(1978) 924 2.0 FUEL PUMP RELAY__________ ((( 477 906 059 )))
- Thread starter West-Awake
- Start date
West-Awake
New member
mok924lux said:
Good evening M., no I haven't got sorted as yet, I haven't even had the time as of late. Do you know of someone that may have one?
Regards
Connie
vitesse
Active member
As an aside to this problem,my friend's 1976/7 924 hasn't run with the correct relay,even the replacement ,for more than enough seconds to start the engine which is why last year I fitted a standard relay in the circuit with Lucar connectors plugged into the relay socket,controlled by a separate illuminated switch.
this allows us to get the engine warmed up but still not mot'd as waiting for the loan of a mixture tester to set to the correct figure( sadly my Gastester doesn't work having lent it to someone ).
We decided whilst we wait for this to find out why the relay wasn't working correctly.For those familiar,the top of the airflow housing on this model has a Bosch 2 blade socket called the "switch" in technical write ups.
What is supposed to happen when you start the engine is the throttle plate is lifted by the airflow breaking a contact with this "switch" (until now being earthed out) leaving the circuit it is in -open circuit.
This then switches connects terminal 86 in the relay circuit permanently leaving the fuel pump running.
On testing the continuity of the Bosch socket "switch" we found it earthed out whether the throttle plate was at at the "stopped " engine position or -lifted -.
On stripping the steel "bridge " from the aluminium casing we were baffled until we realised that what had been a rather thin walled hollow spigot on both the black plastic mouldings which is obviously meant to electrically insulate the bridge from the fixing screws had effectively vanished ,hence leaving the Bosch switch continually earthed out.
We fitted a isolating sleeve before Xmas & hopefully tomorrow will refit the AFM & find out whether our "fix " is successful.
this allows us to get the engine warmed up but still not mot'd as waiting for the loan of a mixture tester to set to the correct figure( sadly my Gastester doesn't work having lent it to someone ).
We decided whilst we wait for this to find out why the relay wasn't working correctly.For those familiar,the top of the airflow housing on this model has a Bosch 2 blade socket called the "switch" in technical write ups.
What is supposed to happen when you start the engine is the throttle plate is lifted by the airflow breaking a contact with this "switch" (until now being earthed out) leaving the circuit it is in -open circuit.
This then switches connects terminal 86 in the relay circuit permanently leaving the fuel pump running.
On testing the continuity of the Bosch socket "switch" we found it earthed out whether the throttle plate was at at the "stopped " engine position or -lifted -.
On stripping the steel "bridge " from the aluminium casing we were baffled until we realised that what had been a rather thin walled hollow spigot on both the black plastic mouldings which is obviously meant to electrically insulate the bridge from the fixing screws had effectively vanished ,hence leaving the Bosch switch continually earthed out.
We fitted a isolating sleeve before Xmas & hopefully tomorrow will refit the AFM & find out whether our "fix " is successful.
vitesse
Active member
Further progress report-today as no rain,pushed car out of garage,& started on the switched 4 blade relay until the fan cut in.
Removed the 4 blade relay connections & replaced the fused proper relay in it's base-then restarted the car.
Success-engine started & also continued to run at idle as before so showing that:-
a)There was nothing wrong with the proper relay ( & possibly the one before that James replaced FOC)
b)The act of inserting the insulating sleeve through the black plastic moulding which the steel bridge is clamped to with steel setscrews either side thus replacing the missing plastic location spigot was effective.
c)Given this thin spigot is obscured by the setscrew head & is not therefore possibly missing when given a cursory look could be the reason why other people have starting/running problems with similar age 924's & therefore suspect the relay.
Happy day for us--hopefully Albert Walsh will come up with his proper exhaust gas analyser for next week allowing me to check & set the mixture correctly plus idle speed prior to hopefully a successful MOT.
My only reservation is that I haven't access to the correct fuel pressure gauge & valve to check the fuel distributor so I am hoping that that it's original settings will suffice.
Removed the 4 blade relay connections & replaced the fused proper relay in it's base-then restarted the car.
Success-engine started & also continued to run at idle as before so showing that:-
a)There was nothing wrong with the proper relay ( & possibly the one before that James replaced FOC)
b)The act of inserting the insulating sleeve through the black plastic moulding which the steel bridge is clamped to with steel setscrews either side thus replacing the missing plastic location spigot was effective.
c)Given this thin spigot is obscured by the setscrew head & is not therefore possibly missing when given a cursory look could be the reason why other people have starting/running problems with similar age 924's & therefore suspect the relay.
Happy day for us--hopefully Albert Walsh will come up with his proper exhaust gas analyser for next week allowing me to check & set the mixture correctly plus idle speed prior to hopefully a successful MOT.
My only reservation is that I haven't access to the correct fuel pressure gauge & valve to check the fuel distributor so I am hoping that that it's original settings will suffice.
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