Just for info. The lift pump will only work on pre 1999 P38 when glows are lit or when engine is running. Post 1999 it will work with glows, when engine is being cranked or with engine running. So it is important to know the year of car before advising someone to crank engine to run lift pump. Pre 1999 it just will not happen. All it will do is flatten the battery. Fuel lift pump can be made to run at all times by taking a live feed from battery + to socket 5 on relay 12. 5 is the one contrary in orientation to the other three. This done with ignition OFF. And is the method of checking fuel flow from lift pump. A minimum of 180 Ml should be pumped into a measuring jug in a ten second time period. The injection pump will suck fuel from tank if lift pump is not working (providing the feed is primed and there is no air in the feed pipe) but will give a lack of power on inclines or hard acceleration. Lift pump and fuel pick up attached to it are within 1/4" of bottom of tank so lift pump cannot suck air if tank has fuel in it. If pipe from pump to outlet on lift pump is cracked air cannot be fed to engine, fuel can only flow out. However if feed pipe is cracked and pump is inoperative air would be drawn by injection pump suction if crack was above fuel level. Even if feed pipe from pump to pump outlet is sound another place air can be drawn in with this scenario is the O'rings on either side of the fuel filter.
 
wammers said:
Just for info. The lift pump will only work on pre 1999 P38 when glows are lit or when engine is running. Post 1999 it will work with glows, when engine is being cranked or with engine running. So it is important to know the year of car before advising someone to crank engine to run lift pump. Pre 1999 it just will not happen. All it will do is flatten the battery. Fuel lift pump can be made to run at all times by taking a live feed from battery + to socket 5 on relay 12. 5 is the one contrary in orientation to the other three. This done with ignition OFF. And is the method of checking fuel flow from lift pump. A minimum of 180 Ml should be pumped into a measuring jug in a ten second time period. The injection pump will suck fuel from tank if lift pump is not working (providing the feed is primed and there is no air in the feed pipe) but will give a lack of power on inclines or hard acceleration. Lift pump and fuel pick up attached to it are within 1/4" of bottom of tank so lift pump cannot suck air if tank has fuel in it. If pipe from pump to outlet on lift pump is cracked air cannot be fed to engine, fuel can only flow out. However if feed pipe is cracked and pump is inoperative air would be drawn by injection pump suction if crack was above fuel level. Even if feed pipe from pump to pump outlet is sound another place air can be drawn in with this scenario is the O'rings on either side of the fuel filter.
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Wammers the fuel pump working part makes no sence as if the engine was warm then you would not have the use of glows so would have to rely on the cps as to know to turn intank pump on?its like you saying the intank pump only works on a cold engine it always works when the engine is being cranked or should I say reciving a signal from the cps :):):)and a not working pump jumping relay isn't going to tell you if its the pump or the cable that leads to it best to start at the end and work back if pump doesn't fire up .
 
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Grit Valve said:
Wammers the fuel pump working part makes no sence as if the engine was warm then you would not have the use of glows so would have to rely on the cps as to know to turn intank pump on?its like you saying the intank pump only works on a cold engine it always works when the engine is being cranked or should I say reciving a signal from the cps :):):)
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Think you need to read it again.:):)
 
wammers said:
Think you need to read it again.:):)
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No need the duration of the glows are no more thsn 5 seconds so there after you only have the cps and if by cranking your car with no fuel comming out if you flattery the battery before realising best let a garage do it :)
 
wammer post filled some gaps.
I've not so much as noticed it down on power but I have noticed it down shifts when on cruise on hills where it didn't used to
with the fuel leak leting air in that the fip cant suck out would make sence if the lift pump is inopp.
also when I bridged the relay earlier with the feed pipe off nothing came out which also points at a faulty lift pump
am I right the intank pump is a right bitch to change?
 
oh and its a 98 s reg
also thinking of fitting a none return valve is this advisable or not and what's the id of the feed pipe
 
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Grit Valve said:
No need the duration of the glows are no more thsn 5 seconds so there after you only have the cps and if by cranking your car with no fuel comming out if you flattery the battery before realising best let a garage do it :)
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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.
 
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.
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Do you mean number four :p
 
gfromleeds said:
oh and its a 98 s reg
also thinking of fitting a none return valve is this advisable or not and what's the id of the feed pipe
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If system is good no need for NRV. Don't mask a problem fix it. None working lift pump is your problem, when you change that all else should go away.
 
Grit Valve said:
So I'm on a motorway my alternator packs up and my intank pump stops don't think so somehow
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Please yourself. The lift pump pull down circuit is powered directly from the alternator when the engine is running. If the engine is running and the alternator is not giving power the lift pump will not run simple as that. Have a read when you find out you are wrong no need to apologise. Just take it that you learned something.
 
hey hey it dint want to start a fight lol
dint want to start cutting my floor up either, but think its gona be easier than dropping a tank that's been on for 15year and is about 60 liters full
 
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wammers said:
No fight just trying to correct some misapprehensions. Grit has them now and again. :):)
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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 .
 
lol gona see about pulling the lift pump tomoz
what's the gap between the floor and the top of the tank? last thing I need is to cut into the tank or any of the pipes/wires
also is it just 2 wires to test it when its in my hand ive got to have it running for Monday so am gona have to get a breaker part unless anyone knows where I can get a new one on a Sunday?
 
gfromleeds said:
lol gona see about pulling the lift pump tomoz
what's the gap between the floor and the top of the tank? last thing I need is to cut into the tank or any of the pipes/wires
also is it just 2 wires to test it when its in my hand ive got to have it running for Monday so am gona have to get a breaker part unless anyone knows where I can get a new one on a Sunday?
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You can drain it using gravity so is it seems,it was said that it can't pull air if intank is not working so this means you can suck on fuel feed pipe lower it with a added tube and as long as its lower than the fuel tank gravity will do its work yea right good luck
 
gfromleeds said:
lol gona see about pulling the lift pump tomoz
what's the gap between the floor and the top of the tank? last thing I need is to cut into the tank or any of the pipes/wires
also is it just 2 wires to test it when its in my hand ive got to have it running for Monday so am gona have to get a breaker part unless anyone knows where I can get a new one on a Sunday?
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Have you seen CANYON's run through of how and where to cut? If you need it just put 'canyon' into the search function.
 
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