MPS, Rebuilding the MPS Options

[Ron914]

Well I opened my MPS and found that the order in which I assembled was wrong . I installed the spacer ring over the part load stop which was wrong .I corrected this installing 1st the paper gasket(regreased) then the diaphragm followed by the spacer ring and the part load stop plate. Put it back to gather and tested and it still has a slow leak. I followed Jeff's advice and sealed the plug connection and then the area around the diaphragm center ring . I will put it back together later and test again and update .

[ChrisFoley]

I switched from a round o-ring to square in my kits a long time ago. Use grease on the round one, for sure.

[emerygt350]

I think that is exactly what I did the first time too. While you have it out, map the curve. I sent you some emails describing how...

[Ron914]

I switched from a round o-ring to square in my kits a long time ago. Use grease on the round one, for sure.

Hi Chris,
I am still having leak down issues .It's a lot better but not ideal . How about if I put the old square gasket back in ? What's your opinion on that ?
I did all the things Jeff recommended but still had significant leaking .
I figured if the connection plug could be leaking at the base why not through the pins so I covered the plug with Gorilla duct tape .Here are my results after that last fix .
Next I am going to go around the case halves with electrical tape and put the square ring back in . I will update soon .

[Ron914]

I think that is exactly what I did the first time too. While you have it out, map the curve. I sent you some emails describing how...

Hi emery,
Thanks for the curve, I will check my email shortly .Definitely will be easier when out of the car .
Ron

[emerygt350]

Although no leak is best. That leak is pretty slow so if it can't get any better I bet you will be fine.

[Superhawk996]

Get rid of the adapters

Go straight from vacuum pump to MPS

Heat / stretch tubing as necessary to avoid the adapters which are all possible leak paths then retest

[SVG223]

Mine takes 45 seconds to leak from 10 in/hg to 5 in/hg and runs lean with 22 inches of idle vacuum. I added fuel pressure and 270 ohms of resistance to the cht. It runs strong with a smooth idle at 900 rpm. It craps out above 4500 rpm, I'm probably going to send in my injectors to be cleaned, and due for a valve adjustment. Ideally, it shouldn't leak, but what you've got now should work fine. Does anyone use Permatex Form-A-Gasket No. 2 Sealant on the mps?

[emerygt350]

Mine takes 45 seconds to leak from 10 in/hg to 5 in/hg and runs lean with 22 inches of idle vacuum. I added fuel pressure and 270 ohms of resistance to the cht. It runs strong with a smooth idle at 900 rpm. It craps out above 4500 rpm, I'm probably going to send in my injectors to be cleaned, and due for a valve adjustment. Ideally, it shouldn't leak, but what you've got now should work fine. Does anyone use Permatex Form-A-Gasket No. 2 Sealant on the mps?

There are some things you can do with the mps to ensure it's getting the extra goodness at full throttle but I am not sure that is your problem. Do you have the Foley kit in your mps?

[Ron914]

Get rid of the adapters

Go straight from vacuum pump to MPS

Heat / stretch tubing as necessary to avoid the adapters which are all possible leak paths then retest

@Superhawk996 I removed the connectors and my leak down numbers are still about the same . I am at a loss . All this for nothing . I am thinking I should just by a new MPS . I know where might be able to get one but its going to be expensive .

[Ron914]

I think that is exactly what I did the first time too. While you have it out, map the curve. I sent you some emails describing how...

Hi emery , I checked all my email boxes and I never received the email , unless that information is in one of the three emails sent 5/9 .

[emerygt350]

I think that is exactly what I did the first time too. While you have it out, map the curve. I sent you some emails describing how...

Hi emery , I checked all my email boxes and I never received the email , unless that information is in one of the three emails sent 5/9 .

Yep, that's where it's at. And seriously, your mps is leaking down so slowly I really wouldn't sweat it. Your engine is going to be pulling vacuum continuously. There is no way it will cause any affect on the djets performance. Get the curve done and post it. Tomorrow I will let you know how deep into my mps the inner screw and outer screw is at 0 and 20. That will potentially give you a sense of how far off you may be. Each motor and mps is going to be different, but not that different. Very small changes (1/4 turn) on that inner screw have a big effect.

[Superhawk996]

Get rid of the adapters

Go straight from vacuum pump to MPS

Heat / stretch tubing as necessary to avoid the adapters which are all possible leak paths then retest

@Superhawk996 I removed the connectors and my leak down numbers are still about the same . I am at a loss . All this for nothing . I am thinking I should just by a new MPS . I know where might be able to get one but its going to be expensive .

Don’t give up.

It got better. Did you add some additional grease to the paper gaskets? Did you revert to previous OEM seal with some grease?

I hate to ask but how tight are the fasteners holding the stop plate. Torque is sort of a black art. They need to be tight but you also have to have some feel for it. When I did mine someone had been in there already and stripped one. I ended up helicoiling it. But the bottom line is they need to be reasonably tight.

[rjames]

Get rid of the adapters

Go straight from vacuum pump to MPS

Heat / stretch tubing as necessary to avoid the adapters which are all possible leak paths then retest

@Superhawk996 I removed the connectors and my leak down numbers are still about the same . I am at a loss . All this for nothing . I am thinking I should just by a new MPS . I know where might be able to get one but its going to be expensive .

Don’t give up.

It got better. Did you add some additional grease to the paper gaskets? Did you revert to previous OEM seal with some grease?

I hate to ask but how tight are the fasteners holding the stop plate. Torque is sort of a black art. They need to be tight but you also have to have some feel for it. When I did mine someone had been in there already and stripped one. I ended up helicoiling it. But the bottom line is they need to be reasonably tight.

(IMG:style_emoticons/default/agree.gif)

I tighten them slowly and check to see if when it holds vacuum along the way. Once it holds vacuum, as long as the screws feel tight enough, I don't tighten them down anymore.

[ChrisFoley]

Problem with the old square o-ring is that it will have shrunk enough by now to not be any better than a new round one.

[Ron914]

Get rid of the adapters

Go straight from vacuum pump to MPS

Heat / stretch tubing as necessary to avoid the adapters which are all possible leak paths then retest

@Superhawk996 I removed the connectors and my leak down numbers are still about the same . I am at a loss . All this for nothing . I am thinking I should just by a new MPS . I know where might be able to get one but its going to be expensive .

Don’t give up.

It got better. Did you add some additional grease to the paper gaskets? Did you revert to previous OEM seal with some grease?

I hate to ask but how tight are the fasteners holding the stop plate. Torque is sort of a black art. They need to be tight but you also have to have some feel for it. When I did mine someone had been in there already and stripped one. I ended up helicoiling it. But the bottom line is they need to be reasonably tight.

They are very tight but not stripped . The new ring is in there.

[Ron914]

Problem with the old square o-ring is that it will have shrunk enough by now to not be any better than a new round one.

@Chris Foley, @emerygt350 , @Superhawk996 , @MDTerp
I put a little dielectric grease on the old square ring and I am now showing a couple of hours for total bleed down . I think I will disassemble the complete MPS and start over since I and not getting the correct amount of deflection on the hex tool when I add vacuum from 4-7inHg to create my curve. I will also put a little of the dielectric grease on the small ring on the inner/outrer screw .The measurements I took for my full load stop screw was 1.72mm and my inner/outer screw was 5.46mm . The copy of @MDTerp 's instructions he sent showed his measurements as 1.97mm /Full load stop screw & 6.51mm for inner /outer screw.
I am hoping for better leak down results and then I will try my bench testing for my curve next .

[Superhawk996]

(IMG:style_emoticons/default/smilie_pokal.gif) you’re getting there!

[rjames]

No need to crack it open again to adjust if you have the adjustment tools. And you’ll ll need them for fine tuning after reinstalling the MPS in the car anyway.

[Ron914]

Well after putting the old square O ring back in and testing I still cannot maintain o leak down for 30 minutes @ 15 inHg but I left the vacuum gauge hooked up over night and I still had 3 inHg in the morning so I feel this is the best I am going to get . I did my bench test and created my curve . Possibly if I could find a replacement for the square o ring it might get better . I finished verifying spark at all four plugs and decided to try and start it again. It still still barely started and I could not keep it running so I took a break and then got back to it yesterday . Look what I found hiding under the air injection tube after removing my air cleaner . Reconnected the disconnected ground and the car no started but not running all that good . I had to turn the knob on the ECU to full rich to get car to idle . I now showed vacuum on my gauge but it definitely is not running as well as it did before the MPS build . I guess now is the time to play with the fine tuning of the MPS after I study up more on this procedure . Updates to follow next week .



I noticed this factory number on the aneroid cell and the housing ,maybe interesting or not .