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Hello all,
I just want to post my experience, in case it helps someone else.
My RX7 is a 1985 GSL-SE.
After changing the oil, I tried to start the car, and it wouldn't start - couldn't hear the fuel pump kick on. (The oil change had nothing to do with this)
So my first move was to disconnect the fuel pump, in case the engine was flooded (pulled out the storage bin behind the driver's seat to unplug the fuel pump disconnect). That made no difference. Next, I jumped the pump, to bypass everything else, to make sure it worked, using a long wire with alligator clips to go from battery+ terminal to the blue wire w/brown stripe connection, then connect the ground connection to the chassis. Turned the ignition on, and the pump worked.
My next move was to check on the fuel pump relay, located under the passenger foot rest, next to the CPU. I unbolted it so I could shake it, hold it, feel it while I turned the ignition, and the engine turned over (got gas). My conclusion was that the relay got "stuck", and shaking it unstuck it.
Does anyone have experience with intermittent relays? I'm thinking that shaking it isn't a permanent solution...
I have had "weak" relays happen. I don't think they were "stuck". But we could just be describing the same issue with different terminology! Replacing them did the trick.
Did a search and found a relay that looks like a good replacement for $28 at https://www.densoproducts.com/denso-...avy-duty-relay
You can also look at mazdatrix for the same relay. It's listed as a 93-95 rx7 fuel pump relay for $73
Obviously it's your choice if you want to throw a replacement part at something that may or may not be bad!
Let us know what you decide and how things work out please!
Hi Ken,
Thanks for your reply. Have you done this replacement yourself?
The existing is a 5-pin Denso 056700-6380 relay. your link is to a 4-pin Denso 056700-6480 relay.
It requires a different socket connector. How did you handle that - just pulling out the existing ones and individually plugging them in?
And ... how does one decide which wire not to connect (going from 5-wires to a relay with only 4 wires?
Just looked at the schematics for the 85 gsl-se. Been a few years since I had a gsl-se. You are right, there are 5 connectors and you won't be able to use the one I suggested. Yours is a Circuit Opening Relay.
There is one available on Ebay. But now you're throwing a used part at a "possible" bad relay. And reading LongDucks post it's rare that it's bad.
The linked thread covers it. If yours is noticeably corroded, then it could go bad, but more than likely - and since the Circuit Opening Relay is inside the car, under a panel - it's probably a different connection somewhere in the engine bay that's shorting out this circuit and the Relay is acting as the ground for something else.
I spent àbout 5 months troubleshooting what appeared to be a bad Fuel Pump, bad Circuit Opening Relay, or a short circuit which was intermittent. Turned out to be a shorted wire at the BACV on the Dynamic Chamber that would short out, blow the fuse on that circuit, and the car would die.
A sticking relay can usually be diagnosed by waiting for it to receive power, close the electromagnetic coil, and then if you tap it with a screwdriver, you'll hear the 'click' that closes the connection. They're electro-mechanical switches, not magic. This one happens to compare 2 sources for powering it; on startup it uses the starter as the trigger, then after the engine is running, it uses the air door switch at the Air Flow Meter as the trigger.
Wow. Great information! Thanks guys!
LongDuck's explanation is a bit above my pay-grade, but what I get out of it is: "check elsewhere for a deteriorated wire."
What about removing the plastic housing from the relay to see if there is any corrosion on the contacts, then cleaning it, if needed?
To simplify the search for the next guy with this "challenge", here is LongDuck's message reposted below:
(Lead in: the relay for a 13B is under the passenger footrest. The relay for a 12A is under the dash, next to the steering column.) "Note, the FSM refers to this as the Circuit Opening Relay. It's located on the plate which holds the ECU in place at the passenger footwell, and is well marked. It's purpose is to provide 12v power to the fuel pump until it's told NOT to, hence the name. This diagram is straight out of the 84 FSM and is specific to GSL-SE:"
I believe there is a bypass pigtail that can jump the airflow meter, located under the hood next to the airflow meter, to be able to test if that meter is at fault. (I keep a U shaped piece of 12ga copper wire there for that purpose.
Follow up: I placed a call to Denso. They tracked down the Mazda part number, and they believe that a '90-'93 Miata Fuel Pump Relay (N236-18-821) will fit. It is also for the '92-'95 323 S.
As noted above, Atkins Rotary sells it for $84.
Mazdapartsconnect.com sells it for $79, listed for a '95 Mazda MPV
The following message thread had the issue as this one. They found that the "N236-18-821" doe not fit a '85 GSL-SE even though it looks identical, and "normally open": https://www.rx7club.com/1st-generati...ellow-1133639/
but found a "matching" Duralast relay - fuel pump 20190 for $80 that "doesn't fit" (picture below) https://www.autozone.com/fuel-delive...190/953659_0_0
And lastly, https://www.amayama.com/en/part/mazda/n23618821 has it for $52+$17 shipping (?direct from Japan??)
06-15-24, 05:50 PM
