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Fuel pump relay clicking off - possible faulty ECU?


fuel
"Just to be pedantic!"


Galant VR-4 org Post #: 1001093 posted 06/23/11 12:15 AM     Remind Me!  Send Private Message   Edit Post      
Hey guys,

Am looking at picking up a 1991 Mitsubishi RVR S AWD 5spd (same as Expo/Summit) which has the DOHC 6 bolt 4G63 engine but the later 2G style AFM.

The engine will start (but idle a bit rough, though comes right when there are more revs), but the MPI relay will click itself off just seconds after the engine starts, causing the fuel pump to die and the engine subsequently stalls. I've taken the cover off the relay and if you hold down the tab against the contacts the engine stays running. It is only one of the two relays inside the main relay box that seems to click off right away. The current owner has swapped out the AFM and the idle stepper motor thinking they were the culprit, before focusing towards the clicking noise he could hear when the engine stalled. I did notice when I got someone to hold down the relay contacts and giving the engine a bit of a rev the check engine lamp came on, but I didn't have an LED on me I could use to check the fault codes stored.

The ECU is part number MD166265 which I believe is specific to the 91-92 6-bolt 2L DOHC RVRs, and I tried to use the MD311121 ECU from my '93 RVR Sports Gear which has the 7-bolt 4G63 but the ECU plugs were totally different. The '91 RVR S appears to have the same plug layout as the E33A/E39A 6G Galants but I am unsure how a 6G Galant DOHC ECU would work in it as the RVR uses the later 2G style AFM. I didn't get a chance to open up the existing ECU to check for leaky caps.

I'm just wondering what would cause the relay to click off just seconds after the engine is started - I'm guessing it is somehow ECU related but in my experience with the dud ECUs the problem is usually just no running full stop. I guess I will have to clear the ECU fault codes too to see what's up.

Any advice, thoughts and comments are welcome.

Thanks!



'91 E39A Galant VR-4 Evolution | '80 A164A Eterna GSR Turbo

-- Visit my JDM Galant VR-4 info & specifications site here! --

Posts: 2160 | From: Toronto, ON, Canada | Member Since: 02/23/09 | IP: (118.90.43.104) | Report this post to a Moderator

gramkrakr89
Now with Jelly next week is roasted marshmallows and hershey bars
689/1000


Galant VR-4 org Post #: 1001133 posted 06/23/11 07:53 AM     Remind Me!  Send Private Message   Edit Post      
I don't claim to be an expert, but I had the fuel pump chattering problem on my galant. at first it would just click off and back on really quickly (shutting off the fuel pump momentarily), then it started chattering like morse code... The ecu was the culprit, and sending it to a reputable shop solved everything.

Hope this helps

Posts: 308 | From: Cincinnati, OH | Member Since: 01/25/10 | IP: (174.255.69.123) | Report this post to a Moderator

fuel
"Just to be pedantic!"


Galant VR-4 org Post #: 1001220 posted 06/23/11 07:01 PM     Remind Me!  Send Private Message   Edit Post      
thanks for that! that gives me some relief! I hope I can fix this ECU with new caps and repair any tracks that I can see damaged. My prior experience with dud ECUs have well and truly been too late, they worked one minute and then completely dead the next!



'91 E39A Galant VR-4 Evolution | '80 A164A Eterna GSR Turbo

-- Visit my JDM Galant VR-4 info & specifications site here! --

Posts: 2160 | From: Toronto, ON, Canada | Member Since: 02/23/09 | IP: (118.90.43.104) | Report this post to a Moderator

jepherz Galant VR4.org Moderator
Too Clean
1881/2000
50/1000


Galant VR-4 org Post #: 1001256 posted 06/23/11 10:56 PM     Remind Me!  Send Private Message   Edit Post   
Yup, it's the ECU. It is clicking on when you crank because the fuel pump always time when ign. Is in start.



-Jeff
1881/2000
50/1000

Posts: 7872 | From: KC, Missouri | Member Since: 08/08/04 | IP: (108.119.219.175) | Report this post to a Moderator


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