Injectors wont fire

[Number1gkid]

Hi i posted about a month or so ago about a problem i had and i was told to get a new ecu so i did and now 1 of 2 of my problems was solved.The first problem was that the fuel pump was not recieving power.The new ecu fixed that.the second problem is that the injectors arent firing.my mechanic told me that if i take the plug off the injector and have someone try and crank it the light should flash everytime that injector is supposed to fire.well the light does not flash.any help would be much appreciated i really need to get my car on the road.im sure you will need to know this info as well.its a 1990 plymouth laser with a 1.8L and automatic transmission.

 

[AwdEi]

Make sure all of the harnesses are connected that have something to do with firing (coil pack, cam angle sensor, etc.).

 

[Number1gkid]

checked all that and it didnt help.any other ideas.would those things affect the injectors firing anyway?

 

[4g63mightymax]

When I first put my 4g63 in my mightymax, I had the same problem and couldnt figure it out for the life of me.. Then one day after many weeks being baffled, I woke up at 6 am one morning, ran down to my truck in my PJ's, plugged the vacuum line into my MAS and it started right up first try. For some reason, that vacuum line needs to be plugged in (at least on my truck) for the injectors to fire on cold starts. Is your vacuum line plugged into your MAS?
Jeremy

True story, I swear........

 

[Number1gkid]

i was reading around online and i saw that there is an MPI Control Relay and i was wondering if that could have anything to do with my problem.i was wondering if anyone knew where this relay is on the car?

 

[4g63mightymax]

The MPI control relay, I believe, is the gold box next to the ECU. It has like 6 or 8 thick wires coming out of it. Is the vacuum line plugged in to your MAS yet? Because that will cause this exact problem.
just checkin
Jeremy

 

[Number1gkid]

if your talking about the plug that goes into the mas then yes its plugged inand im still gettin nuthin.and im gonna look at the MPI control relay right now.anymore help or idea will be much appreciated.

 

[4g63mightymax]

Im talking about the rubber vacuum line that goes to your MAS, not the wiring connector.....is that connected?
jeremy

 

[Number1gkid]

yea why wouldnt it be connected?isnt that part of the intake?

 

[zachab242]

that lil gold box i thought was the fuel pump relay??????
anyhow i have some pros with electrical and anyone know where this MPI conrol relay is??????????//

ZB