Xj40 bad start when hot

[Neil4 (Neil Mitchener)]

Hello all. Interesting reading from chaps with xj40 starting problems.
So…my 1991 xj40 3.2 litre starts okish cold but once hot doesnt. Like the other chaps when hot the eng spins over and over and no start,switch off and restart, the eng fires immediately.
Put a pressure guage on and pressure reads 40 lbs, but drops very quickly.
So as i had a new fuel pump fitted may 2023, which didnt cure the problem, what do you think?
Is there a non original non return valve that can be fitted under bonnett to solve the problem?

Rgds

Neil in uk

[Robin_O_Connor]

This is where I fitted mine.

[Neil4 (Neil Mitchener)]

Ah thanks,Robin.
Is this instead or as well as renewing the valve in the fuel pump?.
What was your reason for fitting one?
Rgds

Neil

[Robin_O_Connor]

Instead of replacing the fuel pump.
I had to try multiple times to start the engine until it was suggested to cycle the ignition key a few time to prime the fuel rail. Once the one way valve was in it cured the hard start, however the previous number of attempts to fire the engine resulted in the Bosch starter grenading the reduction gears, thats when I found out that the 2.9 through to the 4.0 all used an identical starter according to the Bosch website.

[Neil4 (Neil Mitchener)]

Hi Robin.
Interesting about the fitting of non return valve. Was yours an iiside tank pump type, and if so, whete did you put the valve under bonnet?
Also, where did you get your valve from please, and have you a picture,?
What do you mean when u say about the starter, " grenading reduction gears" problem?
Rgds

Neil

[Robin_O_Connor]

@Neil4

Interesting about the fitting of non return valve. Was yours an iiside tank pump type, and if so, whete did you put the valve under bonnet?

Yes intank fuel pump.
Also, where did you get your valve from please, and have you a picture,?
As per the picture, it was placed in the fuel return line after the FPR (Fuel Pressure Regulator) in the engine bay.

What do you mean when u say about the starter, " grenading reduction gears" problem?

There is a reduction gearbox integrated in the starter motor, because of the excessive number of times the starter was being used to get the engine started the planetary gears gave up and broke.

This was at least 10 years ago, probably more, I sourced the NRV from a local supply here in New Zealand.
Here is another shot showing the location.

[Neil4 (Neil Mitchener)]

Many thanks Robin.
Will try mine now.
Rgds

Neil

[Neil4 (Neil Mitchener)]

Hi again Robin.
Just re reading your info about non return valve sited in the return fuel line.
But does that help the poor starting as would thought the non return pipe should be in the feed pipe,?
Be interested to hear your views please.

Rgds

Neil

[exMBman]

NRV is in the supply line that leads to the front of the fuel rail from what I see in the photo.

Has to be an intank pump or Robin would have just replaced the hex shaped NRV that lives atop the external fuel pump.

Grenading gears was from overuse of starter due to excessive crank time because of non functioning NRV in pump module in the tank.

Robin has given you great info. Hope I clarified it further. Thanks

[Neil4 (Neil Mitchener)]

Ah thanks for that. Which makes sense, but he did write saying its in the return pipe in his reply to me earlier.
Rgds
Neil

[Robin_O_Connor]

It was a long time ago I just know it was placed in a line and it worked

[Neil4 (Neil Mitchener)]

Ah understand Robin.
You been most helpful thank you.
Rgds

Neil

[Neil4 (Neil Mitchener)]

Good morning.
Can anyone tell me the thread size and type where the brass fitting is where inlet fuel line joins the fuel rail on a 1991 xj40 3.2 litre under bonnet, just after the diaghram?
Thank you
Neil