I have a 1987 xj6. It was running beautifully for the last year. Then, the cold start injector failed and was leaking. After I replaced it, the car has been running rich to the extent that it stalls. At speed it does. It stumble, but the exhaust is dark and the plugs foul in a matter of minutes. It seemed that the injectors were also pouring fuel into the motor (open) at all times. Here is what I have done to trouble shoot:

replaced:
All 6 injectors
MAF
ECU
coolant temp sensor (3rd on rail)
fuel pressure regulator
exhaust o2 sensor
cold start injectors
plugs

checked timing
bypasses fuel temp sensor

so far I am stumped. I’ve read so many posts so am open to any ideas. Perhaps it’s not in the injection system?

thanks! Robbo

 

Meant to say “at speed it runs fine and does not stumble.”

]I have a 1987 xj6. It was running beautifully for the last year. Then, the cold start injector failed and was leaking. After I replaced it, the car has been running rich to the extent that it stalls. At speed it doesn’t stumble, runs fine, I stop - car stops. The exhaust is dark and the plugs foul in a matter of minutes. It seemed that the injectors were also pouring fuel into the motor (open) at all times. Here is what I have done to trouble shoot:

replaced:
All 6 injectors
MAF
ECU
coolant temp sensor (3rd on rail)
fuel pressure regulator
exhaust o2 sensor
cold start injectors
plugs

checked timing
bypasses fuel temp sensor

so far I am stumped. I’ve read so many posts so am open to any ideas. Perhaps it’s not in the injection system?

thanks! Robbo[/QUOTE]

 

Well, you've covered a lot of ground :-)

Good that you replace the coolant temp sensor but what's the condition of the plug-in? Check carefully.

Just for the heck of it unplug the cold start injector. It's a stretch...but maybe it is staying energized.

Also for heck of it check/clean/tighten the bundle of ground wires at the rear of the water rail.

Meanwhile, I'll mull.

Cheers
DD

 

Presumably you are talking about a Series III XJ6, yes?

"1987" was a crossover year from the Series III and the later "XJ40" type XJ6

Cheers
DD

 

Thought this Spark Plug Visual Guide might be of interest:

https://tech.bareasschoppers.com/res...-visual-gauge/

 

Yes a series iii. I will check the plug-in connectors on the coolant temp sensor and ground wires as Doug suggests. This one has me a bit stumped.

 

 

so I changed the thermotime switch and disconnected the cold start injector...no luck. Going to check the fuel pressure next and if not the problem, tear into the air intake and throttle body. Continue to be baffled!

 

Update - an adjustment and cleaning of throttle body has it idling albeit rich but running. Updated symptom - When I was cleaning the throttle body, there was fuel in the base of it. So - I suspect I will need to get a good check of the fuel pressure. Any other ideas?

 

One very basic one. it lead me astray!!

Dirty air filter element. !!!!

Carl

 

leaking injector/s !!!

 

I had replaced all of the injectors when this all started...also replaced air filter. Curious if leaky injectors would occur.

The pressure is 38psi (not running- I activated the pump with maf flap opened)

38 does not seem excessive. So, not sure where to go next.