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I replaced the fuel pump on my 1985 rx7 gsl-se (27K miles -original owner). The engine had been cutting out at 4K rpm. The new fuel pump
solved that problem. I received a lot of good advice from this forum to resolve the original problem. Now months later, the new fuel pump seems to have failed totally.
The replacement was a Delphi Automotive Fuel Pump - FD0030 from O'Reilly. It worked fine at first. Then it stopped pumping fuel after a few months.
Then I bought another one from Autozone. That one doesn't appear to pump from the beginning. You can hear it run, but no gas out of the exit port. (Should have know the box in came in was open)
To check, I took each pump out of the car and funneled gas into the inlets, applied 12V from the battery directly to the pump. The motors run, but no gas out of the exit port.
(Doing this with the original one: it was loud but did push gas out of the exit port). Unless I missing something, I think the test is a valid indicator.
From my research, someone in this forum said they were using the 12A pump on their 13B (1982 pump: https://mazdatrix.com/product/fuel-pump-rx7-79-82/) and it worked fine.
Apparently they were tired of the Chinese knock-offs failing on a regular basis. I was wondering if anyone else has experience with the 12A fuel pump on a 13B.
Or possibly can provide another recommendation. As you all know, the OEM pump is no longer available.
Thanks,
don
First off, that's not how you test for pressure or volume out of a fuel pump. You need the Fuel tank volume to provide a head of supply, and then measure the volume output at the Fuel rail to verify you're gettig enough of both pressure and volume to power the injectors. Secondly, the 12a cars are carbuerated which means their fuel pumps provide low pressure at about 4-6psi compared to your EFI Fuel Pump that puts out from 44-60psi for fuel injection to work properly.
That said, the Mazda EFI Fuel pumps have a ve4y good service record and many original pumps are still going strong at 150k-200k miles, and my own ws still running strong at 250k when I replaced it as PM. There are several fuel filters in line to the pump which should be checked for blockage - starting from the tank pickup, there's a fuel coarse filter sock over the end of the uptake pipe. After that is a plastic cone screen filter at the Fuel Pump inlet pipe, then the pump, then the high pressure Fuel Filter after the pump and located at the same location. These should be replaced somewhat regularly, especially if you're refueling from gas cans or other rusty sources. From there, the fuel lines carry fuel to the Fuel Rail, the injectors, and then a Fuel Pressure Regulator attached with a Pulsation Dampner to match the one on the Fuel Pump which prevents hydraulic shudder at certain RPM in the Fuel lines which affects fuel injector function.
In my experience, changing the big metal high pressure Fuel Filter back by the pump solves most restriction issues, as it's inlet screen can be clogged by even miniscule debris that managed to get through the Fuel Pump. Second likely source is the plastic cone filter in the rubber line that feeds the Fuel Pump, which can pick up larger debris or sometimes residue from the tank, and become clogged, restricting uptake flow. If the Fuel pickup volume is reduced at all, the pump will cavitate and you won't build pressure.
Do you have the FSM pages for testing the EFI Fuel system? It's not complicated, but covers the stepwise logic to track down problems. I don't trust aftermarket EFI Fuel Pumps, and believe several Rx-7 specialty shops still carry it at ~$340 or so, which is what I paid to Mazdatrix for the replacement Mazda part.
I do have the maintenance manual and have read the testing procedures
My immediate issue is that there is no fuel flow at all. So I tested the pumps externally by inputting a steady supply of fuel to the input port of the pump (gravity feed).
Only the original pump output any fuel upon application of 12V. I was only interested if I got any output at all. The two replacements did not output any fuel. So, I
was checking for gross output, not exact pressure. Do you think the test procedure was itself faulty and I am pursuing a "red herring."
PS: I have replaced the filter when I replaced the fuel pump the first time.
You mentioned your the replacement pump you got, can you give a little more info as where to purchase it? Regardless of the condition of my two replacement pumps,
(my research shows that the Chinese made versions seem to be problematic), I would rather have a more reliable version.
Thanks again for you review, I appreciate your expertise and time that you take to respond with a your analysis.
don
Yes, the way you're testing fuel pump operation is faulty and won't reliably tell you if the pump will work in the car. Though it's extra work to get under there and swap a pump (*esp. with fuel in the tank...), it's the only way to ensure that the pump has enough input volume to pump output the the correct pressure and that pressure can only be built against the restriction that the filters, lines, injectors, regulator, and return line can provide. Though the FSM says 44psi at idle and up to 60+psi at WOT, the volume of fuel seen by the injectors is still quite small flowing through the Fuel Rail, but the port of the Fuel Injector sprays regardless.
After a 5min search on Mazdatrix and RacingBeat, it appears that the 84-85 GSL-SE fuel pump is NLA. Looks like your only option will be to try your luck on the WTB board here and hope that another member has a known good pump, or you can research use of a quality aftermarket 2nd Gen Fuel Pump, which might work. All of the 2nd Gen cars were fuel injected, but with staged pairs with 4× injectors of lessor flow rating. I would probably go down that road vs. hoping to get lucky with a used OEM pump.
My advice, were it my car, would be to install the original OEM Fuel Pump and use the FSM test procedures to see if it's truly the pump failure. As with most motor driven pumps, they either work or they don't. You may find that a clogged Fuel Filter, inlet screen filter, or other obstruction has been cleared and you're back up and running with minimal hassle. What I've found over 40yrs of Rx-7 ownership is that these cars get a bad reputation by poor mechanics and tinkerers; they were built to be reliable and trouble-free as long as they were maintained appropriately. Your SE with 27k original miles was not maintained properly, because it sat dormant for too long, which is the worst thing for any car.
Case in point, my 84SE has 252k miles on it and gets driven biweekly, at a minimum during the summer, and almost daily during the nicer months.
I wanted to close out this thread. First thanks to LongDuck for his detailed responses. It is comforting to know that there is a "go-to expert" available. The dealers
around here do not seem to have first gen. RX7 expertise anymore (retired/left). So it is good to have a source when needed. I think I have maintained my RX7
adequately, although it only has 27K miles. I do drive it periodically in the summer, and in the winter (it is always in a heated garage) I start it periodically to keep the battery up
and keep the fluids flowing. Never had a problem until this.
I just installed the Walbro fuel pump (made in USA) I ordered. Got it direct from Walbro because it was cheaper that way. Amazon wanted about a $100 more, luckily I read the
reviews and someone suggested go direct to Walbro to get better pricing. They were excellent to deal with by the way. I tested the pump out of the car for gross operation and
it was fine. Installed it and the car is running great now. Good idle, pickup and top end.
Just wanted to complete this thread and share my experience, and possibly be helpful to anyone else.
Again, thanks,
don
Good choice on the pump (whichever one you chose). I'm a fan of flow-through fuel pumps as opposed to some of the older style with the motor on top and the pump mechanism below. Flow-through pumps are what OEMs use because they're typically much more reliable, compact, energy efficient, and can be used in-tank. The fuel flowing through the pump cools the motor, so it doesn't care if it's immersed in fuel or used externally.
I use OEM-style or OEM pumps whenever possible. Walbro and Bosch are both big suppliers to the auto industry, and with modern quality standards, automakers won't put up with failures.
Another option is a Bosch 69895 (0 580 464 206 in the Bosch catalog) -- it's available on Amazon for $140 -- 240LPH free flow.
A key thing to understand is that fuel pumps don't make pressure; they create flow (which is emphasized at the bottom of your chart). The fuel pressure regulator sets the pressure, so any pump designed for fuel injection will work in a carbureted application as long as you use an appropriate regulator with an adequate return system. The only reason you would be required to use a low PSI fuel pump is if you're running a returnless system, which I don't recommend for a variety of reasons.
I run Bosch pumps on both my RX-7s -- one injected, the other carbureted. Daily driven April thru October (to avoid winter road salt), reliable and quiet.
That's more flow than you need, but "better to have it and not need it than need it and not have it". As long as your fuel pressure regulator can bypass the extra fuel and maintain the pressure that your carburetor requires, you'll be golden.
Hey guys, i was driving my GSL-SE over the weekend and noticed it was cutting out around 4000-4200 RPM... and i figured that i should begin looking at the fuel pump / filters / etc...
i stumbled on this post last night hunting for fuel pump options... I've purchased Walbro fuel pumps from a small company called Auto Performance Engineering in the past for my GM small block EFI conversion... i discovered this company 10+ years ago on the thirdgen.org camaro forum, its a good company.
anyhow, they actually list the 84-85 RX7 1.3L installation kit that goes along with the GSL393 fuel pump.. i'm not associated with these folks whatsoever, but i have used them in the past with good experience. I hope you guys find it useful.
edit: i just bought mine and the install kit was $15, not $49, after going through the payment process ($130 total shipped).
xylorex: good stuff, I'm sure many people thank you for posting this. I wish I had found this info before. I ended up buying each fitting for the install kit separately after some research.
Thanks again, this is going in my RX7 file.
don
