Hi all. Having replaced the poorly engine in my long-dormant L-reg Cinq with a healthier 899cc unit, it's been connected to a (brand new) battery for the first time in probably about a year now. With the ignition on, there is no noise from the fuel pump itself, but the fuel pump relay under the bonnet chatters constantly with the injector warning light on the dash flickering in sympathy. Removing the plug from the pump I get a reading of 9.2v. Is it likely that the pump is seized- and would that cause the relay to chatter like it does? It stops when the plug is removed from the pump.
Technical Cinq fuel pump relay chattering
- Thread starter Steve70
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Technical Cinq fuel pump relay chattering
Hello,
I'd start by cleaning the fuel lines and fuel tank
To be sure if it's the pump, remove the inlet fuel line from the tank on the pump side, put another line in a jar with clean fuel, you'll see if it works.
I'd start by cleaning the fuel lines and fuel tank
To be sure if it's the pump, remove the inlet fuel line from the tank on the pump side, put another line in a jar with clean fuel, you'll see if it works.
I think what I will do first is try applying 12v direct to the fuel pump which will establish whether or not it's dead.
I can also check voltages around the fuel pump relay to see if there are any clues there. Assuming the relay isn't faulty, possibly it's not receiving 12v at it's input, which may be the cause of it chattering OR the low 9.2v at the fuel pump could be the result of the chattering contacts. A bit of detective work needed.
I can also check voltages around the fuel pump relay to see if there are any clues there. Assuming the relay isn't faulty, possibly it's not receiving 12v at it's input, which may be the cause of it chattering OR the low 9.2v at the fuel pump could be the result of the chattering contacts. A bit of detective work needed.
Start by cleaning the fuel lines. The car is like 30 years old. And it was standing unused for a year.
It will be a plus on the old pump and on the new one, too. If the old one is dead.
It will be a plus on the old pump and on the new one, too. If the old one is dead.
After a lot of head-scratching, I found the fault. To cut a long story short, tests at the fuel pump relay socket showed the full 12v present when using the body as an earth point for the multimeter, but only around 7.5v when using the socket's own earth return so it's no wonder the relay was chattering. When installing the engine I had omitted to tighten two spade connections on the thermostat housing which are earths for the ECU wiring loom. With those fully nipped up, the relay and fuel pump receive their full voltage work as they should. Big relief!
