Lightsaber

Attachment 326619





My 2014 Evo X GSR has been having problems recently that it sometimes cranks but won't start. It happens in hot weather, especially when the engine bay is hot. Even when it starts, it often struggles at first to reach idle RPM.

The stock fuel pump relay (M) has endured 29,600 miles, so it's the usual suspect. I have taken several relays off for the salt shaker test. All other relays are quiet, but the fuel pump relay (M) indeed has something loose inside and sounds like a salt shaker (). Interesting enough, however, when I removed the fuel pump relay (M), the car starts right up. Not sure why, but maybe the relay actually restricts the fuel pump, instead of enabling the fuel pump? Anyway, I have temporarily switched the location of high beam relay (G) and fuel pump relay (M) as a quick and dirty fix.

So here are my questions:

1. Can I actually drive without the fuel pump relay (M), i.e. with slot (M) empty? Could it damage or wear out the fuel pump? lol...

2. I'm planning on buying a couple of replacement relays, one will replace the bad one, another one as a backup just in case. Can I put the back-up relay in slot (F), which is for the headlight washer (I think it could be legally required in some markets. USDM Evo's come from the factory with this slot empty)? Could the relay be damaged in this slot?

Thanks in advance!!!



P.S. I've also done a few other tests:
Removed relay (N) - Car won't crank, leading me to believe that this is probably the starter motor relay.
Removed relay (G) - Low beam works, but I cannot turn on high bream anymore. It stays at low beam.
Put a non-salt-shaker relay in slot (M) - Car starts right up.
Put a salt-shaker relay in slot (M) - Car cranks but won't start mostly. Sometimes it might start after many tries. Even when it starts, the engine struggles to reach idle RPM. Experiences power loss when driving.
Leave slot (M) empty - Car starts right up. This is most confusing part for me. Not sure if sorcery or a program glitch in the Matrix.

Well, unfortunately we can say now that the new Panasonic relays (part number 8627A030) are not really bulletproof like many, including me, have previously speculated. It lasted 2 years or around 30,000 miles for me. I don't know how the new grey MFI relay (part number MR400709) keeps up at this point, as mine (knock on wood) hasn't gone south for now.

As Mike W at Road Race Engineering reported back in 2011, the fuel pump relay on our cars simply deteriorates prematurally:


^At barely 4,000 miles


^First sign going bad


^Worn, but still working


^He's dead, Jim!

(Source: https://www.evolutionm.net/forums/ev...open-pics.html)

^As deanob posted, Mitsubishi service bulletin recommends replacing old black relay MR588567 or green replay 8627A011 with the blue relay 8627A024, as well as replacing the old black multiport fuel injection (MFI) relay with the grey MFI relay MR400709 (comes stock with 2014+ model year Evo's).

I'm now wondering whether the blue relay 8627A024 (recommended by the bulletin) or the new Panasonic black relay 8627A030 is the better choice. The Panasonic black lasted only ~30,000 miles for me.

At last, here is what 98930EVO has recently summarized.

moparfan

I have no idea, but thanks for your work here. Where did you order your relays from?

It seems like the choice now is MR122409 (updated OMRON black) or Panasonic Orange/Yellow . The Large grey MR400709 stays the same.

Lightsaber

I ordered the new relays from AMS Performance in West Chicago.

My educated guess is that 8627A024, 8627A030, and 8627A049 are all viable relays for the Evo. I think their lifespans in the fuel pump relay slot are supposed to be the same: around 30,000 miles. I also think that the problem is simply that an engineering college intern at Mitsu chose the wrong socket size for the fuel pump relay, which goes through so many cycles and he or she should have given it a much bigger socket to receive a much more durable relay. I also had an interesting conversation with the top dog at the dealer's service department. He told me even the updated relays at the fuel pump slot should be changed every 50,000 km (~30,000 miles), regardless of symptoms. It's simply not worth it to wait for it to break.

All post-recall or post-2014-model-year relays, when not in the fuel pump slot, are perfectly fine, because they simply don't go through that many cycles.

Even the older relays might be just okay in all the other slots. In the fuel pump slot, they could fail very quickly and it's indeed wise to replace them with a newer one ASAP.

Speaking of why I can start my car with the fuel pump slot empty, I have no idea, but I speculate it does make the engine run lean under boost, just like having a bad relay there. Therefore, I have been running with a good relay (taken from high beam slot) in that slot and I advise you and everyone not to adventure with an empty fuel pump slot.

In the long run, the wideband god might be our only salvation:



Also, here is an earlier bulletin issued by Mitsubishi in January, 2010:

Lightsaber

Update:

Hooray! My AMS fuel pump relays have arrived! They turn out to be 8627A049 orange relays! Very awesome!!!

Dross99_si

Oh ****, orange now???

moparfan

Tall black relay is fine. Tall orange sealed relay is better.

Lightsaber

That's what I speculated too. Taller relay=more bread in it to last!

oblivionis

Looks like the answer was in your own post:

Since this relay controls the high-low voltage crossover of the fuel pump, having it go bad can cause the fuel pump to only run at low voltage instead of +12 V at WOT.


This is a very informative thread so I'm just bumping it up.

2006EvoIXer

iTrader: (1)

Interesting. Has anyone tried installing a diode/capacitor to reduce/eliminate the sparking when relay switches on and off?