Fuel pump not priming after changing ignition switch
Discussion
Hi all,
My first tvr post. I have a 96 chimaera 400 owned for the past 2 and a ½ years with no trouble, until I had a go at replacing the ignition switch… whilst I change the oil, filters and other bits like that, this was my first go at doing anything with the electrics.
Issue 1 - I replaced the ignition switch, went to start the car, but the fuel pump wouldn’t prime when pressing the meta fob. The engine would turn over but obviously wouldn’t start.
Issue 2 - I then thought I’d put the old ignition switch back on to see if that resolved the problem, but in removing the new one I accidently made contact with the terminals on the ignition feed with my screwdriver, with the battery still connected, a spark later and nothing was happening at all.
The 80 amp strip fuse behind the battery, the 100amp strip fuse near the oil filter and the 25amp battery feed to the ignition were all fried. These have now been replaced and I am now back at Issue 1 with the fuel pump not priming.
I have spare relays and have tried replacing the fuel pump relay, but that made no difference.
I’d really appreciate anyone’s thoughts or suggestions on where to go from here?!
I have seen on other posts, the offer of instructions to bypass the immobiliser, would anyone have these instructions available to send me please?
If I cant solve this, I’m down near Christchurch, Dorset if anyone has a local recommendation for someone that could help?
Many thanks in advance.
Cheers
My first tvr post. I have a 96 chimaera 400 owned for the past 2 and a ½ years with no trouble, until I had a go at replacing the ignition switch… whilst I change the oil, filters and other bits like that, this was my first go at doing anything with the electrics.
Issue 1 - I replaced the ignition switch, went to start the car, but the fuel pump wouldn’t prime when pressing the meta fob. The engine would turn over but obviously wouldn’t start.
Issue 2 - I then thought I’d put the old ignition switch back on to see if that resolved the problem, but in removing the new one I accidently made contact with the terminals on the ignition feed with my screwdriver, with the battery still connected, a spark later and nothing was happening at all.
The 80 amp strip fuse behind the battery, the 100amp strip fuse near the oil filter and the 25amp battery feed to the ignition were all fried. These have now been replaced and I am now back at Issue 1 with the fuel pump not priming.
I have spare relays and have tried replacing the fuel pump relay, but that made no difference.
I’d really appreciate anyone’s thoughts or suggestions on where to go from here?!
I have seen on other posts, the offer of instructions to bypass the immobiliser, would anyone have these instructions available to send me please?
If I cant solve this, I’m down near Christchurch, Dorset if anyone has a local recommendation for someone that could help?
Many thanks in advance.
Cheers
Hi, first thing, always disconnect the battery when doing wiring. Saves any issues with shorting.
Why did you change the ignition switch? Just for background.
The ignition switch is very simply wired, just three. Power in, ignition supply and starter supply. When you turn the key to 'on' are the normal things happening? Lights on dash etc? The obvious fault with the ign switch would be that you are not getting power to the ignition wire.
You are best to check with a multimeter. From memory you have white, a red and a white with red stripe wire. White with red stripe is the starter wire. When switched on both the red and white wires should have 12v. Use the steering column for earth.
If there is power, the fault is not with the ignition switch.
That’s a start. You are then into finding why the fuel pump isn’t powered.
Best
Nic
Why did you change the ignition switch? Just for background.
The ignition switch is very simply wired, just three. Power in, ignition supply and starter supply. When you turn the key to 'on' are the normal things happening? Lights on dash etc? The obvious fault with the ign switch would be that you are not getting power to the ignition wire.
You are best to check with a multimeter. From memory you have white, a red and a white with red stripe wire. White with red stripe is the starter wire. When switched on both the red and white wires should have 12v. Use the steering column for earth.
If there is power, the fault is not with the ignition switch.
That’s a start. You are then into finding why the fuel pump isn’t powered.
Best
Nic
Just had a look and the alarm has 2 15 amp fuses on it, I can't remember how it's all wired or what they're for as I've bypassed my immobiliser but you might be in luck and it's one of them.
I'd start by pulling out the fuel relay and jumping the pins on the plug though and then try to start the car to see if the ECU relay is working.
Hi all,
Thanks for your help.
- for background the reason for replacing the ignition switch was because i have had say 5 occasions in 2 1/2 years where i have gone to start the car from cold and nothing happens at all. I have had a garage check that the factory error with the wiring has been corrected, which it has. A garage i use said the issue is likely either ignition switch fault, wiring fault or starter motor fault, so I am starting to work through these, the ignition switch being the first i've tried. Thoughts welcome on this;
Responses to the various points:
- i replaced both relays in spagetti and that didnt solve it;
- NicB - i have checked with a multimeter and the white wire and red wire both have 12.8volts. i've hopefully attached a photo
- when i turn the key, lights turn on the dash and i hear the clicking of relays
- fuses on alarm, i don't know where the alarm is, could someone advise please?
- i've checked the fuel cut off under passenger dash/cubbyhole and this is still pushed in;
- spaceman suggestion of jumping pins on the plug- i think this is beyond my pay grade/i'm not quite sure what you mean/how to do that. could you elaborate please?
Any further thoughts on diagnosing?
Thanks again.
Thanks for your help.
- for background the reason for replacing the ignition switch was because i have had say 5 occasions in 2 1/2 years where i have gone to start the car from cold and nothing happens at all. I have had a garage check that the factory error with the wiring has been corrected, which it has. A garage i use said the issue is likely either ignition switch fault, wiring fault or starter motor fault, so I am starting to work through these, the ignition switch being the first i've tried. Thoughts welcome on this;
Responses to the various points:
- i replaced both relays in spagetti and that didnt solve it;
- NicB - i have checked with a multimeter and the white wire and red wire both have 12.8volts. i've hopefully attached a photo
- when i turn the key, lights turn on the dash and i hear the clicking of relays
- fuses on alarm, i don't know where the alarm is, could someone advise please?
- i've checked the fuel cut off under passenger dash/cubbyhole and this is still pushed in;
- spaceman suggestion of jumping pins on the plug- i think this is beyond my pay grade/i'm not quite sure what you mean/how to do that. could you elaborate please?
Any further thoughts on diagnosing?
Thanks again.
Check the connection at the starter motor solenoid terminal.
It should be nice and tight and fairly clean, some work loose over time leading to a poor connection.
When the fault occurs you would need to use a test lamp at this terminal just to see if its receiving 12 volts on cranking.
Make sure your battery conditions are tight too.
It does to me stink of an immobiliser fault though.
It should be nice and tight and fairly clean, some work loose over time leading to a poor connection.
When the fault occurs you would need to use a test lamp at this terminal just to see if its receiving 12 volts on cranking.
Make sure your battery conditions are tight too.
It does to me stink of an immobiliser fault though.
Just to make sure, because you've been chasing a previous problem, when you try to start the car at the moment the starter motor spins but there is no fuel pump?
Had to go look because I couldn't remember the colours..
If it's just your fuel pump not priming and not that the starter motor isn't spinning go to the relay cluster in the passenger footwell and find the blue plug, with the ignition turned on and the immobiliser turned off stick a bit of wire (speaker cable/cut extension cable/paperclip) in the back of the two purple and white wires to connect them together. This is connecting pin 30 and 87 together and should make your fuel pump run.
If it is then running try to start the car. If the car doesn't start (starter motor spinning and fuel pump running but not starting) then either try another relay in the ECU (which I think is the black plug) or jump pin 30 and 87 on that one too.
As a side note you should be able to feel both of those relays click if you hold them and turn the ignition on with the immobiliser disengaged.
Had to go look because I couldn't remember the colours..
If it's just your fuel pump not priming and not that the starter motor isn't spinning go to the relay cluster in the passenger footwell and find the blue plug, with the ignition turned on and the immobiliser turned off stick a bit of wire (speaker cable/cut extension cable/paperclip) in the back of the two purple and white wires to connect them together. This is connecting pin 30 and 87 together and should make your fuel pump run.
If it is then running try to start the car. If the car doesn't start (starter motor spinning and fuel pump running but not starting) then either try another relay in the ECU (which I think is the black plug) or jump pin 30 and 87 on that one too.
As a side note you should be able to feel both of those relays click if you hold them and turn the ignition on with the immobiliser disengaged.
Edited by s p a c e m a n on Saturday 8th April 10:56
Hi all,
Update as follows
- 12.5v power to the fuel pump relay socket
- spaceman I do feel both relays clicking when I turn the key,
- fuel pump- pulled cable off pump, tested that end of cable and NO power registering
- not sure if this is relevant but 100amp fuse near oil filter registering circa 6v.
That's all I had time for today!
I will check starter motor suggestions tomorrow.
Happy Easter all.
Update as follows
- 12.5v power to the fuel pump relay socket
- spaceman I do feel both relays clicking when I turn the key,
- fuel pump- pulled cable off pump, tested that end of cable and NO power registering
- not sure if this is relevant but 100amp fuse near oil filter registering circa 6v.
That's all I had time for today!
I will check starter motor suggestions tomorrow.
Happy Easter all.
To point out the obvious, you'll only get power at the fuel pump for the 3 seconds after you've turned the ignition on. I'm trying to remember how it's wired but I think that the fuse by the oil filter is fed from a cable that goes over the gearbox and straight onto the battery live, so check the battery connections if you're only getting 6v there
As stated the 100a fuse is in line from the alternator to the battery as it’s the charging cable and should have around 12.6v so I would check thst again as well as battery voltage and connections for each place you measure try it a few times so you can see the difference between when it works and when it doesn’t
So when you turn the ignition on you should have both relays in the footwell energise but the fuel pump one is controlled from the ecu and only runs for 2 or 3 seconds and then de energised until the engine starts, then it will stay on, but the fuse near the oil filter should always have 12v plus, maybe check that you are using a good earth on your multimeter as maybe you’re just getting a bad reading rather than a low voltage
Good luck
So when you turn the ignition on you should have both relays in the footwell energise but the fuel pump one is controlled from the ecu and only runs for 2 or 3 seconds and then de energised until the engine starts, then it will stay on, but the fuse near the oil filter should always have 12v plus, maybe check that you are using a good earth on your multimeter as maybe you’re just getting a bad reading rather than a low voltage
Good luck
Hi all,
After fiddling around the car did start and I took it to my local garage. They have identified a bad connection at the ignition switch, the cable that has been added for the immobiliser bypass, which they have resoldered and so far so good!
I know my way around my tvr a lot more now than I did a few weeks ago, so thanks for your help with that
Cheers
After fiddling around the car did start and I took it to my local garage. They have identified a bad connection at the ignition switch, the cable that has been added for the immobiliser bypass, which they have resoldered and so far so good!
I know my way around my tvr a lot more now than I did a few weeks ago, so thanks for your help with that
Cheers
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