse then dropping the tank on a two twice. If its still not running right check your coolant temp switch and airflow meter, its also advisable to check codes just to be safe. I hope this helps you and you get your car up and going

[mr3]

Threads 8 months old.

[mr2_mk1.5]

I know, I never noticed untill after I posted, don't worry I feel like an idiot