Is Stock (Old) Miata Fuel Pump Adequate?
 

The engine is running fine and currently the fuel system seems to be doing the job well. But I'm wondering if the old stock Miata fuel pump is adequate for the V8. There is no mention in Martin's guide about issues or concerns in this area so it must be OK.

Anyone have more insight with this? Should I worry?

When I get this thing tuned, the tuner will tell me for sure if it is running out of fuel supply so I'd rather correct it prior to that if necessary.

Mike.

Not sure on the Ford, but I'd venture a guess and say no. Personally, I'd throw in a 255/300lph unit to be on the safe side. LS swaps change fuel systems, ford is going to need slightly less, but much more than the original bp.

If the stock pump is working fine it will work fine with a V8. If its showing its age then swap it out for something better. I'm still running the stock 1994 pump on my 331 without issues. It has "only" 187k miles on it.

Keep in mind that if you do replace it with a Walbro or other after market pump its likely to be much louder and require an upgrade to heavier gauge wire.

-Jason

Jason thanks.

That is good to know and what I was hoping for.

I'm amazed at how small all the wires are on this Miata!

Mine just went but the car has over 234k miles so it was probably going anyway. Also, it pumped a whack load of dirt when the fuel sock broke.

Ive got about 800 miles on my swap and so far the pump is good, I dont know if its original to the car. works fine so far. I just wired a switch instead of a jumper so I can leave the key in run and not run the pump (for ecu programing and diagnostic stuff)

out of the megasquirt manual. for future reference


"4.2 Single Fuel pump
You will need a high pressure pump with enough volume at your operating pressure to feed you engine under maximum load. Typical pressures needed in the neighborhood of ~45 psi for port fuel injection, ~10-20 psi for TBI injection. A port injection pump will work with TBI, but not vice-versa.
A standard EFI install uses a single high pressure pump connected as per the diagram in 4.1 above. Depending on your target power output, many OEM style pumps may be suitable. Surprisingly, some of the Bosch inline EFI pumps installed on 100hp cars are actually rated to 450hp fuel capacity. OEM style pumps are a usually a good choice as they are designed for trouble free operation for tens of thousands of miles.
OEMs sometimes place the pump inside the fuel tank. In an EFI retrofit it is generally easier to use an external fuel pump.
If an OEM style pump does not offer sufficient output, there are plenty of aftermarket high volume EFI pumps on the market."

The stock Miata pump actually out flows a stock Mustang pump if I remember. It's one of those things that if it goes is worth maybe upgrading but not worth replacing if it's working fine on your donor.

We did replace one with a Walbro higher volume unit on one car. While the noise of the stock one is noticeable for only a few seconds the Walbro lets you know it's there all the time unless the top is down.

-Jason