Anyone know what the pressure the 2.7 low pressure pump runs at?

[Mountain Man]

Hi JeanLuke,
The only thing that I have done in regards to evactuating air is crank it over. Should I crack an in jector line. I also purchased a hand pump with hose like you would have for an outboard motor, where do I attach it.
Rob

[JeanLuke]

Don't crack an injector line. Use the hand pump on the priming valve that sits on the side of the top cover beside the fuel rail. Best look for a "how to" on YouTube.

Edit: see http://www.ausjeepoffroad.com/forum/....php?p=1640344

[bodgie]

Originally Posted by JeanLuke

What is the fuel pressure when cranking?
With the Jeep Diag Pro you can see these. I can't overstate how much it helps to diagnose.

You can also check the voltage on the output of the fuel pressure sender. Not sure what the correct pin is at the moment but it should be easy to find in the manual. From memory mine is about 1.2 volts when cranking.

Originally Posted by JeanLuke

Having had the system open, what have you done to evacuate the air?

You may need multiple efforts to purge the air out of the system. I'd crack the line myself, but as JL has said this is dangerous.

Try some start ya bastard to fire the engine to speed up the fuel delivery process to the HP pump.

[JeanLuke]

Originally Posted by bodgie

Try some start ya bastard to fire the engine to speed up the fuel delivery process to the HP pump.

That is likely to work if the LP side has a few minor air pockets in it. However if the LP side has been opened and drained back to the tank, the HP pump effectively has no lubrication and won't for quite a time. The LP pump is very bad at pumping air - it's a fuel pump.

Adding SYB to the equation *might* damage the HP pump by running it at operational speed without lubrication. In my opinion, it is much less risky to purge the air using the system provided by the manufacturer.

It may work out okay, but be aware of the risk.

[bodgie]

Originally Posted by JeanLuke

That is likely to work if the LP side has a few minor air pockets in it. However if the LP side has been opened and drained back to the tank, the HP pump effectively has no lubrication and won't for quite a time. The LP pump is very bad at pumping air - it's a fuel pump.

In theory if fuel has been seen in volume at the bleed valve the LP should be delivering fuel to the HP pump. I've had to prime mine a couple of times to get this resolved. From memory MM had installed a priming bulb pump, which i'm assuming is before the filter. I'd pressurise the system with this bulb and then crack the filter bleed screw to make sure fuel is there first. I'd then pop the bleed valve to make sure bubble free fuel is available there too.

Originally Posted by JeanLuke

Adding SYB to the equation *might* damage the HP pump by running it at operational speed without lubrication. In my opinion, it is much less risky to purge the air using the system provided by the manufacturer.

A short squirt should only make if fire for a short period of time if fuel isn't available to the HP pump. I wouldn't expect this to be any worse than cranking the engine for an extended period of time to see if it will start.

If the engine continues to run, fuel is obviously available and hopefully the problem will be resolved.

Bleeding any diesel engine can be a PITA in my experience. Getting air out of the fuel rail so fuel pressure can build is often the biggest challenge in my experience.

Time and patience is required.

Jason

[Mountain Man]

Hi all,
This is where I am up to, I have ordered a new set of fuel lines, a new cam sensor, and 2 new coils for my sl500. Thought I may as well go all out. I shall wait for everything to arrive, fit the fuel lines first, and then the sensor if I have no luck with the new fuel lines. However, if the sensor arrives first I shall change it and try with the new sensor. If all fails, it can sit in the driveway until it rots.

You know, I loved this vehicle, so comfy plenty of power, and cheap to run, but, now I am on the edge of totally hatting it. Never have I come across a vehicle with such a good name as Jeep, utilizing arguably the best brand engine on the planet, yet such a pathetic system for fuelling. One would have to wonder if Mercedes done this on purpose with the sole intension of destroying Jeep in favour of Mercedes ML. THERE IS SIMPLY NO LOGIC HAVING A SYSTEM SUCH AS THIS, NONE AT ALL.
Over and out,
Rob

[JeanLuke]

I assume you mean LP fuel lines?

Not sure where to connect the coils.