OEM F/I fuel pump limit-replacement?

[F3BZ]

anybody maxing out or having starvation issues with the oem fuel pump on higher HP builds? what do you think the limit is of these pumps and is there a drop-in higher capacity unit available? i seem to recall mention of a Walbro pump for the RX-7 as a possibility. true?

[Dragonhealer]

The factory fuel pump will support 250whp for years. At 350whp there is no room for wear.
A Walbro 255 is a popular replacement, don't know if there is one that is an exact fit.

[F3BZ]

thanks. 250HP is well above my plans for an NA 1.8 build.

[Dragonhealer]

EFI fuel pumps are usually rejected based on amperes draw being too high, but a stall test is easy to do.
A new pump should develop 90+psi when stalled, at 75psi stall replace the pump.
Some have related original pumps having a lower pressure relief valve, this could be true but I have not seen that yet. I have seen that on a few cheap after market pumps.
Dont be fooled by price however, I found pumps on Rockauto made by an OEM supplier in Korea for $10, two pumps in service and they test and perform perfectly!

[F3BZ]

by "stall" do you mean the pump stops at that psi or blow a fuse or just will not put out any higher than 90? too late for the rockauto tip. i just bought one off the bay for a backup. they don't come up too often, aren't available from ford and the aftermarket ones don't look like a drop in. the OEM ford part is a Denso made in japan. a lot of parts were sourced from japan even though the car was built in korea

[w4rkry]

by "stall" do you mean the pump stops at that psi or blow a fuse or just will not put out any higher than 90? too late for the rockauto tip. i just bought one off the bay for a backup. they don't come up too often, aren't available from ford and the aftermarket ones don't look like a drop in. the OEM ford part is a Denso made in japan. a lot of parts were sourced from japan even though the car was built in korea

All the aftermarket ones I have ever seen are direct drop in, and Brand new Denso units are pretty easy to find on ebay for the $108 zone, just not with a Ford/Mazda part number, as it was shared by many JDM cars of the era.

[Dragonhealer]

T in your 100psi fuel gauge in the hose to the fuel rail, start the car (or jumper the fuel pump on), briefly pinch off the return line while watching the guage, this reading is stall pressure.

[F3BZ]

thanks. good info