Thanks for the info Gale! I did talk to a guy at Atlantic British today and he suggested I try replacing the "Coolant Temp Sensor". The part is only $20 and it's possible that this could be the culprit. He thought it very unlikely I would be getting intermittent failures on either the relays or the fuel pump - indicated they are typically alive or dead not intermittent. Sounds like that may be worth a try.

 

Thought I had this whipped - NOT SO FAST

Replaced Coolant Temp Sensor and vehicle seemed to run ok - (although it always did while in the shop). My son drove the vehicle for a couple of weeks without a problem. Just when I was beginning to breath easier, the Disco stalled while sitting at a traffic light - would not restart. Let it sit for a few hours, it restarted and drove a couple of miles and then began running very rough and stalled again. Let the vehicle sit overnight - vehicle started and ran less than 1/2 mile and began very rough engine - my son was able to "limp" home.

I returned from being out-of-town and tried to start the vehicle - started fine. Let it run for a few minutes and it ran fine so I shut the vehicle off. Returned to the vehicle 15 minutes later and it would not start. Acts like it is not getting fuel.

I have borrowed a fuel pressure tester and will be testing later today. My question: This seems like a strange failure mode for a fuel pump - Has anyone heard of fuel pump issues like these?

Bill

 

When it does this, test for spark. A warmed up Disco that dies, then restarts when cold can many times be the crank position sensor, which makes no sparks when in trouble. Sometimes CKP sesnors that were replaced are not seated properly or have mounting issues.

 

Thanks for the suggestion SB...now the vehicle won't start when cold. No fuel pressure. Smart move would be to check for spark as per SB's suggestion but I don't have an extra plug.
I pulled the fuel pump and there is discoloration on the top plastic part of the pump. Since the vehicle runs intermittently, I'm replacing the pump without trying to run the pump while out of the vehicle. Will report back after pump arrives.
Bill

 

Stick a screw driver in the plug wire and ground the screw driver where you can see the spark.
SB has the answer.

 

Wanted to report back - I tested for spark and I had plenty of spark. Proceeded to pull the fuel pump assembly - (thanks Danny Lee and all of the other posters who made this far easier). I have attached a picture of the pump....

It looks to me a though the pump was getting hot - a hot pump in the gas tank

Replaced just the pump and the strainer - re-installed and the vehicle started right up. I can clearly hear the pump cycling when the ignition is turned on.

This was a very challenging issue since the pump was working intermittently. I appreciate all the assistance!!

 

Perfection!

 

I'm keeping this thread alive as it's likely related.....

After replacing fuel pump, vehicle has been running fine. After about 10 days, I got an engine code (P1496) - "EVAP System Gross Leak". I couldn't smell or see any fuel emanating from the vehicle so I checked the gas cap and re-set the code.

Vehicle ran for several weeks without an error code.....yesterday the check engine light came on and I pulled 2 codes P0130 (O2 Sensor) and P1496 (Evap System Gross Leak).

Vehicle seems to be running OK at present. Any suggestions on where to go first on trouble-shooting these codes?

 

P1496 -EVAP system gross leak detected. Gas cap or check hoses to the charcoal can and to fuel tank. Nothing to do with the MAF.

P0130 - Oxygen Sensor Circuit Malfunction, A bank side, upper sensor. Replace the sensor and at minimum check wiring/connector.