Ignition on no fuel pump
Discussion
dickythediver said:
Embarrassing situation, MOT booked ran the car a couple of days before all good, come to go of for the MOT engine wont start. Everything else seems to work except no fuel pump. Alarm locks and unlocks ok. Stuck for ideas, help.
Had a similar thing recently where a bad batt earth was the culpit. The Three D Mucketeer said:
Ate least your emission test passed with a ZERO reading .... Sorry my sense of humour 
Rover V8s are simples , according to some peeps
.
They are. TVR electrics however, are renowned for bad earth connections. Not to mention super heated fuses and relays right next to said simple V8 in a footwell with heater pipes and perhaps some damp...Rover V8s are simples , according to some peeps
.Check your fuel pump connections first, they do corrode and work loose too, a basic check of the fuses and inertia switch too under the glove flap.
The fuel pump relay is another culprit.
If that looks ok you need to get yourself a test light and test at the pump and work backwards as there are a few problems that could cause it such as the immoibiliser.
The fuel pump relay is another culprit.
If that looks ok you need to get yourself a test light and test at the pump and work backwards as there are a few problems that could cause it such as the immoibiliser.
Hi guys, thanks for all your suggestions. Have tried them all but unfortunately nothing seems to have worked. I swapped the relays over as they are both the same, that did not work, found the inertia switch which had a large rubber end on it pressed that in and there was a click so thought was it but still nothing, fuses all good. might try direct link battery to pump and see if at least the pump is good. Will keep trying but running out of ideas.
Swapping the relays over won't work as one powers the ECU and one powers the fuel pump, the fuel pump still won't work if the ECU has no power. Just jump the pins with a bit of wire on both of them and then you know if it's the relays or not.
You really need a multimeter, have you got one?
If I remember correctly the immobilizer is in the line to the switching power for the relays so you need to jump the relay plug for the fuel pump to check that the wiring from the plug to the fuel pump and that the fuel pump works. If that makes the fuel pump work you then stick a multimeter on that relay switch power and that wire runs through the inertia switch to the immobilizer.
Years since I pulled the original immobilizer out so I might be getting them in the wrong order.
You really need a multimeter, have you got one?
If I remember correctly the immobilizer is in the line to the switching power for the relays so you need to jump the relay plug for the fuel pump to check that the wiring from the plug to the fuel pump and that the fuel pump works. If that makes the fuel pump work you then stick a multimeter on that relay switch power and that wire runs through the inertia switch to the immobilizer.
Years since I pulled the original immobilizer out so I might be getting them in the wrong order.
Edited by s p a c e m a n on Sunday 4th August 11:15
BritishTvr450 said:
Does it turn over on the starter?
If so I’d firstly put a multi meter on the connections at the fuel pump when you try to prime pump. It should read 12.5v for a few seconds.
If not suspect immobiliser or relay issue.
If it does it’s likely the pump has failed.
This. By far the best advice so far.If so I’d firstly put a multi meter on the connections at the fuel pump when you try to prime pump. It should read 12.5v for a few seconds.
If not suspect immobiliser or relay issue.
If it does it’s likely the pump has failed.
Make yourself a test lamp out of an old headlight bulb, something that will carry about 5 amps and load the circuit.
A multimeter although good may show the right voltage on the test but the wiring may not be able to carry the current due to poor connections etc which are common in this circuit.
The connectors live in the door b pillar area where the central locking motors are and can corrode.
A multimeter although good may show the right voltage on the test but the wiring may not be able to carry the current due to poor connections etc which are common in this circuit.
The connectors live in the door b pillar area where the central locking motors are and can corrode.
Belle427 said:
Make yourself a test lamp out of an old headlight bulb, something that will carry about 5 amps and load the circuit.
A multimeter although good may show the right voltage on the test but the wiring may not be able to carry the current due to poor connections etc which are common in this circuit.
The connectors live in the door b pillar area where the central locking motors are and can corrode.
A multimeter although good may show the right voltage on the test but the wiring may not be able to carry the current due to poor connections etc which are common in this circuit.
The connectors live in the door b pillar area where the central locking motors are and can corrode.
What amps are required for the fuel pump, just out of interest?
Start your testing at the fuel pump relay. Remove only this relay.
Identify the following pins:-
30 Purple/white wire
87 (there are 2 of them) you want the one with white/purple & black wires
86 white/green wire.
Test 1
With a piece of wire link 30 to 87. Does the pump run? If it does you have proved the following items are working. Fuse 13, Pump, inertia, one channel of the immobiliser and connecting wires.
Test 2
With the ignition on and the alarm/immobiliser disarmed check for +12V at pin 86. If yes, then you have proved the following items are working. Ignition switch, Fuse 12, another channel of the immobiliser and connecting wires.
Test 3
With 2 jumper wires link pins 30, 87, 87 together and start the car. If it runs, then the relay is the most likely culprit but not complete proof. Replacing it is by far the quickest/cheapest next step.
When sourcing the replacement relay you must get the right type. Most 5 pin relays are ‘change over’ as in they switch the current at pin 30 to different output pins, say 87 or 87a. The type you need has no output when not activated and outputs to 2 pins marked 87 when activated.
If it does not run, then come back and we will check some more options.
Steve
Identify the following pins:-
30 Purple/white wire
87 (there are 2 of them) you want the one with white/purple & black wires
86 white/green wire.
Test 1
With a piece of wire link 30 to 87. Does the pump run? If it does you have proved the following items are working. Fuse 13, Pump, inertia, one channel of the immobiliser and connecting wires.
Test 2
With the ignition on and the alarm/immobiliser disarmed check for +12V at pin 86. If yes, then you have proved the following items are working. Ignition switch, Fuse 12, another channel of the immobiliser and connecting wires.
Test 3
With 2 jumper wires link pins 30, 87, 87 together and start the car. If it runs, then the relay is the most likely culprit but not complete proof. Replacing it is by far the quickest/cheapest next step.
When sourcing the replacement relay you must get the right type. Most 5 pin relays are ‘change over’ as in they switch the current at pin 30 to different output pins, say 87 or 87a. The type you need has no output when not activated and outputs to 2 pins marked 87 when activated.
If it does not run, then come back and we will check some more options.
Steve
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