Hello friends,

I made a new thread of my cold start issue ( cranking needed for 10 secs before firing up. )
since it is not related to my cold start injector :
My csv is spraying as it should :

So I suspect my WUR could be the culprit.
I did a cold control pressure measurement : it gave about 0,8 bar (11,6 psi) while ambient temperature was 32 ° Celsius (90° F)….

Is this a correct pressure? According to the WUR heatup diagram, I should have a cold pressure of about 1,6 to 1,8 bar ( 23 - 26 psi) with that high ambient temperature



Does this influence my cold start ?

Once I managed to start the car after cranking for about 10 sec, car is running fine.

 

Here is a picture of my WUR (0 438.140.036 ) where you can see that the pin is driven quite deep by default.
Shouldn't the difference rather be about 1 mm with the top of the case :

 

I measured the cold control pressure and warm control pressure with engine running :
* at the cold start (temperature measured on case of WUR = 18°C (64°F)) : cold control pressure = 1,1 bar (16 PSi) -> WSM spec = 1,3 bar (18 PSi)
* warm control pressure = 3,6 bar (52 PSi) -> WSM spec = 3.,4 bar +/- 0.2 (49 PSi +/- 3 PSi)
* system pressure was 5,6 bar (81 PSi)
* rest pressure
after 10 minutes 3.2 bar (46 PSi)
after 20 minutes 3.1 bar (45 PSi)
after 30 minutes 3.0 bar (43 PSi)
after 60 minutes 2.7 bar (39 PSi)

So these seem to me all correct numbers....yet, starting the car cold with coldstart valve connected provides a hard start

Is there another component that can cause a hard start??

 

Today’s update : the coldstart issue has something to do with priming of fuel pump.

So when starting the engine the next day or even starting it after 6h, the car doesn’t start right away.

But when turning on ignition key , then turning it off and this with sequence of about 5 times, it will directly starts the 6th time !
Any idea where to look for ?

 

Inspect your fuel accumulator. It is attached by a hose after your fuel filter either off of the filter or in the wheel well.

If it fails it can either leak out of the weep hole and/or just lose fuel pressure and cause long cranking and hard starts.

 

But wouldn’t I have issues during warmstart if my fuel accumulator fails?
Strangely enough I do not have a warm start issue. And once the car is started, I do not have long cranking or hard starts…at least not within the first 4 hours when engine did not run.

 

Have you replaced the check valve back by the fuel pump and filter? It's job is to maintain pressure in the system and not have the fuel feed back into the tank.

 

I don’t think it’s the check valve or accumulator since you posted the leak down numbers and they all look fine. Have you gone through all the electrical? Grounds etc? Is it running too lean? Have you gone through the injectors?

 

pump with check valve is renewed this year. The accumulator is new since 2016, so I doubt it is leaking ( I would have noticed any fuel smell or leak on the ground)
Soon I will remove the fuse-relay board since I want to replace the plastic tube fuses by spaded ones.
At the same it is a good idea to verify all connections on the relay board.

 

I discovered somthing else :

when turning ignition on , I sometimes can hear a squeal of the FD building up pressure when pump is activated for a second.
When this occurs, the engine doesn't start directly and I have a hard start.
Here is a movie :

In all other cases there is no sound and I cannot hear my pump as if pressure is immediately built up.
In these cases, engine directly fires up.

Any idea what this squealing sound means ?

 

I have just done a overhaul/restoration of my petrolsystem in the back of the car. I bleeded the fuelpump and connected everything. Cranked for a few seconds to get the pressure up and air out of the lines. Then I turned the key over two times to hear the pump etc. The other time I turned the key, and the pump pressurized it again I heard a very similar "squeek" like yours. Maybe not so loud like yours but very similar. Then just a few cranks more and it fired right up. I have no hard start issues, cold or warm now. So, my sound came from air going out of the system in the CIS etc. Maybe you have some air leaking into the system in the front? Just a thought...

 

Well, the following parts are new : injectors, fuel pump,,fuel filter,fuel accumulator, sparkplugs,ignition cables, rotor
And my FD and WUR have been overhauled completely. System pressure and other measured cold and warm pressures are ok
It is only a hard start when engine is started again after min 6h.
But it doesn’t happen each time, 3 out 10 times the car starts fine …
Is the squealing sound related to my FD or air mixture throttle ?

 

What about the cold start injector, also new? How about the temp sensor that determines when the ground is completed to the cold start injector causing it to fire?

 

Coldstart injector is not new but has been cleaned and tested.
As for the temp sensor, it works within temperature ranges.
What I find strange is that when connecting the blue connector coming from sensor to the coldstart injector, the car has much more difficulty to coldstart.
As if coldstart injector is spraying too much.
But when engine has been driven a while and is hot during the summer and I leave me car sit for about 6h, I encounter the same issue. So in this case it cannot be the
temp sensor since after 6h, the temperature of the cool water is still more than 35° C so it won’t activate the coldstart injector
So I suspect another issue…

 

The squeal sound is the injectors spraying as the fuel pressure hits the fuel distributor and the injectors.
If the injectors spray without cranking, the engine will be flooded.
The next time you hear this sound, go disconnect the cold start valve (so no more fuel is added into the intake), apply full throttle, and see if the engine starts better.

The fuel accumulator keeps this from occurring, normally. (It's the "shock absorber" in the fuel system.)
Anything abnormal about the accumulator? Correct part number? Hooked up correctly?

Your warm-up regulator has the adjustment "pin" very deep into the regulator, as you suspected.
I'd get this pin back to the correct starting depth and then adjust the pin to get the proper fuel control pressures.
You get the control pressure low enough and this will also blow the injectors open when the engine is cold.

The system pressure is reduced by the control pressure. This is what the injectors "see".
So, if you have 5.8 bar of fuel pressure and the control pressure is 1.0 bar, the injectors "see" 4.8 bar of pressure. If you have 5.8 bar of fuel pressure and the control pressure is 2.0 bar, the injectors will "see" 3.8 bar of pressure.
Keep in mind that the fuel pressure at the injector is what makes them spray.
(The above is not exactly what occurs, but close enough, for this discussion.)