diesel wont start

This site contains affiliate links for which LandyZone may be compensated if you make a purchase.
Grit Valve said:
Like the glow plug bank of feed wire are one 6 x 5 amps draw totalling 30 amps now your telling me number 6 is linked to the alternator what never head of it in my life .
Click to expand...

No i am not saying that. Take a look at the wiring diagrams for the fuel lift pump relay 12. You will see two circuits with diodes one from number six glow plug. One from alternator on pre 1999 cars. On 1999 on cars there are three circuits with diodes, one from number six glow plug, one from alternator and one from starter relay. The diodes are to prevent reverse power flow. So on pre 99 cars there are two methods of pulling the relay, a feed from glow plug and a feed alternator. Protected by two diodes so they cannot interact. On 99 on cars three ways of powering relay pull down, feed from number six glow plug, feed from starter relay and feed from alternator. All protected by diodes to prevent interaction.
 
wammers said:
No i am not saying that. Take a look at the wiring diagrams for the fuel lift pump relay 12. You will see two circuits with diodes one from number six glow plug. One from alternator on pre 1999 cars. On 1999 on cars there are three circuits with diodes, one from number six glow plug, one from alternator and one from starter relay. The diodes are to prevent reverse power flow. So on pre 99 cars there are two methods of pulling the relay, a feed from glow plug and a feed alternator. Protected by two diodes so they cannot interact. On 99 on cars three ways of powering relay pull down, feed from number six glow plug, feed from starter relay and feed from alternator. All protected by diodes to prevent interaction.
Click to expand...

At then end of the day forget the glow plug circuit especially if hot the pump don't fire up until the key is turned too position two in that case the car is turning over or running make no difference you still need to crank it !
 
Last edited:
Grit Valve said:
At then end of the day forget the glow plug circuit especially if hot the pump don't fire up until the key it turned too position two in that case the car is turning over or running make no difference you still need to crank it !
Click to expand...

Don't think you quite understand do you? ON A PRE 1999 P38 DIESEL THE LIFT PUMP WILL NOT RUN WHEN THE ENGINE IS BEING CRANKED.
 
wammers said:
Don't think you quite understand do you? ON A PRE 1999 P38 DIESEL THE LIFT PUMP WILL NOT RUN WHEN THE ENGINE IS BEING CRANKED.
Click to expand...
so the scenario is been out in the car its a bloody hot day car was right up to its temputre on return to car an hour and a half later the glow plugs arnt needed As the car is still registering warm but I have developed some air in my clear pipe and are about to Start my car at what point does the intank pump reprime the system in laymens terms pre 99
 
Last edited:
Grit Valve said:
so the scenario is been out in the car its a bloody hot day car was right up to its temputre on return to car an hour and a half later the glow plugs arnt needed As the car is still registering warm but I have developed some air in my clear pipe and are about to Start my car at what point does the intank pump reprime the system in laymens terms pre 99
Click to expand...

When the engine is running. That was one of the problems they tried to sort by making the lift pump run on cranking on 1999 on cars.
 
wammers said:
When the engine is running. That was one of the problems they tried to sort by making the lift pump run on cranking on 1999 on cars.
Click to expand...
Aw I think I'm halfway there, so what is the differance to a engine cranking over reciving signals from the cps number 4 injector and a slight output from an alternator compaired to a running engine ????
 
Last edited:
Grit Valve said:
Aw I think I'm halfway there, so what is the differance to a engine cranking over reciving signals from the cps number 4 injector and a slight output from an alternator compaired to a running engine ????
Click to expand...

The only thing the ECU takes any notice of on start up is the ECU temp sensor. It then sets pre start fuel and timing according to temp reading. Nothing else kicks in until the engine is doing over 500 RPM or so. That is why it jumps to fast idle then drops back even when it's hot. As i said earlier on your car which i think is year 2000, lift pump is on whilst glow plugs are on, relay pulled by feed from number six glow plug. When the engine is being cranked, relay pulled by starter relay. Or when engine is running relay pulled by alternator. All are connected in common to pin 1 on relay 12. But protected from interaction by three diodes. So that as each is powered they cannot react with the other two.
 
Last edited:
An extract from a previous thread look
For the question marks I have added :)


I would just like to say thank you to:

Wammers.
Arron beast,
Derek ward,
Takdrivers,
Enery8.

For all your help and advice.
Yippeeee....my car is running, though it was not all straight forward.
Tried bridging relay...no luck.
Tried new relay...no luck.
So went all in and cut a hole in the floor changed fuel pump.
It was difficult getting the rubber seal to fit around the pump opening but got there in the end.


???????I left the fuel pipe off at the filter end and placed it into a container then turned the car over a few times to bleed the pipe.???????


once the pipe was bled i conected it back to the filter.
Turned the ignition a few times and voila........engine was running again.


Also a big thank you to canyan for putting the cutting instructions on the site.

Mike.

PS ITS MY BIRTHDAY TODAY......................LOL
Btw this is a pre 9& car :):):)
 
Grit Valve said:
An extract from a previous thread look
For the question marks I have added :)


I would just like to say thank you to:

Wammers.
Arron beast,
Derek ward,
Takdrivers,
Enery8.

For all your help and advice.
Yippeeee....my car is running, though it was not all straight forward.
Tried bridging relay...no luck.
Tried new relay...no luck.
So went all in and cut a hole in the floor changed fuel pump.
It was difficult getting the rubber seal to fit around the pump opening but got there in the end.


???????I left the fuel pipe off at the filter end and placed it into a container then turned the car over a few times to bleed the pipe.???????


once the pipe was bled i conected it back to the filter.
Turned the ignition a few times and voila........engine was running again.


Also a big thank you to canyan for putting the cutting instructions on the site.

Mike.

PS ITS MY BIRTHDAY TODAY......................LOL
Btw this is a pre 9& car :):):)
Click to expand...

Your point is?
 
wammers said:
glows on a cold morning would be seven or eight seconds maybe be more. They are variable duration depending on engine temp. Cps has nothing to do with lift pump. Lift pump is powered on a pre 1999 car by feed from number six glow plug when engine is cold or directly from alternator when engine is running. This done by a voltage reversal. It will not run on cranking. On the 1999 my it is powered by feed from number six glow plug when cold or from starter relay when cranked or direct from alternator as said before. And additional diode and circuit from starter relay was added to the fuse box in 1999 to enable lift pump running whilst being cranked. Cps has no input into operation of lift pump.
Click to expand...
+1:)
 
You must log in or register to reply here.

Similar threads

jimmacD
Back to the P38 house of pain!
2
Replies
21
Views
2K
Grrrrrr
Grrrrrr
Joe varley
The dreaded 2.7 sport lol HELP
Replies
7
Views
564
Joe varley
Joe varley
Maat
Disco 1 300tdi diesel leak
Replies
11
Views
293
Maat
Maat
M
1992 200tdi 90 High Reving Engine on Start Up🤔
Replies
9
Views
478
kevstar
kevstar
L
Freelander td4 2005 Diesel pump locations
Replies
1
Views
530
brianp38dse
brianp38dse
Back
Top