Carter Fuel Systems reman'd MPS?

[bradself]

Any long timers have any experience with these, Federal Mogul brand. One better thing is the adjustment screw is covered with soft caulk type material rather than hard resin.

Even if it has a crap brass diaphragm it'll make a good core for the Tangerine (?) kit.

[raygreenwood]

The problem with every rerbuild I have ever seen.....is that they are massively out of adjustment.
So.....as long as it can start the car with it.....you can at least adjust it.....but they take a lot of tuning.

Also in the past.....the few I have tried that were remans.....did not appear to have been bench set with vacuum applied. All that bench setting is really capable or useful for is to set the inner stop at max vacuum so that at idle the vacuum doesnt automatically drive the armature into the coil to surpass minimum lean....or push the armature past the point of minimum response in the coil.

If you are going to put in a new diaphragm anyway.....I would think you could find just a core with good coils fairly easily for a lot cheaper. As long as the coils are good and its not rusted you should be able to drop in the kit. Ray

[bradself]

These were a wholesaler close out, very cheap, cheaper than used ones. Worth it just to have the case opened, tapped, and the resin over the plug removed, they were that cheap.

I do wonder how they were set up at Bosch and why that was so hard for rebuilders to replicate. From past posts I think it was determined these are basically variable inductors, am I remembering that right?

[Lars S]

Yes the inductance varies with the (under)pressure in these MPS.
They surely could have been made with a variable resistor instead (just like the tank armature or the TPS) but the pressure varies all the time and a resistor with a sliding pickup would wear out, inductance however can be read without a pickup.
I believe they are quite advanced engineering for its time and to service the interior parts really one need to fully understand its total function in detail. Today the MPS is wey well documented on the web.

Lars S
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[raygreenwood]

Yes....as Lars noted. Also....since they were used on very few types of vehicles and only for a few years....I think you would be hard pressed to find any reman company that even has baseline knowledge of what these do and how they work.

The vacuum set up for baseline....which has nothing to do with whether it will work on your engine....is putting a vacuum signature within a specific range to the unit and then adjusting the armature stack until you get acceptable maximum lean signal...meaning that no matter if your engines vacuum signal is slightly higher than the test signal...the internal armature stop is set so that the unit can never draw the armature into a position that is beyond the signal detection scope of the inductance coil...which would cause a hard stall repeatedly and you could probably never get it to run rich enough under vacuum too even start....without outside enrichment like very high fuel pressure

From there....you adjust the main fuel mixture adjustment and the outer full load stop on a running engine....not on the bench.
If you really know the baseline engine vacuum characteristics and can match the oscillation caused...you could do this on a bench. I am sure the factory did.

This is why they are so far off when you get a reman that you should bench test to make sure the inner full load stop is adequate to allow running. The rest is just tweaking. Ray

[bradself]

Car starts and runs, just moved parking spots tho, haven't taken it for a spin.

The copyright for Federal Mogul on the packaging is 1988, so these have been languishing for some time. I wanted a spare so I could pull the outer stop plug out of my factory riveted original one without disabling the car, or having to continuously pull it/reinstall it so this is fine. And really, they were jaw droppingly cheap, it was a no brainer. I could likely resell one on eBay to a 914 guy and be more than half way towards an AFR meter, so I don't have to tune by ear.

[raygreenwood]

Just remember to count the turns as you back that plug out.....so you dont have to tweak so much once you put it back in....though I have found that a tweak to the outer stop....the plug....is typically a good thing for most engines.

Ray

[raygreenwood]

A little bit more on this.....in reality.....on any remanufactured MPS I have ever seen.....and looking back I think I have used about a dozen but only two on my own, vehicles.....and I have poked around in I think maybe four of them (meaning I have opened them up when they do not run right).

Really remanufactured is a loose term. Every one of these had simply been cleaned carefully, at least most look like they had the solder on the connector pins reflowed and one at least had more epoxy applied....but all had the original coil and aneroid chamber. The only parts that were replaced were the diaphram and the o-ring.

A careful reman company knowing nothing about these units could simply rebuild undisturbed units with broken diaphrams, measure the inner and outer full load stop gaps....and simply put it back in the exact way they found it when they replace the diaphram....check the resistance of the coils.....and replace the o-ring....and do no other adjustments and the unit will largely be fine.

You will have to do the fine adjustments for your engine either way.

The units I got....more than half....that simply would not idle until major resetting of the inner full load stop......were probably units that were disturbed cores when they came in....meaning the PO had tinkered with it and messed up the inner stop adjustment which is most common.

Also the first couple I got that were remans were not even the right units. The reman company had ground off all the original numbers and renumbered them with generic part #s.....probably not realizing that while yes.....many similar units can be adjusted to run from one car to another.....wholesale changes like diaphram spacing and main armature spring length cannot be swapped.

Post some pics of what you got when you have time. Ray

[bradself]

Sure! One has the # ending in 049 but no VW number, the other has no numbers at all. No Numbers is way out of whack, won't idle without the ECU knob turned way high on idle mixture, haven't tried 049 yet.

But as I said, it's not a biggie. I can practice adjusting with these and still have my own factory riveted unadjusted one which simply runs rich at present. The two recently acquired reman's are basically cores, afaiac, might work, might not. Dinner for 4 at McDonalds would have cost me more.

They had to have been twiddled with some, as the resin was removed from the outer stop, As I mentioned it was replaced with soft caulk and painted along with the cover. The benefit being not having to dig out hard resin to get at it.

Air Fuel ratio meters have come down in price substantially since their first appearance. My plan all along was to install the O2 sensor in the collector of my Thunderbird header, use the header basically as a temp exhaust, and a part of the meter more or less, until the mixture is tuned and put the much quieter Ernst back on. Goo digital meters w/lcd readout and 8 feet of cable for the sensor run about $200 these days.

Pics soon

[bradself]

I have three spares total, two from the so called Carter Fuel Systems acquired recently, one from Fuel Injection Corp which we've talked about in the past here.

I took apart a Carter, chose the one with the part # sanded off. I discovered a hole drilled on the outer stop plug; the plug got jammed on bad threads and now won't budge. Inside, the diaphragm cover was sealed with clear silicon, the diaphragm was copper, between two thick paper washers, each layer silicones together and to the cover. Sadly the diaphragm was cracked along the edge. The coils test fine, static resistance between the inner contacts is 250, outers is 50+ (the battery in my tester is weak but these are consistent readings with the other 2 sensors.)

Correct square o-ring, so that's something.

The other Carter ran the car similarly, needed lots of idle fuel at the ECU, but it holds vacuum, the outer stop plug came out easily. Was likely poorly adjusted in the past, using only the mixture screw and spinning the inner stop screw at the same time.

If anyone knows off hand, let me know the size hex on the inner stop plug, I'll fetch some plastic hex bar to make and adjuster tool.

[bradself]

Appears the same as all others here, more corrosion and rust than the cleanest Fuel Injection Corp one, which is very clean. The backs on these two newer ones have a raised 030, this one has smaller stamped 22, the other just 2.