Is changing fuel pump a noobie project?

[NP91NA]

Hi guys 91 miata full of gas’s was on a drive about 30 minutes and the car died no power at all and I am having it towed home. I think the problem is the fuel pump but I am worried about accessing it in the gas tank bc I’m not a pro. Is this a huge job?

[HarryB]

No, just a bit tedious. Disconnect the battery first. Need to remove the carpet behind the seats (on the parcel shelf), remove the access panel (a few bolts). Clean up the area over the fuel pump cover before removing it to avoid crap falling in your tank. Remove the fuel hoses and the connector, unbolt the panel, take it out carefully because the fuel sending unit might catch on it. Have a towel ready to not drip gas everywhere. It is worth replacing the in-tank fuel filter (get a genuine Mazda one) and the cover gasket as it will be perished by now. Fuel hoses may also crack during removal, so worth replacing those as well.

[— Agent☣Orange —]

I would test the circuit first. Make sure the pump is working (or not) with the ignition on and if not, I'd check the fuse and then power at the pump. If it does need replacement, I'd do what Harry says but I would also take out a seat, maybe both just to give myself room. That parcel shelf panel is held on by 300 bolts so if you have a cordless ratchet, you'd surely save your hands and a lot of time.

I think replacing a Miata fuel pump is very easy compared to other cars that have to go up on a lift, remove braces, exhaust and maybe a subframe just to drop the whole fuel tank before getting to the pump.

[HarryB]

Good tip on testing the circuit and if needed removing the seat, it is just 4 14mm head hex bolts. You do not need to remove the parcel shelf itself, there's a small access panel right above the fuel pump held on with 6 or 8 10mm hex bolts ;)

[— Agent☣Orange —]

Oh I forgot about that! It's been a while. Had to google a generic image.

Looks like 6 bolts
C51F4381-F30B-480E-8134-769658E01D0F.jpg

[★ revlimiter ★]

https://revlimiter.net/blog/2012/07/...-fumes-i-hope/

This post isn't about changing the fuel pump, but it does get you there. The panels removed to service the fuel valves are the same ones you need to pull off to get the pump out. Just gotta remove 6 more screws or so.


The fuel pump is the large item on the right with the hoses.

[— Phatmiata —]

dont forget to change the fuel filter (under the car) since you are doing fuel system work

[— kung fu jesus —]

+1 Test the circuits 1st.

Step 1: Park outside

Step 2: Locate and put a fire extinguisher nearby outside the car.

Step 3: Loosen gas cap to relieve the pressure in the tank. This prevents the golden shower.



After you remove the fuel pump hanger, lay something (non metallic) over the hole in the tank. This cuts down the fumes and prevents stuff from falling in while you change over the pump.

I have bought this for 3 separate Miatas. It’s a nice price, inclusive, and OEM brand:

https://a.co/d/6durlPJ

Every post above is very helpful.

Only other caveats:
Be gentle removing the fuel hanger assembly. The fuel level arm hangs out in space. Same with reinstalling it.

The two Phillips screws at the base plate under the pump are JIS and a little soft. I have used visegrips clamped to the head of the screw in coordination with a regular Phillips screwdriver just to crack them loose to remove them.

Check the wiring on the hanger (that goes in the tank) for shorts, burnt connections, etc. Check the connections at the top (outside the tank) for similar damage.

If your hanger is crusty and corroded, source another used one. SNS Parts can get you squared away (if in the US)

If you replace the pump and it doesn’t work, holler back. There will be a few steps to check where the fault is (pump relay or circuit controlling relay - they are different)

Take your time. Good luck!

[NP91NA]

Hi everyone I have replaced the fuel pump and the fuel pump relay and the car will not crank any other ideas? It seems that the engine is not getting fuel. Is there any other fuses I need to check?

[HarryB]

When turning the key to the "on" position, can you hear/feel the fuel pump priming?

[— kung fu jesus —]

By fuel pump relay, do you mean the one under the hood, or the big one up under the dash?

[NP91NA]

When I turn the key to on yes I hear the fuel pump priming and the relay I changed is under the dash, I didn’t know there was one under the hood. Where do I find the hood one passenger side?

[— kung fu jesus —]

If you hear it priming, it’s probs something else.

Can you describe how it died initially and what it is currently doing (crank, no fire etc)

[NP91NA]

Hi everyone about a month ago I was taking a Sunday drive in my Miata. After about 30 minutes the car died and I had to have it towed home. At home I replaced the fuel pump in the gas tank and the fuel pump relay under the steering column and the fuel filter under the car. The car will not crank. I feel like the problem is not fuel but fire or lack of. Any suggestions and where goes the fuel come into the engine under the hood? Is there another fuse I should check? What is the relay/fuse on the passenger side fuse box I have not changed that. Thank you

[— kung fu jesus —]

There is a big fuse on the right side fender fuse box.

If you are hearing the pump prime when you turn the key, something else is going on.

Fuel comes into the engine bay at the right side. You will see two hoses coming up from underneath. One is supply, the other is return. Make sure not to mix them if you remove both.

You need to check for spark.

It would not be uncommon for the cam angle sensor to fail at this age, and suddenly,
but that is only an idea.

Also, most importantly, did your timing belt break?