Posting here as WaltNYC suggested I might get more help here than in general tech.

Current situation: I've had to put my 98 Disco back into full time service, as my son is using my daily driver until his car is fixed.

The Disco will run hot (the dash gauge starts climbing) when going up a hill or when running the AC. The electric fan is working. Turning on the heater helps with this.

If I don't run the air, all is well as long as I"m moving. I just completed a highway trip of 200 miles with no problem. However, if it is allowed to idle for a while and I turn the car off, it WILL NOT START until it cools off. It turns over, just never hits.

I have a code 0340.

I have replaced:
Camshaft position sensor
Crankshaft position sensor
Fuel Temperature Sensor

I also tried insulating the crankshaft position sensor wire, as I read that can sometimes cause issues. No luck. Today I ran to the store, shut the engine off, drove home, then 10 minutes later tried to start it up...it DID start but shook and shuddered for 30 seconds before dying and not wanting to restart.

At this point, I honestly don't care to start throwing parts at it, I'm just curious as to WHICH parts to start with. I am going to try to rig up a spark plug bypass jumper today so that I can see if I get spark when this happens.

No spark = coil?

Spark = fuel pump, fuel pump relay?

Thanks, I need to go have a beer.

 

Have you tried squirting cool water on the crankshaft position sensor cover?

 

Holy moly Walt, mine doesn't have a heat shield...I didn't know it should!! I guess that might be my issue!! is there a part number for that shield for a 98? I'm looking but can't find it.

I am going to try the water trick shortly, i'll let you know.

 

Send an email to Paul Grant. He disassembles these trucks for parts and is super knowledgeable and reliable.

Paulgrant@mac.com

 

Thanks, I sent him an email

More information...

As a stop gap try yesterday, I got some titanium exhaust wrap and wrapped the pipe next to where the crankshaft sensor is to try and keep some heat off it. I drove the truck for about 50 miles, cut the engine off and let it sit for a few minutes. It started back up!! Yay!!! Or so I thought. About 10 more minutes went by and I got in to go to the store. It started...but barely...it sat there and putted for about 2 or 3 minutes, but didn't die...then it kinda straightened out a bit...and I was able to go to the store.

I'll keep working toward the crankshaft sensor issue...but I'm wondering if it might be fuel related instead? If the sensor was hot enough to cause problems on the restart, why would letting it run a couple minutes cool it or let it start working?

Ugg.

Thanks

 

You can check for fuel pressure at the schrader valve on the passenger side fuel rail. should be mid 30's while running.

 

Ok, update...

I rented a fuel pressure gauge kit yesterday and drove home and hooked it up with the engine hot. I checked the pressure....15lbs...after about 2 or 3 min it went down to around 10lbs...I started the truck and it hovered around 12-14 lbs.

Soooo....I've ordered a new fuel pump since RAVE says 2-2.5 bar pressure is normal.

Could this be the hot start problem? I'm guessing the fuel pressure being low is causing the fuel to vaporize in the rail on a hot engine?

Mark

 

Yes. Most likely you only need the pump, not the entire housing. Look for “Airtex e3270” or something close to that on eBay. Should be less than $50

 

If you keep getting P0340 fault codes = it's either wiring or sensor related (cover needs to be in place). If you aren't getting P0340's anymore I would certainly replace the fuel pump, and fuel filter, check PSI at idle, make sure the fuel regulator vacuum line is in good condition.

It is hot enough for heat soak to become an issue. I have never really experienced it with a LR, but when I owned Jeep's with the 4.0L I6 it was very common to have rough starts after running it and then turning it off and trying to restart say 10-15min later.

 

Thanks so much for the information!!

Yes, I am still getting the P0340 code, but think it might not be related to the hot start problem....not sure, suppose I'll find out when I get the pump fixed.

Also, I think I confirmed that my fuel pump is indeed going out, as if the 10-15 lbs of pressure it registered on the gauge wasn't enough! Today I drove it quite a bit and let the gas tank get down to about 1/4 of a tank...it REALLY struggled to run and when I pressed on the gas it just didn't want to go at all....filled up the tank and it was much better...could the weight of the fuel be "helping" out the bad fuel pump?