Day late and a dollar short, but a CIS fuel pressure test gauge would have been essential in configuring the system to proper spec instead of throwing parts at the problem.

You still have to modify the air fuel metering screw after swapping out so much. Your no start may be caused by this being crazy out of whack.

Here's a trick to get you in the ballpark:

1. Remove one of the injector hardlines.
2. Jump the fuel pump to pressurize the system.
3. Look at the open injector hardline port. If gas is coming out of the top of the port, turn the metering screw counterclockwise until it just barely stops. If nothing is coming out, turn it clockwise until fuel just barely starts to come out of the hole.

Have a bunch of shop towels handy to wipe away the fuel. This will get you close enough to "running". From there, you will need to bring out the duty cycle number on pins 16 and 17 within the jetronic ECU that lives behind the passenger kick panel.

You cannot use pins 3/2 on the x11 port unless you have an oscilloscope or multimeter that filters out the PWM portion of the signal.

There is no ECU; 1976 is K-basic.

My bad, looks like a CO2 sniffer is what is required next.

TY, knew it was fuel pressure something or other.

It's been a few days since I've had time to play with the 450sl, but I started replacing rubber vacuum lines that were hard, and all the hard plastic lines started breaking,,, the I had trouble removing the warm up regulator.
After busting the nipples off one of the temperature sensors (and repairing with hard plastic vacuum line and JB weld, I'm close to the point of putting the new mixture control unit, pressure damper, and warm up regulator on the car.

Thank you. When I get everything back together, and she still doesn't start I will do that.
When I first got the car, the Fuel Distributor was leaking, seems like someone took it apart once already. After replacing that, and having the same exact issues, I decided to swap out the parts from my part car (which I know runs)


i do wish I had the Bosch equipment, but I do not. I will probably take it to a friend who has all teh necessary tools to tune up the fuel system.

How long had it been since it had run? On every old gasser I've ever resurrected I had to go through complete fuel system from tank to engine. How does the screen in the tank look?

I've had good luck purchasing good, used fuel distributors. I have not seen a FD taken apart and put back together successfully.

OK, So, I replaced the fuel distributor, mixture control unit, presure damper and warm up regulator, but still have the same problem. If I disconnect the cold start, then I get no start.

You can hear the fuel pump running in this video,,

https://youtu.be/cHdEij5X3UM

So, maybe the fuel pump isn't delivering enough fuel, or the accumulator is stuck, or the pickup screen is blocked and restricting fuel flow.

I adjusted the mixture control unit two 360 degree turns in both directions, didn't notice any change.

The above parts were pulled from a known running 450SLC 1976.

Did you try my suggestion above?

The air mixture screw is like a regular old screw. Think like a regular old wood phillips head screw. Turning it 360* in either direction won't reveal anything if the screw has to be turned 440* clockwise to get it into spec.

Another trick you can try if you don't want to go through all that is have a helper try to start the car while you push down on the air horn in front of the distributor. If the car tries and stumbles and runs a bit longer after cranking, you're running rich and need to keep turning the scew counterclockwise in MINOR increments while a helper cranks.

If it dies instantly then turn it clockwise in increments until it runs.

I have no idea how long she sat. But the PO had taken her to a mechanic who had tried getting it running. New ignition coil, plugs, wires,,, I'm thinking he replaced the fuel filter and maybe pump.

The mixture screw I am aware of is I think 4mm hex

Since the FD works on the other car, you can pretty well rule it out. I'd be looking at fuel pressure at this point to find out what's going on. Just because the pump is running doesn't mean it's any good!

M:

As Diseasel has pointed out, if the parts which you have taken from another car were working there, they are unlikely to be part of your problem.
You might also exchange the nozzles; the original ones may very well be completely plugged. Also, loosen the injection lines at the nozzles, run the fuel pump, and press down on the air flow sensor plate. There should be fuel flow from the lines at each nozzle.