Mitsubishi 3000GT & Dodge Stealth Forum banner
1 - 18 of 18 Posts

·
Registered
Joined
·
11 Posts
Discussion Starter · #1 ·
I’m a new owner of a 97 3000gt SOHC. Won’t get into details about the prior hack that worked on it for me but when I got it home it was missing the ignition relay and had a scrap fuel pump. Replaced both and it ran fairly well. I took it down a couple of weeks ago to clean and rewire the fuel hat /hanger and now I have neither power to the fuel pump nor spark. I purchased a hot wire kit from 3sx and can get power to the pump if I jump it. I get power to the chassis side of the connector but not to the bulkhead side. I ran a compression test and have between 150-165 Psi in all cylinders so I’m pretty confident it’s not the timing belt. Is there one component failure that could be related to both? Any suggestions on where to look? Thanks in advance.
 

·
Registered
Joined
·
39 Posts
MFI relay also needs to be checked. Its behind the carpet on the center council on the passenger side.... My knowledge is based on VR-4, not sure if base is different.... Your positive Your not getting spark?

how did you jump your pump? do you have a black test port by the battery like the VR-4's do?.
 

·
Registered
Joined
·
11 Posts
Discussion Starter · #5 ·
Thanks. I was thinking about the MFI. That’s a good place to check but i didn’t know if that effected the spark as well. Yes I do have the test port. I used a spark plug tester and got no reading so I do believe there is no spark. How I jumped the fuel pump was I connected a jumper wire to the hot side of the battery wire and the other to the lead on the FP hanger (hat). I can hear it run and I’m gettin fuel to the rails. I cannot here the MFI click when I turn on the ignition but I could never hear it so I discounted that test. I’m sure there is a post on how to check that relay. Thanks again.
 

·
Senior **i.e. OLD** Member
Joined
·
16,067 Posts
 

·
Senior **i.e. OLD** Member
Joined
·
16,067 Posts
 

·
Registered
Joined
·
39 Posts
Have someone hold the wire on the positive when using the test port. If you hear the pump run. Try amd start the car while they are holding the wire in the test port. If the car starts. You have spark... I recently did this with mine. I had a bad realy with my hotwired pump. Fired right up when using the test port.
 

·
Registered
Joined
·
11 Posts
Discussion Starter · #11 ·
Well I attempted to check both the MFI and the pump using the test lead. Upon closer inspection, I apparently do not have a fuel pump lead, What I thought was the FP was the Tac which was a lead rapped in a blue band. there were no leads (only 2) with a blue/black wire. When I removed the carpet from the console, I found I have two 4 prong relays-3 COM prongs and 1 ON prong. Not being an electrical genius I left them as they are. What I did was make sure the black lead was not for the fuel pump and tested for voltage when cranking, which there was none. I then took the Hot Wire relay apart and made sure I was getting power to the hot wire, which I was. I then measured output voltage from the blue relay wire while I was cranking and there was no reading. This would lead me to believe that something is wrong with the hot wire relay, but again Im no electrician so if anyone can confirm or deny this would be true please let me know. Im also going to email 3sx for their opinion on the issue. What still puzzles me is that I have no spark. I checked that again today with my test light and there was nothing. If this would be connected somehow to the MFI , if someone has instructions on how to check the dual relay, id appreciate that as well. Sorry I took so long to respond-without getting into detail a family member needed my attention more than the Mits .thanks again. The assistance is greatly appreciated.
 

·
Registered
93 NA ATX 3000gt DOHC
Joined
·
4,175 Posts
Thanks. I was thinking about the MFI. That’s a good place to check but i didn’t know if that effected the spark as well. Yes I do have the test port. I used a spark plug tester and got no reading so I do believe there is no spark. ............................... I cannot here the MFI click when I turn on the ignition but I could never hear it so I discounted that test. ......................
Some of your statements are very confusing, like first part of above one. What test port did you use to check for spark with a spark plug tester?

Concerning second part of above statement, if power supply side of MFI relay doesn't close when key turned to ON position, you cannot have spark since power will not be sent to crank & cam sensors. If it can't be heard you at least need to check for power to and from that half of MFI relay when key is turned ON, discounting that test was completely wrong path to take.

......................... When I removed the carpet from the console, I found I have two 4 prong relays-3 COM prongs and 1 ON prong. Not being an electrical genius I left them as they are. What I did was make sure the black lead was not for the fuel pump and tested for voltage when cranking, which there was none. .....................................
The ’96 & up cars do appear to have two smaller individual MFI relay housings mounted side by side with individual 4 pin connectors, as opposed to the single larger housing and 8 pin connector. But they both function the same as half is for power delivery to some components for ignition etc. and the other half for fuel pump control.

But I don’t know what “3 COM prongs and 1 ON prong” means in your description, and on fuel pump half of relay I don’t see a solid Black wire in electrical prints. I can only see Black wire with white stripe (Black/white) supplying power to relay at 2 locations and Black wire with blue stripe (Black/blue) leaving relay going to the pump. There’s also a White/red wire from pump half the goes to ECU to control fuel pump.

Not knowing or having a diagram of 3SX hot wire kit or where that relay is mounted in wiring, it might completely bypass and not rely on pump half of MFI relay to work.:unsure:
 

·
Registered
Joined
·
11 Posts
Discussion Starter · #13 ·
Some of your statements are very confusing, like first part of above one. What test port did you use to check for spark with a spark plug tester?

Concerning second part of above statement, if power supply side of MFI relay doesn't close when key turned to ON position, you cannot have spark since power will not be sent to crank & cam sensors. If it can't be heard you at least need to check for power to and from that half of MFI relay when key is turned ON, discounting that test was completely wrong path to take.


The ’96 & up cars do appear to have two smaller individual MFI relay housings mounted side by side with individual 4 pin connectors, as opposed to the single larger housing and 8 pin connector. But they both function the same as half is for power delivery to some components for ignition etc. and the other half for fuel pump control.

But I don’t know what “3 COM prongs and 1 ON prong” means in your description, and on fuel pump half of relay I don’t see a solid Black wire in electrical prints. I can only see Black wire with white stripe (Black/white) supplying power to relay at 2 locations and Black wire with blue stripe (Black/blue) leaving relay going to the pump. There’s also a White/red wire from pump half the goes to ECU to control fuel pump.

Not knowing or having a diagram of 3SX hot wire kit or where that relay is mounted in wiring, it might completely bypass and not rely on pump half of MFI relay to work.:unsure:
Thanks for your answer. Yes my wife tells mei talk in circles-I think it comes from writing federal grants for forty years. Anyhow after some additional probing and testing I found I did not have a fuel pump test “lead” in the engine compartment. i also found that my Hotwire kit from 3SX was malfunctioning and they are sending me a new one. Thank you very much for clarifying the MFI. I will replace that part as well. Again I appreciate all the help and knowledge from those that responded.
 

·
Registered
93 NA ATX 3000gt DOHC
Joined
·
4,175 Posts
........................... Thank you very much for clarifying the MFI. I will replace that part as well. Again I appreciate all the help and knowledge from those that responded.
You welcome for clarification of MFI relay operation, but I would test it at it’s connector while still plugged in, using connector back-probing method before replacing it. There's always a chance power is not reaching the relay or ECU as not causing it to close, when key turned ON.

The power delivery half (guessing left half) should have 12v on Red wire with black stripe constantly. When ignition switch turned to ON position, you should then be able to read 12v on the solid Red wire which indicates that half of relay closed and it’s sending out the power needed for engine start on that solid Red wire.
 

·
Registered
93 NA ATX 3000gt DOHC
Joined
·
4,175 Posts
Thanks. I’ll give that a try. Currently out of town so it will be a few days until I try. Thanks again.
You could also do same back probing test of fuel pump side of MFI relay (guessing right side). With ignition switch turned to ON position, you should be able to read 12v on Black wire with white stripe and when turning ignition switch to START position you should see 12v being pasted to the Black wire with blue stripe which feeds power to the fuel pump.

This is normal factory operation, but depending on how and where the pump hot wire relay is installed/wired this could vary :unsure:.
 

·
Registered
Joined
·
11 Posts
Discussion Starter · #18 ·
Sometimes you really feel like a butt. The first answer to this post was to check the fuse, which I did. I followed everyone's suggestions-checked the wiring, relays, ground, etc. Didnt have power anywhere. I checked the fuse several times. It was good. I even checked ALL the fuses with a meter. So what was the issue? A blown fuse! I must have developed a short in the hanger connector at some point after the last time I checked the fuse box. Anyway I bypassed the connector, replaced the fuse and after about 15seconds of cranking, it fired right up. The only thing I can think of is originally I must have had a bad ground and when I fixed that, the fuse blew. I dont know but it now runs. THanks to all for their suggestions and patience.
 
1 - 18 of 18 Posts
Top