Fuel pump

[Clements1953]

I have a Chimaera, 4.3 lt Rover V8. Some weeks ago I went to start it, it's not been standing too long, so ignition on - I did not hear the 'chug' of the fuel pump - engine cranking ok but not starting. I've since replaced the 2 30A relays, pump primer and ignition, and had the pump off and tested it off of the car and it appears to run ok. Does the relay have the resistor fitted internally, as, when I'm testing the pump off the car the resistor is not connected. Any ideas?, am I missing something fundamental.

[Belle427]

Stinks of an immobiliser fault to me, do you hear or feel the fuel pump relay click with ignition on?

[Clements1953]

Thanks...I can feel a click on 1 of the relays. I've metered the pump live and neutral and get a deflection at ignition on but that fades after a few secs. I've checked fuses - all are good.

[Shed TVR]

Hi Clements,

If it's recieving power for a few seconds with igniton on that would appear correct to me? If you're cranking it and it isn't staying on consistently then there's an issue. Could be worth checking your ignition system is working.

I'm not as knowledgeable as some on here, but what I would do at this stage is to point to point check the fuel pump wiring all the way back to the relay. Could it be that the inertia switch has failed/tripped? Or maybe there is some corrosion at some point in the wiring that is causing high resistance?

Another idea could be to remove the relay, and see that it is getting power for the correct amount of time during priming by putting your meter probes into the socket. This could rule out the immobiliser intefering.

[ChimpOnGas]

Clements1953 said:

Thanks...I can feel a click on 1 of the relays. I've metered the pump live and neutral and get a deflection at ignition on but that fades after a few secs. I've checked fuses - all are good.

The way the system works is as follows:

1. Key on - Pump runs for 2 seconds

2. After 2 seconds the ECU will turn the fuel pump off

3. The ECU will only turn the fuel pump back on when it sees an engine cranking signal

The thing that confuses people is you can hear the fuel pump run when the key is turned to position one, but you'll never hear if its being triggered under cranking simply because its just too damn noisy.

Put a miltimeter on the fuel pump terminals themselves and have the meter in the car when you key on and then go for the crank, the fuel pump circuit on Chims and Griffs is proven to be temperamental, the issue could be one or more of a multitude of potential faults so you mustn't guess or assume, you absolutely must test!

Common faults within the fuel pump circuit include......

1. A blown fuel pump fuse - Sorry to state the obvious but many do overlook this

2. A blown ECU fuse - As the fuel pump is actually controlled by the ECU, the ECU must have power to activate the fuel pump

3. A faulty fuel pump relay

4. A faulty ECU relay - See point 2

5. A poor connection at any connector in the fuel pump circuit - Trace the complete circuit but its worth a quick check of the connector that lurks behind the carpet flap behind the passenger seat

6. A faulty or triggered fuel inertia switch

7. A faulty immobiliser - The imobiliser fault is a common one due to the way TVR wired the Meta system

8. Poor electrical connections at the fuel pump terminals - This is very common due to them being very exposed to the elements

Finally TVR used cable of rather marginal gauge so voltage drops are very common indeed, especially after over 20 years of internal cable corrosion, add in some corroded connectors and the connectors at the fuel pump itself and it all adds up,. Eventually the circuit reaches critical mass and fails, even when it does supply sufficient current to run the fuel pump there is often a significant drop experienced between battery and pump, curing this can deliver all sorts of engine running benefits.

The truth is from new the fuel pump circuit TVR gave our cars was marginal at best, add 20 years of corrosion and TVR's Meta system wiring gaff into the equation and it's really no surprise people suffer lots of issues. The proper solution is to rewire the circuit using fewer corrosion prone connectors, heavier gauge cable, and with the immobiliser taken out of the equation. Later Bosch fuel pumps also replaced the iffy spade connections with the far superior stud type and with a proper rubber caps to protect them from water ingress, this combined with the other improvements I've listed are some of the best things you can do to improve Chimaera reliability.

I hope this helps?

[Steve_D]

May be worth having a read of this thread on the Griff forum.
https://www.pistonheads.com/gassing/topic.asp?h=0&...

Follow the tests on there to get to the root of the problem but also report back here with anything you find.

Steve

[Clements1953]

Hi, I'm now at the check all wiring and connection stage so I could be a while...I'll let you know my findings

[Coefficient]

If you are getting voltage at ignition and the pump runs OK of the car, then it must be the ground circuit, no? Have you tried the inertia switch reset? Rovergauge software is well worth getting for general diagnostics and would allow you to set the pump to continuous running. You would need the cable as well.