Help needed : 1969 MFI dual cold start systems clarification !!!

[SFE]

Hello,

Having more and more difficulties to start the engine with this cold weather, I’ve started to try to understand how a cold start works on those tricky 69’s 2.0 liters engine….

According to this document there is 2 systems.



First one : « cold start solenoid » or sometimes called « enrichment solenoid »
Located on the injection pump, supposed to work between -25/+10 °C
Action on the plunger control rack.

Second one : « solenoid valve » or sometimes called also « cold start solenoid »
Located on top of the fuel filter, supposed to work between -10/-30 °C
Send fuel directly in the intake pipes.

Each system having his own calibrated thermo time switch.

So where I live, the coldest temperature being around - 5°C, only the first system should work.
But when I disconnect the fuel filter solenoid hoze, fuel is coming, so my understanding is the second system is working whatever the temperature.

So if the first system is also working (I haven’t checked it yet), the engine might be to rich or flooded, is that possible ?

If the first system is not working, the engine is to lean, is that also possible ?

Thanks for your help !

[edmayo]

To check the enrichment solenoid pull the wire to it and install a test light, crank the engine and see it the light comes on. Then remove the fuel hose from the aircleaner and direct it to a container, crank engine and see if there is fuel in container. If they both are working just pull the wire from the valve on top of the fuel filter and see how the engine starts. If the start is good then leave the wire off of the filter solenoid. These thermal switches are 50 years old, one could be out of tolerance.

[SFE]

To check the enrichment solenoid pull the wire to it and install a test light, crank the engine and see it the light comes on. Then remove the fuel hose from the aircleaner and direct it to a container, crank engine and see if there is fuel in container. If they both are working just pull the wire from the valve on top of the fuel filter and see how the engine starts. If the start is good then leave the wire off of the filter solenoid. These thermal switches are 50 years old, one could be out of tolerance.

Thank you Sir !
I know the fuel is coming from the system on top of the fuel filter when cranking, already tested that.
I will test the solenoid attached to the injection pump with a lamp and report to you !

[SFE]

Well, we found the problem.....the enrichment solenoid was not energized when cranking the engine because the relay was not working.

Fortunately the relay of the horn being the same we had a spare ready to do the job and now the engine is starting right away even with the valve on top of the fuel filter disconnected

Anyone knows if the horn relay in the front trunk energize something else ?

[edmayo]

It only does the horn. Glad to see you fixed it .