wow congrats looks sweet- I have the same issues why does the center air intake want to really suck like a dog, and waste extra fuel alot and also smells from the tail pipe like a gas factory??/

injectors and valve lash is the next place I'd go after shoring up all the vacuum lines. vavle lash is easy to do on these ol gals

I tried a different test drive on Sunday, driving off right after starting, instead of warming it up like I had done before. The car has even less power cold, which makes me think it's an enrichment problem. When I got back, I pulled the new plugs, and they were snow-white except for #7, which was fouled.

So I decided I would, as suggested, replace the vacuum hose to the MAP unit. Easier said than done. Remove accelerator linkage, and heater hose (drain coolant) for access. Break old and brittle oil pressure line in the process. So since it was obvious the car was going to be down for a while, I pulled the injectors out for testing, noting that the seals are completely dried, with the top ones warped.

The vacuum line was original and had lots of cracks at the attachment points.

Then I noticed that the line between the regulator and the damper was really badly kinked. This is on the return side. It has to make a really tight turn, and I am surprised MB did not use a metal line or a pre-curved flexible piece. I am thinking that this may have been the cause of the high fuel pressure. So I replaced it with a piece of fuel line that has a thicker wall, and dicked with the damper mounting to make the turn a little less tight. Be interesting to see what this does to the fuel pressure.

I rigged up a tester with my K-jet unit (see picture). It looks sort of Rube Goldberg, but it worked. I left the injectors on the rail, pressurized it, and then powered the injectors one at a time. All "splatted" the same and none leaked.

The parts came in this morning, so the plan is to get it back together, re-adjust the fuel pressure, and try it out. Then maybe a MAP sensor adjustment if it's still slobbering under load.

do the valve lash while your at it

Got it back together last night with new injector seals, sort-of cleaned/tested injectors, and a new hose from the MAP sensor to the intake manifold. The seals were deformed, cracked, and hard as rocks. I had high hopes.

Runs better and differently.

Slightly rough in P/N, starts to chug when you drop it in gear. Will occasionally smooth out/idle a little higher. Revs OK but hesitation coming off idle. Chugs at low RPM under light-ish load, but now does OK if you stick your foot in it.

Worse when cold/warming up.

Any ideas on the big difference between idling in gear and idling in P/N ???

BTW, don't break the oil pressure gauge line. Or if you do, don't let your wife find out. That's a $125 item.

Chuck

this really sounds injector related, what do you mean by "sorta cleaned them"
Did you bench test the spray pattern, are they all working?
And I will say again:D- valve lash
I have been there done all this on mine
What plugs are you running>?

My yesterday post describes my injector clean/test. I hooked the fuel rails with the ends plugged up to my K-jet tester and pumped about 20 times. Then I applied power to one injector at a time. It would spray briefly and dribble with the pressure relieved. All held pressure, and all of the sprays looked OK, They all behaved identically.

Used BG44 for the clean/test.

Next I think is to take a close look at the electrical connectors, although the harness is fairly new and I didn't see any problems.

I have the valves on the list, don't worry.

See that now, great. Don't know if this will help and most folks told me not to worry about it but there is a ground in these systems,at each plug I made sure I was connected correctly to each negative plug all the way around. My theory was if it did not matter then why have +/- on the injectors. It took some work as I had to work back into the wire to determine which wire was ground., but I have a very smooth running system. Caould not have hurt the effort. I have a chart that gives the correct color for each injectors. I will have to look to my notes as to which plug is considered -

Hey guys,

I hate to jack this thread, but I know both melted & ct have both been into their fuel systems lately...

My dilemma is centered on my fuel pump/filter set-up on my 12/71 M116 R107: I'm in the middle of replacing everything fuel related from the tank to the firewall and am somewhat flummoxed. My FSM shows the set up (see top diagram & the image of my actual set-up) with the Damper (top diagram, #38) and no Pressure Reservoir (bottom diagram, #14) and everything is plumbed with antiquated fittings & hose clamps (no collar bolts). When I ordered my parts from Phil (who knows the car pretty well by now ;)) I got all the parts & fittings from the bottom diagram (which is from the CIS section of my FSM) which still has the Damper but added the Pressure Reservoir to the mix and is all updated collar bolts etc.

My FSM lists 4 or 5 generations of updates in the CIS section on the fuel pump assembly and nothing (even down to the antique hose clamps) in the EFI section...

My questions: What do your pump set-ups look like? Was everything updated at some point to include the Pressure Reg etc? Is there any potential harm/benefit in updating the D-Jet set-up with the Pressure Reg etc? Can you even get the old-style pumps etc w/o the collar bolts??

Thanks guys!

http://i24.photobucket.com/albums/c7.../djetpump2.jpg

http://i24.photobucket.com/albums/c7/mvenn/mypump2.jpg

http://i24.photobucket.com/albums/c7/mvenn/cispump2.jpg

my 72 is the set up you have and is for the Djet, and does not need the pressure regulator at the pump. IF everything else is OK you can run your D jet with a CIS set up but you have to decrease the fuel pressure at the pump. THis can be done http://www.peachparts.com/shopforum/vintage-mercedes-forum/219870-new-buzz-fuel-pump-72-450-a.html
this thread explains it well
You can get the old style pumps and set ups but they are very pricey, when mine goes south I am goign to retrofit per the thread above.
Hope that helps

Cool link, melted, thanks.

Any idea how necessary the Damper is?

Or if there is any logical reason not to leave in the pressure reservoir? (I only ask the last one because all the plumbing I have is set up to include it...I'd have to fabricate something if I wanted to delete it...)

I am not sure on that,check the pressures coming out, if they are OK then I do not see why you could not,my guess is that it may bring the pressure too low ( or high)

Started out tonight by pulling #7 plug, expecting to see fouling, but pleasantly surprised to see it was clean with a decent burn. Started it up, took it for a drive. Same lumpy idle and stumbling under light load.

Back in the driveway, I was starting to investigate the effect of vacuum on the MAP, so I hooked up the CO tester at idle and watched it take a quick dive to 0%. It's not accurate at this level, but it's an indication that the engine is running lean. So I cranked up the mixture on the ECU and the idle smoothed and the CO came up to the .5% range. But the ECU adjustment was at max rich.

OK, so why have I maxed out the adjustment, and am still lean?

So after some thought, I checked the fuel pressure with the engine idling, and found it to be 26 psi. So maybe the change in the regulator to damper plumbing had some effect. Bumped the pressure up to 29 psi and watched the CO come up to around 1%. Putting the car in gear bumped the CO up to 3.3% and it started stumbling.

Took another test drive, and except for the lumpy idle, the car was basically normal (!). Brought it back, and with the car in gear, raised the idle speed by adjusting the big screw about 1/4 turn CCW. In-gear idle smoothed out.

So something is causing the car to run a bit lean even with the ECU maxed out rich. My next step is to check out the MAP sensor. My suspicion is that replacing its vacuum hose raised the vacuum, causing the MAP telling the brain to go leaner than it was before.

What I'm learning is how sensitive this system is to any sort of change. One conclusion - it all starts with fuel pressure.

But, life is good. Now I have a basically driveable car.

Beautiful ct! Aren't they great when they're drivable? Mine will be down again until I get some more days off; maybe in 2 or 3 months...:(

I had the same lumpy idle problem (and stumbling REALLY BAD under load) when I resurrected mine. I didn't have the tailpipe sniffer, but I ended up replacing the MAP (because someone had obviously messed with the adj screw...it was stripped out), the computer (because someone had obviously pried it open & messed with it), replaced the points/ignition box with an Ignitor (this part seemed to help a lot), and tons of other little stuff (you know...little things...like the timing chain :rolleyes:). I've never seen a D-Jet that hasn't, over time, been continually mal-adjusted in people's attempts to get them to run/idle right...it's always an uphill battle. And you're right, every little change effects something, it is a very sensitive system. D-Jet is a finicky mistress.

I think if you've got the ECU max-ed out that the MAP must not be doing it's job enriching/leaning at the right times (or one of the wires in the circuit has a draw messing up the reading; the early 107s can really cook a wiring harness...).

I can't tell you how great it is to see someone document their work on a D-Jet motor like this. Your experience will be invaluable to me down the road when my M116 starts 'acting a fool' as they say. Thanks. :cool:

And Melted: When I get some more time on the car I'll document the CIS pump assembly install with pressure readings etc, on the off chance that yr pump hasn't failed & you're not doing it first ;). I just found out that the only metal fuel lines available for under the car are plumbed to fit the newer style fittings, so I'm committed now. And the console/glove box door look great, thanks!

thanks! I mean what a system- I need a master tech!