Hello all, this is my first post on the forum. I recently purchased a 2004 discovery 4.6 SE7. The truck has a fresh engine rebuild ( resleeved block, decked block/heads, full head job) about $11,000 total in engine/trans rebuild. Less than 1,000 miles on rebuild. Recently it's been starting hard. Cranks totally fine and fast. When it's cold it usually takes 2 cycles of trying to start it to get it to start. When it's warm it takes 4-5 cycles of the key trying to get it to go. Changed crank position sensor today with no change whatsoever. I get no check engine codes and it runs great once started. Where do I go from here? I did have a low voltage code that also set off my m and s lights, but that was after the truck was sitting for months and needed to be jumped. The lights cleared themselves after 20 min of driving and haven't returned. Im very mechanically inclined and a farm diesel mechanic by trade. I'm new to land rovers but not new at wrenching on things.

 

Also when the truck is running, if I shut it off and start it back up imediately it will instantly start back up. Could this be a fuel pump issue?

 

There's a valve in the fuel pump that keeps fuel from draining back into the tank. When it goes bad, you get symptoms like yours. There's a Schrader valve at the back of the engine on the left you can use to check the fuel pressure. If it's zero while the vehicle has been sitting, it's most likely a pump issue.

 

I looked for the shrader valve and can't seem to locate it. Would these pump issues be worse when the engine is hot? Yesterday I replaced the crank sensor, with the the same hard start problem. This morning it fired right up but idled irratic like it was starving for fuel then stalled after about 15 seconds, then I hit the key it fired right up and ran fine. I'm wondering if maybe there's settlement in my tank and its worse when warm because something is plugging up the sock filter on the bottom? I don't want to just throw parts at it but the truck itself has 125,000 miles so maybe it is time for a pump change

 

You can also pull the fuel line at the pump and see if you get sprayed in the face. Really sounds like fuel pressure issues.

Try cycling the key to on, wait for 5 seconds, then turn it off for five second and repeat 3 times to try and prime the system.

 

That's exactly what I've been doing usually between 2-5 cycles of the key and it fires up. I was thinking of that as well on the pulling the fuel line off sending unit. Is there a special tool needed or do I just press in the tabs and pull it back? It seems to have all the classic dying fuel pump symptoms to me, I'm new to land Rover but have had multiple 3rd and 4th gen gm f body cars which are prone to fuel pump failure and normally have the same symptoms. Basically everything online said if the truck doesn't start then it's a crank sensor so that was my first thought.

 

If you turn it to on but don't try to start it, the ECU will turn the fuel pump on for about 3 seconds to prime the system. It will either do this 2 or 3 times before disabling the function until you crank the engine. If it works, it puts less wear on the engine than trying to crank it repeatedly.

Pulling the fuel line is just two tabs, as you've said. The hardest part is getting the carpet up, which isn't really that hard.

 

Yes that is what I do, just turn the key to the on position until the chime stops and repeat 3-5 times and it starts. Runs rough than smoothes out after a couple seconds as if it has to get fuel to all injectors. I don't want to just throw parts at it but may just bite the bullet and get the pump. Couldn't hurt to have a new one anyway.

 

Well I pulled up the carpet to take a look. I'd say with 99% certainty it appears to be the original pump. Now for the next problem, I can not get the lock ring that holds the sending unit in to turn for the life of me. Tried using heavy screwdriver and hammer to turn it but tabs just break. What do I do now?

 

If it's rusted and started to swell into the threading, you're going to have to break it and replace it. I used a pry bar and peeled the sides away from the threads. Did you check to see if there was pressure in the fuel lines?