Injection pump check valve

[philmas]

Unfortunately, you were right …they refunded me as the part is out of stock!
Let’s hope Bosch will start a new production some day, or someone willl re-manufacture the valve…

[roymil]

Seeing that picture from Chuck Taylor (earlier post) showing the disassembled exit fitting from an R11 FIP made me wonder if it might be possible to replace the spring to increase the back pressure?

Has anyone had experience disassembling the check valve and accessing the spring in an R22-R25 series FIP?   

If that seems doable I'd think we could measure the spring force and try out some different springs to find the one that would create the back pressure needed to maintain ~15psi.   Alternatively might look for an aftermarket pressure regulated check valve that is constant over the under-hood temperature range.

[ctaylor738]

Bonjour Philippe,

The easiest way to check for the bad cylinder is to pull all the spark plug wires off the plugs but leave them in place just barely attached.  Then start the engine and pull each cylinder's wire off and see if the idle gets worse.  You might want to use a pair of well-insulated pliers.  When finished, reconnect the wires securely.

You can also test by loosening the connections at the injectors, and retightening them just until they seal, then loosening them in turn with the engine running.

Bon chance,

CT

[roymil]

you might want to rethink the loosening of injector lines on a running engine.  There possibly could be better and safer ways of troubleshooting that don’t involve dripping raw fuel onto hot exhaust manifolds.  I dunno,  Maybe just me? ;-)

[philmas]

Thanks again, this makes me think Icould as well check the fuel lines tightening first, who knows…

And the issue could still come from a leaking injector, or a dirty check valve in need of cleaning, not necessarily replacing.
The engine has ben running this way for thirty years, and I think I can cope with it as this is only a two or three minutes wait  when the car has sit for some weeks …until the melody of the inline six is back again!

[bracurrie]

Your probably right about just accepting the problem.  Especially if its after the vehicle sits for a while.  These cars are sometimes just not perfect. The question is how much trouble, time and/or money are you willing to spend to chase whatever issue that just doesn't matter when the car is warmed up and eating up the highway like only a Mercedes Benz can.

[ctaylor738]

If you pre-loosen and then tighten the injector fittings, only a tiny amount of fuel will come out when you loosen them a bit to do the test.  Keep the wrench on the fitting so you can re-tighten it quickly.  If you want, you can stick a rag under the fitting to cause the tiny amount of fuel that might escape.  I hate cars catching on fire as much as anyone, and I have done this many times.