NA Miata fuel pump diagnosis, removal and replacement

How to diagnose, remove, and replace a bad fuel pump.
Vehicle: 1992 NA6 Miata

[@pawpatina]

just shows how reliable these cars are. and easy/cheap to fix. I have never had a pump go bad... and that gas cap needs replaced.

[@Thee_muffin_man]

Thanks for this video... just did exactly as you did and perfect.

[@blue_miata]

Thank you! I’ll be adding some new videos soon from this car’s turbo build, stay tuned! \m/(>

[@alexmessina3383]

Nice vid Blue Miata. thanks! Small point. Grounding the Fuel Pump from the Diag Connector does not "by pass" the relay. Rather it directly ground the relay control side, activating the main pwr feed through the relay. That is, you do the grounding manually, taking over the job that the ECU does when you turn the key to start and it receives a crank signal.If it doesnt work, it means the FP is bad or the FP power feed is bad. If it does work, and the pump wasnt working previously, it means the ECU is not grounding the pump, or the ground wire controlled by the ECU is open. ;-) Neither means that the relay is bad, in which case the FP wouldn't work when you ground it manually or when you go to Start. You have to test the relay separately

[@auxpower13]

Great video, dude. My favorite part is your smile at the end.

[@blue_miata]

Appreciate it! Thank you for watching! 😊👍🏻

[@VINZBROWN]

Ive been watching alottta of these. I got alot outta your video. APPPREECH!

[@lanakrawczel8557]

Very good demo, and the comments were good also. This video and the comments cover a lot of ground, and give good insight. Thanks, FK

[@flyingfish2]

Good video man, I have same year , will follow your advice and of course release the fuel cap.lol

[@CloroxBleach-qu4pp]

Thank you for this video really enjoyed it !!

[@jonolam101]

So what would be the next thing to check if the fuel pump primes after jumping the pins? My 93 currently keeps blowing the 30A INJ fuse every time I crank the vehicle, hope to get some insight

[@blue_miata]

jonolam101 I’ve never run into that before. The first thing I would check would be the ignition coil, to see if it’s arcing to the frame. I changed mine out about a year and a half ago because it was really corroded and causing an intermittent misfire under hard acceleration. If that turns out to be fine, I’m afraid it’s a case of following all the wiring from the fuel pump to the injectors and checking for wear and shorts. I hope you get it all sorted and back on the road soon, best of luck 🍀 and thank you for watching!

[@aaliyahfolco5733]

So when I go to start my Miata it cranks but won’t start. The fuel won’t start when the car is in accessory mood. But it worked when I rigged up the yellow box under the wheel to the pump. And when I crank is my car smells like gas. So I don’t know would that be a bad fuel pump.

[@blue_miata]

I’m not sure exactly what the problem is from your description, but it sounds more like you may have a tiny leak in one of the rubber fuel feed lines to me. Thanks for watching! I hope you get it tracked down.

[@SkylerB17]

im replacing my fuel pump and filter as preventative maintenance, because i can almost guarantee theyre original from 1990. could be wrong, but im doing it anyway. but my rear window leaks and im terrified to see the potential rust underneath the rear carpet. any recommendation on fuel pump? ive heard the Chinese Denso pumps fail rather quickly, and an OEM mazda one is like $400, which is insane. not sure what to do about that.

[@blue_miata]

The one I installed in this video is a denso, and it’s still going strong 3+ years later. If you’ve got the budget and want to install oem, I would say go for it, but the less expensive option has worked out well for me. Thank you for watching! Best of luck with your Miata! 😊👍🏻

[@SkylerB17]

@@blue_miata ok well thats good news. I was also thinking of going with an aftermarket Deatschwerks pump for about $100. Full kit comes with gaskets and a new sock as well. But I've heard mixed things about them as well 🙄 lol who knows. Mine hasn't failed so I have time to decide. Thanks for the good video!

[@ralestrom2369]

I have a ‘97 and I don’t have the area for the jump wire. Is it not there or somewhere else?

[@blue_miata]

Thank you for watching! I believe the 97 has the 1.8 motor. I’m not as familiar with their setup as far as wiring and diagnostic. I believe that they are OBD-2, which means that you should have a diagnostic port located somewhere under your steering column. An OBD-2 scanner will be able to diagnose whether it’s your fuel pump giving you trouble. You should also check Miata.net as they have very comprehensive forums on all models and motor specs, and they are easily searchable. Chances are that someone has already posted exactly how to fix it. Best of luck! ✌🏻

[@cameronhall6623]

what made you think your fuel pump went out ?

[@Sertao2013]

At :50 you said it will send power directly to the fuel pump . Thats not true . Its sending power to the relay . If you listen under the dash as you touch the wire with the paper clip you should hear a clicking noise . That clicking noise is the relay clicking on and when you disconnect the the wire you will hear it click again . Just because you hear the relay clicking doesn't always mean its working and sending power to the fuel pump . Its just means its clicking . At 3:26 when you disconnected the electrical wire connection at the fuel pump you didn't even check to see if you were getting power to the pump you just started taking it apart . You should have checked for power getting to the pump first while the relay is still clicked on . If your not getting 12 volts to the pump then the relay is bad and is doing nothing when you hear it clicking . If you are getting power at the connection then take out the pump . Another thing you didn't do was to put 12 volts to the pump once you had it out . You should have put 12 volts to the pump to see if it pump turns on or not . There is a wire set that goes from the top of the housing to the pump itself any of those wire could have lost connection . You could have did all that and it be a bad wire in that short wire connection . You also should have plugged in the fuel pump before you put it into the gas and turned on the key with the relay wire off . Why would you drop the pump down in the gas a put it all back together before you checked to make sure it was getting power and running ? If anyone is doing this put a tester to the wires at the fuel pump connect to make sure your getting power to the pump if your getting power to the pump and you still don't hear the pump once you take the pump out test to make sure your getting power to the pump itself at the lower end of the short wire connection . If your getting power to the bottom of the connection put 12 volts to the pump motor and make sure the pump doesn't work before you go buying a new pump .

[@ODSoldier]

You are so correct my friend

[@ByLionZ]

I don’t hear the pump with the diag box terminals jumped, and i replaced the pump with no success. What should i check next? Crank no start

[@blue_miata]

If it will still crank but not start, try opening the oil filler cap and looking at the cams while someone else cranks it. If you don’t see them moving, then your timing belt is broken. I’ve had that happen before too. Best of luck! Thank you for watching! ✌🏻

[@ByLionZ]

@@blue_miata Timings all good. The no success part was referring to not hearing the pump after swapping it, still makes no noise even jumping it through diag box

[@blue_miata]

@@ByLionZ Hmmm… I’m at a bit of a loss. Possibly a bad fuel pump connector? Or (I hope not) a worn or cut wire? I’m sorry I can’t be more help, but without being able to get my hands on it that’s my best guess. Miata.net forum has a great resource thread that may be helpful. forum.miata.net/vb/showthread.php?t=279746

[@ByLionZ]

@@blue_miata It was the connector inside the basket, badly burnt

[@michaelchu1602]

Is it safe to use the diagnostic fuel pump by pass to turn on the car to verify fuel pump relay is fine?

[@blue_miata]

Michael Chu Yes. It’s safe. Thank you for watching! ✌🏻

[@elkameno1959]

I'm in the process of replacing mine in my 2000 - what a pain to this point to determine the problem.

[@blue_miata]

elkameno1959 indeed! The no-start diagnosis protocol on Miata.net forum is a good reference, as well. Good luck 🍀 thank you for watching!

[@thehang3r795]

What fuel pump brand did you get?

[@blue_miata]

The brand was Master Pro. Easy to find on eBay, not expensive at all, and has worked great ever since. 👍🏻 Thank you for watching! 🙏🏻

[@OKCStinger]

Been troubleshooting my Miata for a good while and your paperclip trick worked and pinpinted what was my issue

[@blue_miata]

Myles M awesome! I’m glad I could help! Thank you for watching 🙏🏻

[@anandsharma8234]

It was kind of hard to focus with the music but thank you!

[@Backyard_customs]

Is did help me out but when removing the pump you don’t show and mine is stuck

[@6mtcruiser]

After jumping the fuel pump and ground pins and bypassing the fuel pump relay, I can hear the fuel pump. So I replaced the relay and fuel pump is still not working. I bypassed it again by jumping it and I can still hear the fuel pump. Anything else it could be?

[@blue_miata]

Affan Kaji Have you checked the timing belt yet? If you remove the oil filler cap and look into the valve cover and have someone else crank the car, you should see the cam turning. If it’s not, then the timing belt is broken. Another possibility is the ignition coil. You can get a spark tester for $5 or so at any auto parts store. Hope this helps! Best of luck! Thank you for watching! ✌🏻💙😃

[@elkameno1959]

what does the fuel pump sound like?

[@nicholassoto1039]

Did you ever figure out what was wrong with your Miata Affan?

[@eduardoaguilar3675]

@@elkameno1959 it goes.....zzzzzzeeeeeeeeee.....like that

[@migueld4364]

hey hey - whats that lightly rusted metal sheeting called? mine was rusted beyond belief so i need to replace it, but im not sure what to look up.

[@blue_miata]

Miguel l3rightside I think the one that protects the whole assembly is called the fuel pump cover plate, but I’m not 100% certain that’s the proper name. The part that bolts into the tank is the fuel pump assembly. I hope that helps, and best of luck to you! Thank you for watching! 😄👍🏻

[@elkameno1959]

on my 2000 I just remove the rust and sprayed it with some paint-

[@jaybyrd5556]

Where did you find your fuel pump?

[@blue_miata]

Jason Rivera I picked it up at O’reiley auto parts. They carry a lot of miata-specific parts. Thank you for watching, and good luck! 🍀

[@funkdiggler6768]

What are u suppose to hear if the fuel pump works?

[@blue_miata]

Angel A It will be audible when you turn the key as a soft buzzing or whirring from the center of the shelf behind the seats. Thank you for looking!

[@nicholassoto1039]

@@blue_miata if I do this method and I find that it's my fuel pump relay and not the fuel pump itself will I be able to start the car or will I need to replace the really first?

[@blue_miata]

nicholas soto you will need to replace the relay. I don’t think it’s safe to operate with the relay bypassed. *However* in theory it should turn over.

[@jakeguitarbass7209]

Nice video! How come there’s a lot of rust on the fuel pump cradle stems?

[@blue_miata]

MollyTheMX5 the previous owner left it sitting for quite some time; I just haven’t gotten around to removing it. It’s not getting into the fuel so I’m not in a huge rush. There’s a couple other projects in line ahead of that one, anyway! 😂

[@jakeguitarbass7209]

Blue Miata That’s good man. I also recently changed my fuel pump on my NB. But I noticed a tiny little bit of rust hanging around the edges of the surface when you pull the cradle out. I guess it will never be a problem? As long as it seals...

[@iamharbo]

I hear the fuel pump and I changed the relay and it still won’t run

[@edwardhalpin7503]

Check for spark, you may need to replace ignition coils. Pop the oil fill cover off to observe camshaft rotating. (This verifies the timing belt is intact, [fingers crossed]) measure fuel pressure, you filter may be clogged

[@jaydinelkins5206]

You call its a fuel filter the entire video😂

[@blue_miata]

I know!😂 I thought about going in and doing a super obvious overdub, but I figured most folks would get it. 😂 Thanks for watching! 👍🏻

[@elkameno1959]

see my video I uploaded today - I found my problem !!! what a problem to have .