fuel pressure regulator

[Arthur Dalton]

Originally Posted by 3BENZER

OK, I let it idle for a while till it reached just above 175 mark and holding steady. then I checked it again after few minutes and could hear it pulling air again but not as much as start up.

OK.

One more trick..
When it is warm, give that tower that the hoses hook to a few light taps with a wooden handled screwdriver..that may seat it...if not, it has to come apart and entails a little work.

Here is one other thing I want you to do:

On the intake is the throttle plate/venturi. POP that linkage ball off that lever and with the car at normal temp and at idle, I want you to very slowly OPEN the throttle plate , allowing MORE air [ the FI pump rod will not move with this test]
If the RPMs speed up in rpms a couple of hundred, the mixture is too rich. If you find this to be the case. pull a plug and see if it is carboned up..

Post findings.......

[3BENZER]

Tapping the tower didn't change much in terms of air getting pulled in.
The other test did very much like you said it would. The RPM went up ever so slightly but noticeable. I pulled one of the plugs and there is a very fine coat of carbon on the plug.

[Arthur Dalton]

OK...


Inside the tower is a thermo chamber with a pin sticking out the bottom As the water heats it up , the pin extends and pushes down on the air slide and pump lever to lean the mix out as the temp goes up. If the air slide does not completely close , it is either sticking partially open from dirt or gunk, or the themo pin is not extending far enough. Both woll cause RICH running condition.

You can take that tower apart and then you will see whats up in there ..you can also put the thermo cylinder in a pot of water and heat it to watch if the pin is extending. The amouint of pin extension is dependant on the pump R#. [ side of pump]..your is most likely an R20 or 22

Anyway, this procedure take a little finesse, so if you are up to it, make sure you take the water hoses off first and blow the water out of tower b/c you do not want a/f in the pump. If everything is clean and not binding and the air slide still does not close all the way, there are shims in there that you can take out to make up the difference and there are shims to make the PUMP run leaner. It is quite common on Bosch MFI to run rich as they age and many times just removal of a shim between the tower and the pump is enough to bring the a/f mix back in line.
It is recommended to use gas analyser for this procedure, but your first check will be to see if the tower WRD is full of crap, as is often the case ..you will know if you have been successful b/c the air slide will then completely shut off air at normal coolant temp. If it requires cleaning, oil everthing up with fine oil [3&1 type] as you re-assemble, specially on the air slide .
There are other adjustments [ linkage,etc] that effect a/f mixture , but we are not addressing those until the air intake problem is resolved b/c all other adjustments can/should NOT be made until this aux air intake is CLOSED.

[3BENZER]

Arthur,
Thank you for your patience and superb instructions, I will take the tower apart in the morning (as I have to deal with the kids now) and keep you posted.

thanks again

[3BENZER]

Arthur,

I took the tower out and pulled the thermo chamber with the pin out of the tower body. First of all , there was a lot of dirt and grime at the base of the tower and on the inside edge, but the inside of the lower portion is relatively clean and I made sure I didn't let anything fall in there. I have cleaned everything out and just want to make sure I get at everything while I'm here. Do you want me to take the lower portion (the section between the tower and the FI) out as well?

[Arthur Dalton]

Well, the main thing is to make sure the air slide is nice and clean/free..use some oil too. Here is a post that has some info from another site, but the info also fits your chassis. Note that the main concern is that the air shuts down completely when the coolant is up to temp. I would also make sure you are getting water circulation, so feel that the tower gets HOT ..if it just gets warm, then the problem can be coolant circulation. Read this and separate what fits your condition and this will also give you a better idea of the working of this unit. Once you have the air shutting off, I can walk you thru the mixture steps.

http://www.sl113.org/forums/topic.asp?TOPIC_ID=1386&whichpage=1&SearchTerms=thermostat%2Cbulb

[3BENZER]

OK,
Everything is nice and clean all lubricated. The airslide functions smoothly (I can press it down all the way without binding and catching). The Thermo chamber checked out OK (I did the boiling water test and the pin extends properly). The coolant circulation is good, the tower feels as hot as any part of the system.
There are 4 shims of various thikness inside the air slide held in place by a locking ring. I will take the two thinest ones out and put it all back together and try it.

[3BENZER]

Well,

I put everything back together and started the car. It ran rough (didn't before) till it reached the operating temp, then it smoothed out but lots of black smoke. the airslide did not shut off the air (actually it didn't change much from when it was cold). The airslide felt smooth when I pushed it in during cleaning and lubing, but quite stiff, so not sure what I've got here:
1- could it be that the plunger does not have enough strenght to over-come the airslides spring resistance?
2- Did I take one too many shim out?
Now I have to wait for the engine to cool off to check things again.

[Arthur Dalton]

I would have left the shims in so you could see if the cleaning and oiling had any effect ...may want to do that first. The most common problem with these is sticking from dirt or pin is not protruding w/temp increase [ you have determined that]
Shimming is done once you know the unit is working freely and is changing with temp increases .. I think you are getting ahead of the required steps.
It is also possible that you have an air trap in the water hose to tower ..that is common when reassemby on these and that would account for the no change condition of intake air. ..a lossening of the clamps can test that [ air bleed]
Double check that you put it back like you took it off, too.......
The little ring/spacer under the tower always eludes one when taking the tower off/ apart..it ususally drops off and winds up down between the pump and the block..

[3BENZER]

Thanks Arthur,

Everything was put back the way it was (minus the shims), and I did check for air trap at the time. I agree with you, I should have left the shims in to start with. I will re-try with them back in place and post back.
cheers

[3BENZER]

Success at last,

I put the shims back in and did a test run, everything works the way it should, the air stopped being drawn in at operating temps. thank you Arthur, your help was fantastic and very much appreciated. Hope you still have patience to continue on.

[Arthur Dalton]

Originally Posted by 3BENZER

Success at last,

I put the shims back in and did a test run, everything works the way it should, the air stopped being drawn in at operating temps. thank you Arthur, your help was fantastic and very much appreciated. Hope you still have patience to continue on.

OK

Did you want to tweak the settings ???? ..it is a little entailed.

[3BENZER]

Originally Posted by Arthur Dalton

OK

Did you want to tweak the settings ???? ..it is a little entailed.

Sure, why not.

[Arthur Dalton]

Ok

A few test ..

Do that throttle richness test again....

And then, when up to temp, I want you to turn the air bleed screw for idle In and see if you can stall the engine... Take note of original screw position b/c we want it back there after , as this is just a test to see if we have any other air intake leaks.

[3BENZER]

OK, the throttle richness test had the same result, slight increase in RPM.
I turned the air bleed screw in one and a half turn and it stalled.