Hello,

I have a '79 242. I have replaced the following parts:

• Fuel Pump (tank)
• Cold Start injector
• Fuel Filters

I have fuel in the cold start injector. I have a good spark on ignition, but there is no fuel being delivered to the fuel injectors. There is fuel flowing from the pump to the distributor and return to the tank.

I've narrowed it down to the fuel distributor or the fuel pressure regulator. Has anyone else had similar issues? Before I start to replace, please tell me if you've got any ideas.

-zantegeorge

 

The CIS fuel injection system - you must have at least 65 psi fuel pressure for the injectors to fire. I doubt you have a fuel pressure tester that can connect "teed" into the hose at the top of the fuel distributor so -

Pop/pry injectors up and out of their black plastic holders (hopefully the plastic lines won't break at this age), lay them on the cam cover spraying over the spark plug wires (sounds safe- huh?) turn key on, hot wire fuel pumps with a jumper wire or 2 to run all the time, and push the air metering plate (long screwdriver or bendable tool) from the bottom of the air intake. The injectors should spray (all over the top of the engine). If not your fuel pressure is too low. If yes - fuel distributor and control pressure regulator are probably OK! Or you can do all the other steps and just push up the plate without injector removal - they make a high pitched sound when they are spraying. If they spray - observe the spray pattern - if erratic full volume (plate as high as possible) can clean up the spray pattern.

The fuel distributors NEVER fail. Unless corrosion from old age is creating problem in one or more cylinders. The control pressure regulator (is that what you are calling the fuel pressure regulator?) changes the pressure on the hose going to the top of the fuel distributor. What it does is when the engine is cold the "control pressure" is lower. That allows the metering plate to go higher for a given amount of air - thus delivering more fuel for a cold engine that requires that (like an automatic choke). Sure sometimes I have replaced those - but not for not starting.

Yes, you need to test more BEFORE replacing expensive stuff that is not bad. Any large/or sometimes small air leak (injector seals, vacuum hoses, manifold gasket ) between the intake valves and the fuel metering plate will/can cause "no fuel to the fuel injectors".

Test by pushing the plate up (carefully). then formulate a reasonable diagnostic process that does not involve guess, replace, and be pissed (and poorer) because that did not fix it.

I've got years of knowledge and plenty of ideas - that system was used from 74 140 to the 85 240 turbo. Those systems are easy to fix - once you understand how they work and are able to test control, fuel and rest pressures.

 

Thank you for the response. Since this post, I have:

-replaced the fuel distributor. I realize you stated they rarely fail, but I was very unsure of the condition of the previous oe.
-ensured good fuel supply to the injectors.
-ensured the electronic ignition is working. I have a good spark with new plugs.
-The timing is correct and I have a new timing belt.


The car ran for a couple hours very smoothly. Now, however, I am unable to get the car to start. any other insight you can offer would be appreciated.

-zantegeorge

 

If the injectors are spraying when you hot wire the fuel pump relay and push the plate up when a suitable tool - you have enough fuel pressure for the car to run.

If the car has a oxygen sensor (even if not connected, which would probably be best) there is a frequency valve that buzzes all the time. Mounted next the the air bellows - it modifies the control pressure considerably. Making the mixture too rich or lean if it is not working . There is a relay that goes bad - If the valve is not buzzing it's not working.

How did you adjust the fuel mixture with the new Distributor? Did you make a short 3mm allen wrench?