Mondial 8 weird start issue -- relay related

The AAV won't stop the motor from starting. Although I have had an AAV hose come loose, which caused a vacuum leak. Not easily visible in that location.

A good place to begin troubleshooting is to get a can of starting fluid. With the motor turned off, press the air vane down and spray some starting fluid into the air intake of the FD. The car should not only start, but keep running as long as you keep spraying starting fluid in there. If the car won't start with starting fluid, you probably have an ignition problem. Check the plugs as previously stated, and also check the resistance of the plug wires, they do go bad.

I don't believe the steel injectors will ever go bad, but they do get dirty. I clean the injectors by pulling them out, and soaking them in carb cleaner. There is a small filter screen inside the injectors. This can get clogged, especially if old fuel has dried out of there. Also clean around the poppet valve. Pull the valve down with your fingernails to clean that area of gum.

With the ignition key in the run position, you should be able to press the air vane down causing the fuel pump to energize. You can also hear the injectors spraying fluid. They make sort of a screeching noise. Careful, as this will flood the motor, and you need to give it a few minutes to dry out. If you have spare injectors, you could remove the hats, and attach the new injectors outside of the motor. Place them in clear plastic bottles to catch the fuel. This will show you if the fuel system is working.

 

The cold start injector adds fuel while the starter motor is turning. If she's firing then, sounds like you have a lean condition, most likely a vacuum leak, although it is possible that all of the injectors are clogged. If there is pressure at the air vane, the fuel pump is probably working okay. In my experience the pumps either work, or don't work at all. Try pressing slightly on the air vane while a helper turns over the engine. It might start that way.

Here's some cheap components to help remove the injectors. I usually only use the coupling nut with a little pry bar. Don't try to pry out the injectors directly.

 

How much are you pressing on the air vane ? Press it all the way down. Fuel should spray out of the injectors.

 

Well that's a problem.

Could be a fuel pump. Or could be the FD - plunger not aligned properly, slits clogged, fuel passages clogged ?

Cheap gauge kit here. This will show you system, and control pressure. If system pressure is correct, the fuel pump is good.


https://www.ebay.com/p/Tool-Aid-33865/672824579?iid=231576748949&chn=ps

 

I believe that the cold start injector is at system pressure, whereas the individual cylinder injectors are at control pressure. The difference is the WUR. Are you sure the WUR is not clogged ? You have to take it apart to get cleaner sprayed through those screens.

 

There is a layer of many screens in there. If you remove the WUR and spray cleaner into the input port, I'll bet there won't be any cleaner coming out of the output port. However, if you disassemble it, and remove the little diaphragm, you will be able to spray cleaner through it. This is a more thorough cleaning process.

Also, I'm wondering if your new injectors are the exact same as the originals. It might be worth a try to pull an original injector out to see if that one will spray.

If the injectors are indeed not spraying fuel, the car should start and run with a can of starting fluid.

 

I was thinking about this, and I don't think the WUR is going to cause this problem. Because when you press the air vane down manually, you are bypassing the WUR control pressure.

Try this test if you like. There is a fuel line junction on the starboard side close to the bodywork, right under the engine cover. Remove the fuel line that goes to the FD input. Attach a rubber hose to the other (threaded) end with a hose clamp. Attach an injector to the other end of the rubber hose with a clamp. Put the injector in a bottle, turn ignition key to run, then press down on the air vane. The injector should spray fuel. If not, you've got a fuel filter, accumulator, or fuel pump failure.

 

You are understanding correctly.

There is an inlet filter on the FD. You can try cleaning that.



Also, this regulator inside the FD is what sets the system pressure, by feeding some fuel back to the tank. The return line is the one next to the inlet line. In this video, a tech is adjusting system pressure with shims. You might want to take this out, and have a look at it.



You can also try running fuel through the FD to clean it. Remove the hats on the forward bank as well. These lines can then easily be moved to the back of the motor. Put all 8 hats in bottles, put some injector cleaner in the fuel tank, turn the ignition key to run, press down on the air vane.

And post your question in the 308/328 forum as well. You might find some good tips there.

 

I would try and avoid taking the FD apart. At least wait until you get your gauge kit. The gauge will show you exactly where the problem is. The pump is capable of producing around 120 PSI. The system pressure regulator reduces this to around 75 PSI. This is that little spring/plunger device that allows some fuel back to the tank through the fuel return line. The cold control pressure is around 40 PSI.

I can't help thinking that the sound of "running water" when the pump is turned off is caused by a leaky accumulator, leaking fuel back into the tank. It is the job of the accumulator to maintain pressure in the system for quicker hot starts.

Another thing you can check for is that the voltage to the fuel pump is correct. It needs to be 11.5V minimum. These cars are known for having electrical power supply problems to the fuel pump.

 

We have suggested all the possible ways to find your problem. I think its time to start from scratch :
- empty and clean fuel tanks (dont use that fuel again in this car) ;
- clean fuel filter inside tank ;
- clean and test fuel pump + voltage ;
- clean New fuel filter purging backwards;
- check accumulator holding pressure ;
- test quantity fuel delivery after FD to tanks (1 lt pro 30 sec) ;
from here on follow WM from page D24 to D60.
I think this will be the only way to find exactly what happens.
Guido

 

Good plan,
maybe also see this video how to tackle this :
Its mercedes but the same principles.
FD rebuild : you have to open first to find out what membrame it has...only then you can order a new kit. Watch as many videos as possible so you are confident enough to do this. My motto is : "If someone can do this, I can to !"
Do you have a workshop manual ? if not get one !
That car run before, so it will run again....we all went trough this.
Guido

 

An other inntresting video fuel tank cleaning ;

 

I am still puzzled as to why the injector will spray when connected to the fuel pump output, but won't spray coming out of the FD.

Try this test if you like. Instead of removing the input line at that fuel line junction, remove the return line. Place that in a bottle, then try the injector spray test from the FD. I'm wondering if the system pressure regulator is sending all the fuel back to the tank, and not holding enough pressure to spray the injectors connected to the FD.

 

Primairy pressure regulator stuck in open position. ?!

Image Unavailable, Please Login

 

Could be stuck, or the O rings could be worn, allowing fuel past. Can't maintain pressure. One of the other fuel injectors could be stuck open as well.