well i got my car running again. it was just a bad battery. i drove it a little the other day before it started raining and it ran pretty good. it wasn't hesitating that much so maybe the battery was a problem. i'll know more when it dries up and i can test drive it again.

scott

Good luck Scott, as you can, see questions on the MPS go deep fast, You have had the best, in responce to your request.
Joe

You can borrow my Janbo sometime Bruce to trace down your problems.



Geoff

Thanks Geoff. You've offered it to me many times and I appreciate your generosity. I will take you up on it.

The weather should be changing for the good in a short time & I'll take a drive up your way to see my sister and stop by to have a beer wit'cha.

How does the Janbo work? and what is it connected to so you know what's wrong with the car. It's strickly FI trouble shooting, right?


.........b

You plug it in with the main FI plug to the machine. It has a pee brain so you can start and run the car while you troubleshoot. Pretty much a go-no go type of tester but it works by telling if everything is operating or not. Has some tests that displays readings too to evalue.
Its not a tuning device.

Geoff

Testing the resistance of the primary and secondary coils just verifies that the coils aren't open or shunted. It doesn't provide any information as to whether or not the MPS is actually responding to the vacuum signal. The Janbo tester mentioned has a rudumentary circuit that gives a range of response to a 15 in. Hg vacuum level, but not the detailed data needed to tell if the unit is calibrated properly.

Here's my line of testing/logic for an MPS if you don't have an analytical tester (see my testers page):

1. Test to see if it holds vacuum. A lot of units I see can be pumped down to 15 in. Hg, but quickly leak back up to atmospheric pressure in a minute or so. If the unit is an OEM MPS, and hasn't been rebuilt (OEM has rivets holding the case together, rebuilts have screws), then if you have a leak it's very likely due to a crack in the full-load diaphragm, and the unit will continue to degrade until it no longer works, and needs replacement. If it's a rebuilt, it could be leaking from a number of places. If you're brave, you can open the unit and reseal it, but it's likely this will affect the calibration of the unit. If you decide to do this, do NOT change the settings of the screws in the full-load diaphram, and to not tamper with the full-load limit plug in the end housing.

2. Test the coil resistances. If you find a shunt or open, the unit is toast and needs replacement. It may be that in the case of an open, a lead from the coil to the plug may have broken, and could be resoldered, but it doesn't happen often.

3. If you've passed tests 1 and 2, and the unit is either a) an unmolested OEM unit, or b) an unmolested rebuilt unit, then it's very likely the MPS is functioning properly. The only caveats to this are:

i) The MPS is the wrong part number for your application (check
my web page for part numbers)
ii) If it's a rebuilt, the unit may be miscalibrated for your
application. Apparently, the main rebuilder (Bret Instruments)
only uses one calibration setting for all of their rebuilts.
iii) The aneroid cells may have a leak in either one or both cells
iv) There may be a mechanical problem with the unit. This could
be the failure of an internal leaf spring or some other
component. It is also possible that debris/dirt may have
entered the end housing of the MPS through the vent slot,
and is jamming the movement of the full-load diaphragm.
Check by bright light inspection.

This is the most you can do without a tester. Good luck!

That's very good info. I doubt very much that I'll be taking my MPS apart. The closest thing I'll do is use Geoff's tester.

I installed the Pertronics last night. The car started and idled very smooth. I'm thinking the dizzy is worn so I'll settle for the electronics. Checked all my numbers of the components from your site Brad, and it seems they are correct.

thanks again all.... b