LET won't stay running

[Lee H]

Finally decided to sell the Nova and got someone who is pretty certainly going to buy it but it appears after 12 years it doesn't want to leave me.

Car has been off the road some time and started occasionally. Now when I start it it runs fine for 20 seconds or so but then starts reading ultra lean on the wideband and eventually cuts out.

When it starts running lean I am noticing the voltage at the fuel pump is dropping to 6v. Have removed the Clifford wireless immobiliser as I have read read these can cause these symptoms but the problem still persists.

Got no fault codes or ecu light on.

I ran a new live feed from the battery direct to the pump to test and the car still behaves the same so it is nothing to do with the wire between the fuel pump relay and pump. I have also replaced the fuel pump relay with no joy.

Any ideas please?

[Adam]

The injectors run off the red/blue 12v same as the fuel pump so even with 12v to the pump if the relay isn't switching 12v to the injectors then that explains why it still won't run.

Does it always run for the exact same amount of time ? If so then it doesn't sound like some kind of intermittent earth problem or something.

[Lee H]

It always runs for about 20 seconds then struggles. Can keep it running if I hold the throttle but its missing badly. Once it stalls it runs fine again for 20 seconds or so.

[Adam]

Does sound immobiliser related tbh.
But you've removed the immobiliser completely ?

[Jeff16v]

I had an issue with pump pressure at the rail, I manually ran the pump for 60 seconds then bleed rail to see if air is coming out, it turned out to be air getting sucked in on the pipe from the pump clipped to the spare wheel well, on low cars it can wear through, also when my battery wasn't great it didn't generate enough fuel pressure. Battery recharge cured it.

[Lee H]

Does sound immobiliser related tbh.
But you've removed the immobiliser completely ?

Removed the wireless fuel guard so think its just the ignition and starter that's immobilised now by the Clifford.

[Stuart]

If it was the immobiliser then you'd lose the 12v in an instant, not degrading to 6v etc.

Try a different battery and check the alternator is doing its job,

[Kev Turbo]

Shouts alternator to me, Take a measurement of the battery voltage - If it starts dropping rapidly then that's your issue. Be kind to the new owner and throw a new battery / Alternator setup on it ;)

You have ruled out Fuel by running a feed to the pump.

[Lee H]

Fitted a new Bosch alternator a few years ago and a battery a few months ago but not impossible for them to fail I guess. Always disconnect the battery when the car is just sat there as well.

[Kev Turbo]

I have seen alternators fail within weeks / days so do not rule it out.

Get the multi meter out and take a reading this will give you a yey or nay. Watch the paintwork on the firewall / leg if your changing for new owner :)

[Will F]

Does sound like relay though, did you swap it for a new one or at least a known working one? They are a nightmare!

[Lee H]

Was a spare one I found in the garage. Will see if I can borrow a known good one.

[Lee H]

Had another go at the car tonight and found the following.

Battery is about 12.5v when car off, 14.4v when car running. Got 14.4v at the fuel pump wire at the relay point. At the pump terminal though there is only 2.5v so the car will barely run.

Sounding like a knackered pump or a knackered earth to the pump?

[Will F]

Pump or relay. Pumps hate being left especially if its a standard one.

[Lee H]

Relay must be ok it its supplying the correct voltage down the pump wire?

Typically it's not standard, it's a Walbro one. Got a standard GSi one I think I can try though somewhere just to test.

[Adam]

I'd start with the pump earth due to the fact it the relay seems OK and still no go with a direct pump 12v. Assuming youre just measuring the voltage straight across the pump plug and not using another earth point for the meter?

[Lee H]

I'm measuring the pump voltage between the positive pump terminal and a chassis earth. If I measure it across the pump earth and positive I get 0v for some reason.

[Southie]

Did you have a fuel filter fitted, how olds the fuel in the tank as it could have syphoned crap from the tank through the pump.

[Adam]

Wouldn't kill the pumps power feed though...

[Southie]

Worth a suggestion though as it may come up in thread search later and worth narrowing down Adam ;)

[Stuart]

Run a nice fat wire from the pump ground to the battery ground. Try again.

[Kev Turbo]

Did you fix it Lee?

[Lee H]

Not yet. New earth to the fuel pump has achieved nothing.

[Kev Turbo]

Is there full fuel pressure @ the rail? Test with the valve on the rail - Should squirt everywhere once the valve is depressed.

[Lee H]

Fuel pressure is low as pump voltage is low. Gauge is saying I only have 2 bar pressure but that is due to the pump not having proper voltage.

[Adam]

Do you get any any V across the pump with the new earth?

[Lee H]

Pump is totally dead now, car won't even start. Got a couple of MR2 pumps here and they show continuity across the two terminals on the pump. The one I have removed from the Nova has no continuity.

Have fitted a Gsi pump I found spare which has continuity across terminals but still won't start, pump is getting red hot but appears to be seized. Time to shell out again on this car it seems, hopefully for the last time though!

[Plug]

Fpr it sounds like to me, as said check if fuel squirts out at the rail,

[Will F]

Could also be a blocked fuel line/return... a mate had the same problem - the pump wpuld run fine for a few seconds then labour - and then stop and get hot....

It turns out that the return pipe had kinked and was blocking the flow from the pump!

[Kev Turbo]

Needs a new Aeroquip Fuel setup and braided lines throughout - Be rude not too ;)