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914World.com _ 914World Garage _ MPS testing...

Posted by: MikeM May 11 2020, 02:00 PM

Hi all...does anyone have the procedure to test the electrical part of the MPS?
Thanks!!

Posted by: Bleyseng May 11 2020, 02:07 PM

https://members.rennlist.com/pbanders/DJetParts.htm

99% of the time the MPS diaphragm is what goes bad by cracking or completely separating to cause a massive leak.

Posted by: MikeM May 11 2020, 02:08 PM

Thanks...I should have thought of that.....

Posted by: GregAmy May 11 2020, 02:24 PM

If your diaphragm has not been replaced since new, it's almost certainly damaged.

http://www.tangerineracing.com/mpsdiaphragm.htm

Posted by: MikeM May 11 2020, 07:28 PM

We vacuum tested the diaphragm and it holds solidly. Seems there's a problem with the secondary coil...
Thanks

Posted by: GregAmy May 11 2020, 08:06 PM

QUOTE(MikeM @ May 11 2020, 08:28 PM)

We vacuum tested the diaphragm and it holds solidly. Seems there's a problem with the secondary coil...

My MPS held vacuum overnight and tested fine. When pulled apart by Chris Foley at Tangerine Racing it was torn. http://www.914world.com/bbs2/index.php?showtopic=291477&hl=.

I've absolutely never heard of anyone having an electrical problem with the MPS. It's a barometer that relies on a 50-yr-old metal diaphragm.

But...it's your game, man...

QUOTE(GregAmy @ Apr 28 2017, 07:54 AM)

Just a quick follow up...the car is totally transformed. For those of you that have never experienced a bad MPS, trust me, this is like an automotive religious experience. Just spend the money because now my car that ran like total hell is a joy to drive: starts, idles, runs smooth, warms up nicely, and doesn't die when I push in the clutch at a light...with this system running correctly all thoughts of carbs is long, long gone.

Posted by: MikeM May 11 2020, 08:34 PM

Thanks for that...I had a spare MPS and the car runs great. I was just messing around with the old one. I tested the electrical portion as per the pbanders info and it looks like the failure is in the secondary coil.
Thanks

Posted by: DRPHIL914 May 12 2020, 05:04 AM

QUOTE(MikeM @ May 11 2020, 10:34 PM)

i had had a electric failure in an mps as well so they do happen, and it was very frustrating trying to track down the issue. it was intermittent, so difficult to see that it was the mps , but also have had the diaphragm failure but vac was holding, and that was just recently. you have a spare so while you are using that one take your failing one apart and look at that diaphragm, if it’s torn rebuild it with the kit from Tangerine, and the. retest it, of get a cheap core to rebuild . but for proper calibration you real need to send it to someone like Jeff Bowlsby who has the LCR Wavetec meter that can do this.

good luck,
Phil