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No injector pulse or power

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Slo2gn

Proven Member
68
6
Apr 27, 2014
Honolulu, Hawaii
I have a 97 GST with a Non Eprom ECU I tried swapping a Eprom and socketed Ecu in did the plug swap with no success The car would just turn over but not fire so i swapped back in the non eprom ecu and still having the same issue.. so I ran down a to do list of no start condition.

Initially I ruled out fuel because the Afpr was reading fuel pressure on the return side.. checked spark and that was very good.. so then I had a friend crank over the car and it was reading almost 70 psi on cranking which was wierd because I set the AFPR and never had any fuel pressure issues in the past.. after a second look I pulled the fuel rail and had a friend crank and no fuel came out of the injectors then I ran a test light to all the injector pigtails and, there was no power to all 4 injectors..

I did some searching on here and google and came back with MPI relay or the ecu has an issue.. Can some guide me in the right direction of how to test the relay to see if they are working properly? also a picture below of what MPI relays my car is equipped with
 

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There are several tests, the easiest is does the CEL/MIL turn on for 5 seconds when you switch on the ignition? If it does then the MPI relay is working.

Next would be to measure the voltages at the pins of the relay.
As you noted there are actually two identical relays on that bracket on the 97. One is the MPI relay and the other the fuel pump relay. The relay pins are:

Pin 1 Normally Open Contact
Pin 2 Relay Coil
Pin 3 Contact Common
Pin 4 Relay Coil

The MPI relay gets power from the #4 20A fusible link marked Engine.
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At the MPI relay that is the Red/Black wire that runs to pins 3 (contact) and 4 (coil). You should measure battery voltage on both all the time.
The output of the relay contacts is the red wire on pin 1 which feeds the ECU and engine MPI circuit. It should measure 0v until the ignition is turned on.
The Blue/Green wire on pin 2 runs to ECU pin 38 and when pulled to ground by the ECU activates the relay. You should see battery voltage on it until the ignition switch is on at which point it should go low and pin 1 should go to battery voltage.

You can test just the relay by applying 12v across pin 2 and 4 and making sure that pin 1 and 3 have continuity between them. When the voltage is removed there should be an open between 1 and 3. I forget offhand what the coil resistance is but it should be around 120+ ohms between pins 2 and 3.
 
Check all your fuses, crank sensor, fuel pump. Keep us posted about what happens. Your obviously getting no power to fuel pump or injectors so if its not the mpi relay id check what i suggested..
 
Check all your fuses, crank sensor, fuel pump. Keep us posted about what happens. Your obviously getting no power to fuel pump or injectors so if its not the mpi relay id check what i suggested..
I am getting fuel pressure that means the pump is working
 
Well you said you had a friend crank it and no fuel came out so how did you get fuel pressure with no fuel. You mean just air pressure or what? That is confusing me.
 
I have a AFPR Read the second paragraph on my original post.. in order to achieve proper fuel pressure with a AFPR you need a fuel pressure gauge to set the pressure correctly.... so that is how I know that I am getting fuel pressure
 
Well you said you had a friend crank it and no fuel came out so how did you get fuel pressure with no fuel. You mean just air pressure or what? That is confusing me.
You need to read the Original post the only thing that confuses people is that people like you are clearly not reading the post correctly I am going down the list that Steve posted because its logical.. Fuel was in the fuel rail after I pulled a injector and ran power to it via 2 jumper wires it was working then after that I installed the injector back on the rail with the rail off the manifold i had a friend crank and there is no injector pulse no fuel coming out of the injectors and fuel is passing through the rail because I emptied the rail by pulling a injector and also the regulator is showing fuel pressure during cranking
if you would like I will gladly post a video for you
 
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You need to read the Original post the only thing that confuses people is that people like you are clearly not reading the post correctly I am going down the list that Steve posted because its logical.. Fuel was in the fuel rail after I pulled a injector and ran power to it via 2 jumper wires it was working then after that I installed the injector back on the rail with the rail off the manifold i had a friend crank and there is no injector pulse no fuel coming out of the injectors and fuel is passing through the rail because I emptied the rail by pulling a injector and also the regulator is showing fuel pressure during cranking
if you would like I will gladly post a video for you
Like i said its your crank sensor. And dont care much for your sarcasm either. Dont burn your bridges. Your welcome. Now go change your crank sensor, and hit me back.
 
Sorry Jim but I agree with the OP. he wasn't sarcastic in my opinion and the post was clear to me. I think it could be crank sensor also. OP why don't you try adding a little starter fluid manually just to make sure it runs.
 
Sorry Jim but I agree with the OP. he wasn't sarcastic in my opinion and the post was clear to me. I think it could be crank sensor also. OP why don't you try adding a little starter fluid manually just to make sure it runs.
I dont like being thrown in or grouped with others. Dont care for the term people like you. Nobody is like me but my kids. Just my personal views, regardless im positive its the crank sensor.
 
I dont like being thrown in or grouped with others. Dont care for the term people like you. Nobody is like me but my kids. Just my personal views, regardless im positive its the crank sensor.
Jim sorry for the sarcasm but you were LOL'ing air pressure.. so I took that as Sarcasm no disrespect intended..However I know for a fact it is not my crank sensor.. because the car tried to start when I pulled the rail and 1 injector fuel leaked into the bowels and the car fired for a brief second.. because compression was lost due to the injectors not being seated it would not run FACT the Motor is not getting fuel and the crank sensor is fine so is the cam sensor FACT the injectors have no power I did a test light on the pigtails and they have ZERO power... Fact there is Fuel pressure and verified that by pulling the return -an line off to make sure


I am pretty sure I am not burning my bridges and, I was only reiterating what was stated in the second paragraph I tried to be as clear as possible to eliminate confusion.
 
I will post results tomarrow I am going to run down the list of to do's including starter fluid
 
Jim sorry for the sarcasm but you were LOL'ing air pressure.. so I took that as Sarcasm no disrespect intended..However I know for a fact it is not my crank sensor.. because the car tried to start when I pulled the rail and 1 injector fuel leaked into the bowels and the car fired for a brief second.. because compression was lost due to the injectors not being seated it would not run FACT the Motor is not getting fuel and the crank sensor is fine so is the cam sensor FACT the injectors have no power I did a test light on the pigtails and they have ZERO power... Fact there is Fuel pressure and verified that by pulling the return -an line off to make sure


I am pretty sure I am not burning my bridges and, I was only reiterating what was stated in the second paragraph I tried to be as clear as possible to eliminate confusion.

Somebody will have to verify does crank sensor feed ecu to fire injectors. Leaking fuel and it fired does not rule this out. It did exactly what i suggested with starter fluid.
 
Quick update I had a starter take a dump on me I did add ether to the cylinders and it fired up.. momentarily... I am doing a few of the tests that were stated in the post if all fails Ill try replacing the the Crank postion sensor not to sound cheap but, I dont wanna be quick to replace it because I live in Hawaii and parts from oriley or Napa are marked up here because of the cost of getting parts to the island
Ill post more later
 
Reviving the thread so over a month has gone by i havent had a ton of time but recently I got back into the diagnosis.. I did the quick MPI relay test as far as the check engine light and it checked out and the fuel pump is pumping fuel.. I went and swapped known good MPI relay's into the car with no luck swapped known good injector resistor box and also swapped in different injectors with zero luck the car turns over if i spray starter fluid the car will fire momentarly until the fluid is burnt off.. could this all be related to a bad ECU? Could this all be a bad crank angle sensor?

Please help THANKS!!!
 
Hmmm. Glad you have it somewhat narrowed down. I had two friends in last month had their crank sensors go bad and it was just like what you were talkin about earlier.


I pretty much did everything on the list and Finally bought a new crank sensor and that did not work just turns over the only other thing I can think of is the Cam Sensor..
 
I pretty much did everything on the list and Finally bought a new crank sensor and that did not work just turns over the only other thing I can think of is the Cam Sensor..
Did you ever get the problem fixed? I've been dealing with it for a month now. My mpi relay will click sometimes. I'm thinking it's the cam angle sensor for the injector part they won't spray
 
Did you ever get the problem fixed? I've been dealing with it for a month now. My mpi relay will click sometimes. I'm thinking it's the cam angle sensor for the injector part they won't spray
Yes I did finally find the issue I am happy to report I cranked the car over long enough for the the ecu to spit a cel and it was a injector circut malfunction so instead of chasing a short in the entire injector circut I swapped in a rharness i sourced locally and car fired up!! pm me if you need help it is hard to get through but can be done
 
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