The regulator is rated for 35 psi above intake manifold pressure. The line pressure should be at it's lowest when the vacuum line is connected to the regulator.

You should be able to blow through the fuel return line, any obstruction in the return line (kink, etc) will cause high pressure.

 

QUOTE (robert240 @ Mar 28 2012, 12:21 PM) <{POST_SNAPBACK}>The regulator is rated for 35 psi above intake manifold pressure. The line pressure should be at it's lowest when the vacuum line is connected to the regulator.

You should be able to blow through the fuel return line, any obstruction in the return line (kink, etc) will cause high pressure.
I tried with the return line unhooked and an piece of hose running into a gas can. The pressure remained high, around 78psi.

I just bought a new vacuum pump with a gauge so I will check it out tonight. Fingers crossed.
-Chris

 

Here is what I found:
The engine vacuum at idle bounces rapidly between 10 and 16 in/m. This leads me to believe in a sticky valve. I applied a steady 21 in/m to the new regulator and the idle smoothed out considerably but there was still a noticeable skip.

I think the blown regulator caused a over rich condition leading to coking the valves with carbon causing one or more to slightly stick, lowering the vacuum signal to the regulator and compounding the problem.

Does this sound like a reasonable diagnosis?

If so, does anyone recommend a good way to clean the valves of the deposits without pulling the head? Maybe running injector cleaner sea foam like product in the oil? Product recommendations anyone?

Thanks.
-Chris

 

yes that seems reasonable, you really don't have much to loose by trying seafoam. Make sure the nipple on the throttle body that the vacuum line connects to is clean .. maybe clean the throttle body plate at the same time with carb cleaner.

 

QUOTE (robert240 @ Mar 28 2012, 09:21 AM) <{POST_SNAPBACK}>The regulator is rated for 35 psi above intake manifold pressure. The line pressure should be at it's lowest when the vacuum line is connected to the regulator.

You should be able to blow through the fuel return line, any obstruction in the return line (kink, etc) will cause high pressure.

I'm having the same problem with an 89 240 DL, replaced both pumps, regulator and filter and I'm still receiving around 80psi, I disconnected the return line and connected
a different hose that just dumps the fuel into a bottle and applied a steady stream of vacuum using my pump, to see if pressures would change and still nothing

 

please add some new stuff make some new intrusting categories.

 

QUOTE (moparmerv @ Mar 29 2012, 01:16 AM) <{POST_SNAPBACK}>Here is what I found:
The engine vacuum at idle bounces rapidly between 10 and 16 in/m. This leads me to believe in a sticky valve. I applied a steady 21 in/m to the new regulator and the idle smoothed out considerably but there was still a noticeable skip.

I think the blown regulator caused a over rich condition leading to coking the valves with carbon causing one or more to slightly stick, lowering the vacuum signal to the regulator and compounding the problem.

Does this sound like a reasonable diagnosis?

If so, does anyone recommend a good way to clean the valves of the deposits without pulling the head? Maybe running injector cleaner sea foam like product in the oil? Product recommendations anyone?

Thanks.
-Chris clean your idle control valve the piston inside may be sticking,clean with throttle cleaner or WD 40