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P38 Owner

New Member

• Apr 2, 2007

• #1

Hi all,

Hopefully some one will have some ideas on this one.

My rangie (4.0, Auto non gas. on gems) has on a few occasions become a nightmare to try and start when hot. You tern the key and it fires into life but then stalls. when you try and restart her, she does the same thing. but if you leave it for 10 mins or so and try it, its fine fires straight up on all 8 no problems.

This has only just started to happen and was after a few pointers.

My suspicion is when the key is turned it is catching but then stalls. and in the process flooding the engine? and in leaving it for 10 mins it is enough to let the cylinders vent. but why would this only happen when she's hot?

Am I looking at a sensor problem of some sort?. I have plugged it into auto logic and it hasn't logged any faults.


If anyone has any ideas or suggestions it would be appreciated.

Thanks

Bryan

 

njh

New Member

• Apr 2, 2007

• #2

Hi Bryan.

Does it smell of petrol?, does it run well once its started? What happens if you dont touch the throttle and just keep cranking. Are all the little electrickery's tight and the cables secure for the throttle?

Cheers, Nick.

 

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P38 Owner

New Member

• Apr 3, 2007

• #3

Hi Nick

She doesn't smell of fuel, and once fired its spot no missing or hesitations. with brilliant throttle response.

I dont touch the throttle on starting anyway, but if I keep cranking it it just terns over and over and over. with no etempt to fire.

Bryan

 

njh

New Member

• Apr 3, 2007

• #4

Having a think!

 

T

TimoV

New Member

• Apr 3, 2007

• #5

Could it be that the connector of crankshaft position sensor is loose - or the sensor itself is faulty? If I understand correctly this sensor tells the GEMS ECU what speed the engine is turning. If there's no signal - no fuel nor spark.

I have had similar problems with hotwire (and flapper)-type injection systems, in which the same information comes from the negative terminal of coil.

EDIT: I checked the workshop manual. It should go to limp-mode when this sensor fails - so it is not the probable cause. I'm not familiar with the gems system though. However, engine coolant temp sensor could explain hot starting issues. If it fails the ECU thinks that the engine is cold and makes the car run extremely rich or fail to start completely when hot (at least on RRC:s). It could be the connector also.

 

rick071155

New Member

• Apr 3, 2007

• #6

TimoV said:

Could it be that the connector of crankshaft position sensor is loose - or the sensor itself is faulty? If I understand correctly this sensor tells the GEMS ECU what speed the engine is turning. If there's no signal - no fuel nor spark.

I have had similar problems with hotwire (and flapper)-type injection systems, in which the same information comes from the negative terminal of coil.

EDIT: I checked the workshop manual. It should go to limp-mode when this sensor fails - so it is not the probable cause. I'm not familiar with the gems system though. However, engine coolant temp sensor could explain hot starting issues. If it fails the ECU thinks that the engine is cold and makes the car run extremely rich or fail to start completely when hot (at least on RRC:s). It could be the connector also.

Click to expand...

if that were the case it would smell stongly of petrol and run like a pig once started

 

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Don

New Member

• Apr 3, 2007

• #7

Had a similar problem with my P38 4.0ltr which turned out to be the fuel relay under the bonnet in the main fuse/relay box which I changed and have never had the problem since.

You can switch one of the fan relays to try it and see.

Hope it helps.

Don

 

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TimoV

New Member

• Apr 4, 2007

• #8

rick071155 said:

if that were the case it would smell stongly of petrol and run like a pig once started

Click to expand...

Yup, that would be the case. In both the crank-signal and ECT-signal cases it should go to limp mode.

Apparently the gems system is a bit more sophisticated compared to Lucas 14CUX and the ancient 4CU.

It could be the fuel pump relay (as Don suggested) - or even the inertia switch. Both of them quite effectively stop the fuel running if faulty. Loose or corroded connector might be the ultimate cause. Heat expansion of connectors (or the relays) points to the engine bay area.

You shoud also check the points where this system is earthed.

 

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eightinavee

Well-Known Member

• Apr 4, 2007

• #9

If the crank sensor fails it will not start,simple as that.If the round alloy plate it is in comes loose it can cause all sorts of starting/running issues.Worth checking it out,also drop the lower alloy flywheel cover plate and check the 36 tangs that the CPS reads - any damage and again,all sorts of problems.
Coolant temp,AFM,fuel temp,cam sensor and TPS can all be disconnected and the engine should still start,(but run poorly and log loads of faults) the crank sensor has to work for it to run.
Good luck.

 

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TimoV

New Member

• Apr 4, 2007

• #10

eightinavee said:

If the crank sensor fails it will not start,simple as that..

Click to expand...

I stand corrected - thanks. I read the workshop manual for this system again - with glasses on. It clearly states that the engine won't start without this signal . So it is similar to the earlier systems in this sense. No engine speed signal - no go.

 

Bradj999

New Member

• Apr 4, 2007

• #11

Eightinavee if I were half as knowledgeable as you I could make thousands of pounds a week fixing Land Rovers. Ho hum. I could be your apprentice just like in the "karate kid" films. "Bradley san"

 

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P38 Owner

New Member

• Apr 5, 2007

• #12

Hi all,

It looks like its a fuel delivery problem.

so this is what I have found...........when the ignition is terned on the fuel pump is not running. so like suggested I switch the relay for the pump with the fan one and it has made no diffrence.

When interegated with autologic. I told the system to run the pump only. when activated the relay switches but thats about it. still no pump.

Am I right in saying that there is nothing in between the fuel pump relay and the pump? electrically

or is the inertia switch linked in between?

I am going to do some more tests tomorrow. but if it terns out to be a fuel pump fault. i am going to be rather ticked of as I only fitted this one last sat? and being that its pump no 3.

B.