TVR Bosch Fuel Pump failure.
Bosch type: Type:0.580.464.055
My TVR Griffith 500 had covered around 66,000 miles on its original Bosch fuel pump without incident. To restore the chassis the car was taken off the road for a body lift and remained dormant for about 18 months. When the restoration was complete several gremlins appeared including a non functioning fuel pump no doubt due to lack of use. I had a replacement to get me going but decided to try and identify the cause of the original pump failure.
Applying 12 volt caused the pump to buzz so I concluded it must be seized in some way, applying 24 volt just caused a louder buzz so as it had to be a terminal problem.
I cut open the pump to reveal its components and was quite surprised at my findings.
Thinking that the armature shaft was probably seized in the end case bearings I was interested to see that the armature was not fixed to the stainless steel (SS) shaft but was free to revolve around it, the shaft just being fixed at either end of the case. Looking at the armature apart from the expected commutator wear it looked fine as was the SS shaft, it rotated freely. The carbon brushes were only half worn so were also OK. The Pump assembly consists of a stainless circular centre fixed to the armature by a plastic moulding that locates in the 5 holes, it has 5 slots at its periphery and revolves within a fixed stainless surround, in the slots should be 5 SS cylinders ( one was lost) that are thrown outwards as the centre revolves. As the whole assembly is surrounded by fuel these small cylinders act rather like an oil pump and create a pressure towards the pump outlet. A one way valve on the pump inlet side prevents fuel being returned to the tank.
The reason for the seizure was unexpected but was found to be due to the small SS cylinders stuck between the central assembly and the fixed outer enough to prevent the armature and thus the pump to rotate.
When cars are to be laid up for a considerable time and especially when the fuel has been drained completely perhaps it would be prudent to fill the pump with paraffin or similar to keep the pump mechanism oiled.
for 24 years I have always taken the car off the road during the winter months but fuel has always been present and have never experienced a problem so maybe the absence of any fuel and the long lay up caused the corrosion.
My TVR Griffith 500 had covered around 66,000 miles on its original Bosch fuel pump without incident. To restore the chassis the car was taken off the road for a body lift and remained dormant for about 18 months. When the restoration was complete several gremlins appeared including a non functioning fuel pump no doubt due to lack of use. I had a replacement to get me going but decided to try and identify the cause of the original pump failure.
Applying 12 volt caused the pump to buzz so I concluded it must be seized in some way, applying 24 volt just caused a louder buzz so as it had to be a terminal problem.
I cut open the pump to reveal its components and was quite surprised at my findings.
Thinking that the armature shaft was probably seized in the end case bearings I was interested to see that the armature was not fixed to the stainless steel (SS) shaft but was free to revolve around it, the shaft just being fixed at either end of the case. Looking at the armature apart from the expected commutator wear it looked fine as was the SS shaft, it rotated freely. The carbon brushes were only half worn so were also OK. The Pump assembly consists of a stainless circular centre fixed to the armature by a plastic moulding that locates in the 5 holes, it has 5 slots at its periphery and revolves within a fixed stainless surround, in the slots should be 5 SS cylinders ( one was lost) that are thrown outwards as the centre revolves. As the whole assembly is surrounded by fuel these small cylinders act rather like an oil pump and create a pressure towards the pump outlet. A one way valve on the pump inlet side prevents fuel being returned to the tank.
The reason for the seizure was unexpected but was found to be due to the small SS cylinders stuck between the central assembly and the fixed outer enough to prevent the armature and thus the pump to rotate.
When cars are to be laid up for a considerable time and especially when the fuel has been drained completely perhaps it would be prudent to fill the pump with paraffin or similar to keep the pump mechanism oiled.
for 24 years I have always taken the car off the road during the winter months but fuel has always been present and have never experienced a problem so maybe the absence of any fuel and the long lay up caused the corrosion.
The Pump components
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loosely assembled
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The pump assembly
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Brush Wear
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One -Way valve
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Permanent magnets
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