XJ40 ( XJ81 ) 1986 - 1994

4.0 Stalling

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Old 01-28-2024, 05:28 AM
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Default 4.0 Stalling

Hello!
I've had a weird stalling issue twice this month, coincidentally at the same intersection a few weeks apart.
So, the first time, I came to a stop and the car stalled, turned it back on and the transmission warning light came on for a few kilometres. That was it, no further problems or strange occurrences for 3 weeks.
Until yesterday. Same situation, I come to a stop. Car stalls. I try to start it but it wont fire up. Cranks just fine. Unplugged and replugged a few sensors. Nothing. CPS was also ok since it showed a few RPM when cranking. I then turned off the radio and so on to have a listen. And there it was, the fuel pump didn't run. Changed the fuel pump relais with the horn relais and the car came back to life.
The horn still works with fuel pump relais installed.
When I came home I tried putting the correct relais in their spot and to my surprise the car works.
How? Was the relais switch just a coincidence and the problem could be something else?
What are your suggestions?
Thanks in advance.
Jan
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Old 01-28-2024, 11:08 AM
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Originally Posted by HerbieOPF
Hello!
I've had a weird stalling issue twice this month, coincidentally at the same intersection a few weeks apart.
So, the first time, I came to a stop and the car stalled, turned it back on and the transmission warning light came on for a few kilometres. That was it, no further problems or strange occurrences for 3 weeks.
Until yesterday. Same situation, I come to a stop. Car stalls. I try to start it but it wont fire up. Cranks just fine. Unplugged and replugged a few sensors. Nothing. CPS was also ok since it showed a few RPM when cranking. I then turned off the radio and so on to have a listen. And there it was, the fuel pump didn't run. Changed the fuel pump relais with the horn relais and the car came back to life.
The horn still works with fuel pump relais installed.
When I came home I tried putting the correct relais in their spot and to my surprise the car works.
How? Was the relais switch just a coincidence and the problem could be something else?
What are your suggestions?
Thanks in advance.
Jan
​​​​​
Hey Jan, I also have a 1992 XJ and had a similar issue. I also switched the relays and the problem disappeared or so I thought. Turns out the fuel pump connector on the evap flange on top of the gas tank was the culprit and a known failure point on these cars. The connector is likely burnt or in the process of failing preventing the fuel pump from getting power. I resolved this thanks to a fix from Don where you remove the connector and drill two holes to run wire directly to the fuel pump and bypass this issue altogether, Ever since I did this, I have not had a stall or no start issue since. Good luck!
 
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Old 01-28-2024, 05:28 PM
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I was thinking that might be the issue too. Thats a "take the tank out" issue which is no fun at all. Definitely do your research there. There are several threads describing removing the hose clips underneath and taking care with the pump housing itself, and the filler neck seal, both these being NLA parts. I had the collapsed tank syndrome and have been "fortunate" enough to remove 3 tanks but only have to install one.
Regards,
 
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Old 01-29-2024, 04:22 PM
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Thanks!
Oh my beloved british electrics. I will have a look at the connectors!
Jan
 
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