I went through the CIS troubleshooting steps using a HF gauge set back when the 450SLC stopped starting. Everything checked out good. The problem turned out to be all the rock hard rubber tubes and bits under the intake manifold were leaking air. Replaced all of those, had the heads reworked while I was there, etc., and it ran great.
On Thu, Mar 2, 2023 at 4:48 PM Kaleb Striplin via Mercedes < mercedes@okiebenz.com> wrote: > I am actually sort of having fun playing with the CIS and learning all > about it. After spending a lot of time jacking around with the HF fuel > gauge set and not getting accurate readings, I spent $130 on the correct > test set that I picked up on ebay. Within minutes I am starting to > narrow down the issue. I am running thru the tests that are spelled out > in a training doc I found on w116.org that tells you which tests to run > based on what the issue is. Test 3 tests the system pressure. This is > done with the engine off, turn key on with valve closed on the gauge > mine is dead on. Next test is testing static pressure. For this test, > you open gauge, turn key on for about 30 seconds to fill the > accumulator, then turn off. It says pressure is supposed to be 2.8bar. > Since there is not a range, I assume it must be exact? While the pump > is running it only shows .5 bar. After key is turned off, pressure > builds up but mine only gets to about 2.5 bar. The test then says > within 30 minutes it can leak down to 2.5 bar, so .3 bar leak off. > After about 8 minutes mine has lost about .4 bar. So, this is the first > issue to correct. > > Items it says to check for leaks are the cold start valve (done, it is > not leaking), fuel pump non return valve (where is this?), accumulator > for leaking diagram (is this the deal back by the pump?), pressure > compensating valve (not sure where this is either), FD for internal > leaking around control plunger or o-rings of metering sleeve. > > I will be digging into this further but this is just a quick check of > the system so far. Without throwing parts at the thing, which if these > items it a most likely cause? I figured somebody that has dealt with > CIS a lot would run into some common issues. > > > > _______________________________________ > http://www.okiebenz.com > > To search list archives http://www.okiebenz.com/archive/ > > To Unsubscribe or change delivery options go to: > http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com > > -- OK Don "Quality of life is inversely proportional to the amount of clothing you are wearing." "Whenever you find yourself on the side of the majority, it is time to pause and reflect." Mark Twain “Basic research is what I’m doing when I don’t know what I am doing.” Wernher Von Braun "In science if you know what you are doing you should not be doing it. In engineering if you do not know what you are doing you should not be doing it." -- Richard W. Hamming, The Art of Doing Science and Engineering 2013 F150, 18 mpg 2017 Subaru Legacy, 30 mpg 1957 C182A, 12 mpg - but at 150 mph! _______________________________________ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
