fuel pressure regulator

Hello!

I need help again from the experts. I am installing a 2.2S with fuel injection in place of a 2.2T with carbs. I have already purchased a fuel injection electrical fuel pump. Two nights ago, my carb electrical fuel pump crapped out on me. Since I really don't want to buy another fuel pump and my S engine won't be ready for a couple of weeks, I was hoping to install the new fuel pump with a pressure regulator. Is this a bad idea? Also, I am finding pressure regulators with and without return connections. I am assuming I need one without. I am planning on interupting the fuel line before the fuel filter and installing the regulator, then a pressure gage, then onward to the filter and carbs/fuel injector. Any help would be greatly appreciated.

Please advise!
BK

if you can regulate the pressure to 3# it should work. much more and the float valves will drool.there's some little low pressure inline pumps around for pretty cheap.

BK,

I don't think it will work on an MFI engine. The loop from pump to filter housing to injection pump and back to the fuel pump operates at 15 psi! And, the recirculation of the fuel back to the tank is fairly important! It assures cool, dense fuel to the injection pump!

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Warren Hall
1973 911S Targa

Warren;I know that you have a lot more knowledge that me on mfi systems but why can you not use a generic pump with a fuel pressure regulator on a mfi system.I assume the stock mfi pump puts out a certain pressure that effects how the mfi system works.why can this preasure not be attained with a generic electric pump and a adjustable regulator that has been set to the regulate proper pressure?



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Grant 75 911s targa

Grant,

I don't KNOW that a generic pump wouldn't work, but the working load on an MFI pump is quite different than the load on a pump for a coarbureted application ... and the question just raises far to many red flags for me to even think about risking an engine to find out! For one thing, 15 psi is a rather 'odd' pressure to operate at for a gasoline pump or pressure regulator! What if the 'generic' pump proves inadequate only at full load above 5500 rpm? Do you think detonation from a leaned-out condition will be recognizable before the pistons get holed?

And, just for dicsussion purposes, suppose you can get a 'generic' pump and regulator for $125. And, suppose it works OK initially, but on a long 8-hour drive a month after short testing and daily trips ... the continuous load (rather than intermittent load as on carburetors) cooks the generic out on a sparsely populated area of West Texas, Arizona, or New Mexico on the hottest day of the year in August? You could be stranded a week waiting for the proper pump to arrive ... or do you risk another generic pump?

Finally, how can you be sure the injection pump is properly and evenly supplied with fuel when converting from a loop supply circuit to a single-ended supply?

For me, there are just too many things that could go wrong and mess up a well-engineered system the Bosch and Porsche engineers perfected. While the Bosch MFI-specific fuel pump is expensive, rebuilt replacements are available. To risk making the system unreliable, or worse ... taking a chance on a blown engine, just doesn't make much sense to me!

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Warren Hall
1973 911S Targa

Once again I appreciate the responses. But I do have a question for Mr. Hall. I wanted to set the system up for MFI with the correct pump and plumbing. But if/when I went to carbs I would like to keep the same system and just crank down on the pressure regulator. ????????

Thanks again!
BK