MSefi.com read only forum (Jan.15,2018)

I'm a "wire guy" replacing the Rochester carb on a Chevy 350 with a MS I driving a stock GM 2 BBL TBI unit. I do fine with basic mechanic work, but I'm for sure no ace mechanic hot rodder.

I got a really cheap deal on what I now believe (having read more in the FAQ and some other sites) to be the wrong fuel pump for what I'm trying to do.

The pump is a MSD Fuel Management p/n MSD 2225, which evidently is a "performance" unit capable of producing up to 125 PSI (at zero volume, I would guess), but still 30-50 PSI at a fair output volume (according to the flow graph on their site).

Given all this:

Will this pump "overpower" the internal TBI 10-13 PSI regulator, forcing it to output too much/erratic pressure to the injectors, or am I OK?

If this is a problem, can I fix that problem with an external regulator set for a low pressure, maybe 20-30 PSI?

And if I do that, can I plumb the return line from the extra regulator into the same return line the TBI uses without producing problems? It's a non-stock gas tank setup, and getting to the tank to add another return port would be a big pain, to say nothing about me really not wanting to do any machine work on a gas tank.

Or, is all of the above futile, and I should just get a different pump? If so, any recommendations for an outside-of-tank electric unit?

Thanks a LOT for the help!

Mike

REF:
1960 Chevy PU
stock Chevy 350 V8 w/ 4SPD AT
stock Chevy TBI unit
MS I, firmware 3.0

I've run this same basic pump on low pressure TBI's with no problems.

You need to make sure that the return line is at least 3/8" hose all the way to the tank with no restrictions.

This ain't a bad way to go....you won't have to change the pump when/if you eventually switch to port injection.

Thanks for the tip! As long as I know that TBI regulator can deal with the input pressure, I'm good to go.

Understood on the need for the 3/8 return. If that line pressurized at all, there would be no way to maintain control.

Thanks again,

Mike

Interesting! I hadn't considered the problem in that light. Makes perfect sense, though.

The case you described sets up a much wider functional window that what I had in mind, which is obviously good.

Very good to hear that you use the same p/n pump on a GM TBI installation. You just about can't beat a "worked before, I'll work again" solution to a problem.

Noise isn't a factor for me, though. The racket in the cab of that truck is such that I expect the only time I'll ever hear that pump is when I turn the ignition on before the engine starts. A Lexus it ain't!

Once again, thanks for your help. You guys are really great. It's very good to know that a pool of expertise exists to help me get past rough spots.

Mike