2.2E MFI Pump on 2.4E Engine?
 

Hi. I just bought a 2.2E MFI mechanical fuel pump for my 2.4 engine and my mechanic told me it won't work. I had not considered this at all, but it seems these pumps are "mapped" differently depending on engine size and the 2.2E pump would not provide enough fuel to my 2.4 engine. Does anyone have any experience with this and/or know if this is true? Any advice would be highly appreciated. Thanks.

Good question.

Yes, the 2.2 911E pump will work on your 2.4 911E engine. It can supply more than enough fuel. In fact it will work well to 2.8 and possibly larger. The difference between 2.2 (2195 cc) and 2.4 (2341 cc) is less than 7%.

That said, the 2.4 pump has a larger ‘space cam. This allows slightly more precise metering.

The critical issue is: How good is the 2.2 MFI pump? Was it running exactly correctly when last used? How long has it been out of service? What precautions were used to preserve its condition?

Short of having it properly rebuilt, I would find a perfect running 2.2E and temporarily swap pumps. This way you can confirm proper operation and the 2.2E owner gets an extended CMA. Your 2.4E can then get a known-good pump and you spend your CMA effort on other issues.

If you have the mixture correct on a 2.2E, you can best change the mixture for your 2.4E by the shims under the aneroid. This keeps your main and idle mixture adjustments mid-range. You are simply fooling it into ‘thinking’ it is at lower altitude.

Best,
Grady

Whew!
 

What a relief! Thanks, Grady. The 2.2E pump is freshly rebuilt, so it should be matter of setting it up and that's it. I have a couple of questions for you, though. First, what is the best way to prepare a pump for long-term storage? What must one do to assure an MFI pump will be preserved properly? Second, what is an "aneroid"? Thanks!

Take Grady advice (as always) by using a shim under the barometric cylinder on the top. This is exactly how I changed my 2.4E pump to work on a 2.7.
There are also other adjustments which could be made internal to the pump, but the above is the easiest.
Ed

Thanks. So, is "aneroid" the barometric cylinder on top? What exactly does it mean to put shims underneath? Does that mean I should put a wassher in? How thick? Finally, what is the best way to prepare a pump for long-term storage? What must one do to assure an MFI pump will be preserved properly? Thanks.

I have heard of filling it with Marvel Mystery Oil for starters...

At risk of hijacking, I had to bump this, as I'm facing similar issues with my 2.2E pump on my 2.5E/S motor. The shim idea sounds great. How thick a shim creates a significant but not extreme adjustment?

Sensitivity of the barometric cell is about 0.58mm per 100m Hg (4.41mm per atm)

Going from 2.2L to 2.4 L is about a 9% increase in capacity

Assuming similar volumetric efficiencies between the engines, try 0.4mm or 0.5mm shim and use an 02 Lambda meter to put you in the ballpark.

Make sure you check the AFR with an 02 Lambda meter...you need to avoid a lean running situation

Your 2.2 pump should work OK for the 2.4E.. mine did for a decade or more...

However Clay I'd love to know how you get a standard 2.2E pump to work on a 2.8...

Even overhauled and recalibrated we could not get the 2.2E pump to work properly over time on a 2.7E engine...we could work it fine on the dyno... great figures.. smooth as glass...but 1000 miles later it was 'off', running too rich.