MFI Mechanical Fuel Pump - Help Needed!

[M491]

I have some questions for the experts! I have a 1972 2.4 911T engine currently in my 1972 911T that is extremely good health, with 97% and 98% leakdown results on all six cylinders. The engine in the car has a 2.4 E (014) pump on it, but my mechanic (ASG in Fairfax, VA) tells me that pump might be in need of a rebuild soon. Notwithstanding the mechanic's prognosis , this car is really making me happy! It's quite cantankerous when cold, but when it's warm, it feels great to me. The idle even holds at 950 to 1000 RPMs. Hats off to ASG!

I also have another 2.4 liter engine currently on a stand being completely rebuilt with 2.4 911S heads, 2.4 S Mahle pistons and cylinders, E cams, magnesium 911S MFI stacks, and I'm currently planning to use a 2.2 911E,freshly rebuilt mechanical MFI pump.

OK, so here are the questions/problems: First, I am now having some untimely doubts about the 2.2 911E (010) MFI pump because I'm not sure it will have a fuel curve that will be useable on either my 2.4 liter 911T or the rebuilt 911E/S spec engine. Do you know if this pump would work OK on either or both engines?

Second, does anyone have one or two known very good or rebuilt 2.4 911E or 911T (014 or 015) (or even a 013 2.4 911S) MFI fuel pump(s) for sale? I say "two" just in case the rebuilt 2.2 911E (010) pump would not work on either of my engines. Any info would be greatly appreciated!

[csbush]

I would just call Gus Pfister at Pacific Fuel Injection.

I have used him several times, and he is great for offering advice, and could probably help you find the pump you are looking for or convert one you have.


153 Utah Ave
South San Francisco, CA 94080

Tel. +1 650.588.8880

[orange911]

As for the pump that is currently running, I would not rebuild it if the motor runs great when warm. You need to look into cleaning out the thermostat that richens the pump when cold. When the stat gets warm it leans back out. Your stat could be working, but the mixture just isn't right, or i just needs a good cleaning. Investigate the number of baffles and washers before taking apart. This is an easy DIY you can do without special tools.

I can not give any advise on matching the pumps with custom builds. Gus will be the best to consult with for that.

[hbrand]

Have 013 Pump for sale, just serviced and tested in 2.4 911S engine. would have everything else for a complete S system. Paid top dollar 2 years ago,
bmcar1@aol.com

[M491]

HBRAND, I'm interested in buying that 013 pump and setup. I'll email you. Thanks.

[VintageExcellen]

I spoke with Gus a few times, it is funny how he complains about too much work to do. He told me he wished people would stop sending him perfectly good working pumps to be rebuilt. That statement should tell the rest of us that you should do everything you can to make the injection work and only as a last resort send the pump out.

Anyone know how long it takes Pacific Fuel Injection to build a pump? I have a 015 pump up there now, been there 3 months. I called Gus the other day and he said he would try to get on it this week.

[drwhosc]

M491

do a search in the pelican archives on open heart surgery for a MFI pump. It will tell you all you need to know. You can adjust these things to meet your needs. Not for the folk who want a quick fix. I also agree if the engine is running well when hot, your pump is probally OK, but you should check the fuel to air ratio to make sure. A winde band O2 sensor is a must if you are going to try to adjust these things. they are very tricky to get just right. Even if you put a rebuilt one on, you are still going to have to tweek it to get it right. BE PATIENT

[304065]

First of all-- it's a common belief among even professional mechanics that if something's going wrong with the injection it HAS to be the MFI pump. Most of the time it's something else-- NOT the pump. That's why the factory published CHECK MEASURE ADJUST way back when-- they got tired of warranty claims on the MFI pumps caused by other subsystems being worn or improperly adjusted. So remember any competent porsche driver tracks faster if brakes come smoothly and tell ASG to check the air filter, compression loss, plugs, dwell, timing, fuel pressure, injectors, belt, correlation and smog (CO) and THEN give you advice on your fuel pump.

Poor Gus, he's swamped. It took him several months to get to my 010 pump in the race car, and when he finally got to the pump, it took only one day to complete. But worth it-- and my pump was genuinely broken, it used to stick in WOT!

Anyway to your question. Check over on Pelican, search for the "MFI open heart surgery" thread that goes into exhausting detail how to tailor the fuel curve of a perfectly run of the mill 2,4T pump to suit the fuel delivery requirements of a twin plug 3,0. Not for the faint of heart but it can be done.

It is really impossible to know what's happening with the MFI system without a wideband lambda sensor- I use the LM-1 with RPM adaptor, but now the LM-2 is out which means you could mount one sensor per bank of cylinders to be sure the side links were set properly. Anyway, with that as your guide, you can make adjustments to the fuel curve that should give you a decent margin of safety. The only place I've heard concern is with high-overlap cams like S cams, where even an S pump leans out at high rpm under load with headers and megaphones. A sport muffler would probably fix that.

Good luck!