Engine Performance This section is for discussion on all engine building related questions.
Sponsored by:
Sponsored by: KPower

Help! Car died. Fuel pump not priming. SOLVED: Main Relay

Thread Tools
 
Search this Thread
 
Old 03-24-2012 | 12:14 AM
  #1  
Doppelgänger's Avatar
Thread Starter
Elite Member
iTrader: (12)
 
Joined: Sep 2007
Posts: 6,850
Total Cats: 71
From: Charlotte, NC
Default Help! Car died. Fuel pump not priming. SOLVED: Main Relay

Ok so I'm stuck in the city. I pulled into a gas station to get something and when I got back in the car it won't fire. I can hear that the fuel system is not priming when I turn the key. Turns over fine but will not start. I checked the fuse and it's fine. What else can I look into that signals the fuel system to turn on? I'm running hydra 2.17 FWIW. There have been a few time in the past where when I am driving the Ecu seems to lose power for moment and the car fires right back up. Jeremy at FM said that some of the older hydras have a twitchy 5v power supply that can go bad. Id rather it not be that so I'm looking for some other things to check before takin the down time to send the ecu back to hydra for diagnostics.
Old 03-24-2012 | 12:45 AM
  #2  
Doppelgänger's Avatar
Thread Starter
Elite Member
iTrader: (12)
 
Joined: Sep 2007
Posts: 6,850
Total Cats: 71
From: Charlotte, NC
Default

Ok so I plugged the wirin harness back into the stock ecu and I'm still not getting fuel, don't know if that rules out the ecu or not :(
Old 03-24-2012 | 12:54 AM
  #3  
18psi's Avatar
VladiTuned
iTrader: (76)
 
Joined: Apr 2008
Posts: 35,821
Total Cats: 3,481
Default

I think it does
Old 03-24-2012 | 01:00 AM
  #4  
Doppelgänger's Avatar
Thread Starter
Elite Member
iTrader: (12)
 
Joined: Sep 2007
Posts: 6,850
Total Cats: 71
From: Charlotte, NC
Default

Something is blocking power to the ecu, the CEL doesn't light up when turning the ignition on
Old 03-24-2012 | 01:10 AM
  #5  
flounder's Avatar
Elite Member
 
Joined: Mar 2010
Posts: 1,524
Total Cats: 31
From: Detroit
Default

Bang on the top of the tank a few times. It's worth a shot.

eh...nevermind.
Old 03-24-2012 | 04:52 AM
  #6  
Reverant's Avatar
Elite Member
iTrader: (10)
 
Joined: Jun 2006
Posts: 5,991
Total Cats: 362
From: Athens, Greece
Default

Main relay is shot. Has happened to me 2 times so far. The CEL and battery light should light up when you switch the ignition on.
Old 03-24-2012 | 09:27 AM
  #7  
Doppelgänger's Avatar
Thread Starter
Elite Member
iTrader: (12)
 
Joined: Sep 2007
Posts: 6,850
Total Cats: 71
From: Charlotte, NC
Default

Rev- if you're right, I'll PP you $20 lol (seriously). I'm up for just a moment and will go down to the car in a bit. I had a hell of a night and took 2 Tylenol pm at like 3am....I'm going to sleep the rest of this off.

Where is the main relay again? Oh ---- why am I asking, I have sprinted FSM in the garage.
Old 03-24-2012 | 10:13 AM
  #8  
Reverant's Avatar
Elite Member
iTrader: (10)
 
Joined: Jun 2006
Posts: 5,991
Total Cats: 362
From: Athens, Greece
Default

Big green relay in the engine fuse box.
Old 03-24-2012 | 03:08 PM
  #9  
Doppelgänger's Avatar
Thread Starter
Elite Member
iTrader: (12)
 
Joined: Sep 2007
Posts: 6,850
Total Cats: 71
From: Charlotte, NC
Default

Car is alive. Thanks Rev. I honestly wouldn't expect that to shit the bed considering my luck with breaking things.
Old 03-26-2012 | 09:18 AM
  #10  
Reverant's Avatar
Elite Member
iTrader: (10)
 
Joined: Jun 2006
Posts: 5,991
Total Cats: 362
From: Athens, Greece
Default

I find it quite amusing that I went to my car today, only to have this problem...again. I'm going to swap that thing out for a solid state relay.
Old 03-26-2012 | 10:12 AM
  #11  
rleete's Avatar
Elite Member
iTrader: (21)
 
Joined: Jun 2007
Posts: 6,638
Total Cats: 1,284
From: Rochester, NY
Default

What would cause this? Why are you blowing so many?
Old 03-26-2012 | 10:24 AM
  #12  
Doppelgänger's Avatar
Thread Starter
Elite Member
iTrader: (12)
 
Joined: Sep 2007
Posts: 6,850
Total Cats: 71
From: Charlotte, NC
Default

I'm going to end up buying a spare one to keep in the car....Rev is going to make me paranoide with his third relay failure lol

The failure on mine was the pin that runs to the side that gets switched...it got so hot it turned the pin blue. Maybe the diode **** out? I understand how a relay works, but don't know how one side (don't know if it's main power coming in or going out) could get that hot without flipping a fuse.
Old 03-26-2012 | 10:29 AM
  #13  
Reverant's Avatar
Elite Member
iTrader: (10)
 
Joined: Jun 2006
Posts: 5,991
Total Cats: 362
From: Athens, Greece
Default

Apparently all NB2s do for some weird reason. Most likely the relay is underrated.
Old 03-26-2012 | 11:48 AM
  #14  
Doppelgänger's Avatar
Thread Starter
Elite Member
iTrader: (12)
 
Joined: Sep 2007
Posts: 6,850
Total Cats: 71
From: Charlotte, NC
Default

The B6S8 relay from the NA is a interchangable part. I wonder if its construction is any better since it is a different mfg.
Old 03-26-2012 | 11:53 AM
  #15  
Reverant's Avatar
Elite Member
iTrader: (10)
 
Joined: Jun 2006
Posts: 5,991
Total Cats: 362
From: Athens, Greece
Default

I'm thinking more like that the NB2 has more current passing through the relay. Not that the relay itself is bad. Just not capable for the amps that flow through it on the NB2.

Or it could be the specific make/model of the relay as you've said.
Old 03-26-2012 | 04:00 PM
  #16  
Doppelgänger's Avatar
Thread Starter
Elite Member
iTrader: (12)
 
Joined: Sep 2007
Posts: 6,850
Total Cats: 71
From: Charlotte, NC
Default

I'd be curious to hear other chime in of having relay issues as well...and if they are on the stock ecu or aftermarket.
Old 03-26-2012 | 04:02 PM
  #17  
Reverant's Avatar
Elite Member
iTrader: (10)
 
Joined: Jun 2006
Posts: 5,991
Total Cats: 362
From: Athens, Greece
Default

The first time around I was still on the stock ECU. I know at least 2-3 other cars that were on the stock ECU (but had band-AIDS on them, ie Powercards).
Old 03-26-2012 | 04:29 PM
  #18  
Doppelgänger's Avatar
Thread Starter
Elite Member
iTrader: (12)
 
Joined: Sep 2007
Posts: 6,850
Total Cats: 71
From: Charlotte, NC
Default

Interesting. This is my first dealings with having a main relay having issues.
Old 03-26-2012 | 10:46 PM
  #19  
codrus's Avatar
Elite Member
 
Joined: Mar 2007
Posts: 5,187
Total Cats: 859
From: Santa Clara, CA
Default

Keith Tanner had the main relay fail on his V8 Targa car during the event last year. In this post he seems to suggest that it's a not-infrequent failure on Miatas of all vintages:

http://www.flyinmiata.com/projects/t...ld.php?UID=212

--Ian
Old 03-26-2012 | 11:34 PM
  #20  
greeenteeee's Avatar
Junior Member
 
Joined: Aug 2009
Posts: 186
Total Cats: 3
Default

Originally Posted by Doppelgänger
I'd be curious to hear other chime in of having relay issues as well...and if they are on the stock ecu or aftermarket.
I'm going to look into solid state relays (noob w/ electronics). I've spares in the trunk now at all times though.

I actually haven't had one die on me (stock ECU everything), I thought it did though one time. Wasn't getting power to fuel pump, picked up a relay from Alex/2ndchanceroadster but while there, tested mine on his race car and it started up fine. Went back home and his relay worked on my car.

Days later, fuel pump dies, but wasn't the pump. The fuel pump assy wiring burnt a hole the ground wire to the FP, the plastic clip crumbled (literally) trying to pull it out. The positive wire was perfectly fine. As I said, I'm a noob w/ electronics but i'm guessing it has to do w/ the relay... maybe sennding too much power, overheating the ground wire? There's a burn mark on the plastic that the interior fuel tank wiring plugs into..



All times are GMT -4. The time now is 08:17 AM.