RV8 Efi fuel PRE FILTER query
Discussion
Hi guys,
replacing the fuel pump on my 3.5 efi truck.
It has an external pump with an alloy racing fuel tank setup. Its the cylindrical bosch type, but it was shot so I ordered a replacement, but it recomends fitting a pre filter between the tank and pump (which had not been done previously)
What sort of filter do i need to use? can I just use a standard fuel filter like this one
http://www.google.co.uk/imgres?q=petrol+filter&...
as its going in before the high pressure part of the system
thanks
replacing the fuel pump on my 3.5 efi truck.
It has an external pump with an alloy racing fuel tank setup. Its the cylindrical bosch type, but it was shot so I ordered a replacement, but it recomends fitting a pre filter between the tank and pump (which had not been done previously)
What sort of filter do i need to use? can I just use a standard fuel filter like this one
http://www.google.co.uk/imgres?q=petrol+filter&...
as its going in before the high pressure part of the system
thanks
Steve_D said:
It would be a pressed steel canister i'm guessing 100mm diameter and about as long.
Steve
cheers for the help chaps,Steve
I see steveD, in that case the truck has got one I think, however it is after the fuel pump at the moment, so I will do some jiggling around and get it in before the pump, all this efi stuff is newto me, just ran carbs on v8's before lol, but tbh i'm glad to see the back of them and move more into the 21st century-ish
Think that installing the existing fuel filter as pre wouldn't work. Standard it has this filter after the efi-pump and is thus a high pressure type and wouldn't recommend it as being used as pre-filter. Not intended to be used like that, it probably won't flow enough by gravity alone and perhaps you get away with it if the efi-pump has some sucking capacity....
Rob
Rob
350zwelgje said:
Think that installing the existing fuel filter as pre wouldn't work. Standard it has this filter after the efi-pump and is thus a high pressure type and wouldn't recommend it as being used as pre-filter. Not intended to be used like that, it probably won't flow enough by gravity alone and perhaps you get away with it if the efi-pump has some sucking capacity....
Rob
ah ok i see, thats probably why it is like it is then.Rob
I guess i could just leave it as it is, as its obv been used like that for quite a while, and tbh the tank looks pretty clean in there as its an alloy race tank, not a rusty old tank full of cr*p at the bottom, and i dont plan on pouring any dirt into it lol.
Think ill get the truck all up n running first, then if its all good invest in a sytec pre filter probably.
I dont even know if the truck moves yet
You need to understand the subtle differences in requirements for "pre" and "post" pressure pump filters:
A "pre" pressure pump filter is designed to prevent ralatively large foreign objects entering the pressure stage in the pump and jamming it up or causing excessive wear. Most "roller cell" pumps can actually cope with fairly large particles without failure. To this end, most "pre" filters are just a mesh "sock" type, with filtration of particles above approx 0.5mm. Generally the "pre" filter system is just there to prevent any debris that finds it's way into the fuel tank (not much for a road cat filled from pumps, cvan be quite a lot for a "track" car etc filled from jerry cans / funnels etc!) from causing issues
The "post" pump filter plays a much more important part, as it prevents the ultra fine orrifices in your fuel injectors from being blocked or damaged by much smaller debris. Usually the post pump filter is of the paper element type, with filtration down to significantly less than 0.1mm. Some of this debris actually comes from the pressure pump (mostly metalic and carbon particles from the pump motor brushes etc). If you have insufficent post pump filtering, usually the small "basket" filters in the inlet pipe of each injector become blocked, usually resulting in a dead engine soon after as one cylinder leans out........)
Both filter systems must be capable of flowing a sufficent amount of fuel to support your power requirement, ideally with the pre filter having much less restriction to avoid unecessarily increasing the pressure ratio of the pressure pump (which really hurts performance)
You can buy the sock type in tank filters from various places, and i would recommened using one of these on your fuel pick up pipe in your tank, in conjunction with a decently sized free flowing paper element filter post pressure pump. Pretty much all of the "pretty" aftermarket racing filters are a massive waste of money. Generally having worse filtration and a high pressure loss than a boggo std OEM type filter you can buy for a tenth of the price............
A "pre" pressure pump filter is designed to prevent ralatively large foreign objects entering the pressure stage in the pump and jamming it up or causing excessive wear. Most "roller cell" pumps can actually cope with fairly large particles without failure. To this end, most "pre" filters are just a mesh "sock" type, with filtration of particles above approx 0.5mm. Generally the "pre" filter system is just there to prevent any debris that finds it's way into the fuel tank (not much for a road cat filled from pumps, cvan be quite a lot for a "track" car etc filled from jerry cans / funnels etc!) from causing issues
The "post" pump filter plays a much more important part, as it prevents the ultra fine orrifices in your fuel injectors from being blocked or damaged by much smaller debris. Usually the post pump filter is of the paper element type, with filtration down to significantly less than 0.1mm. Some of this debris actually comes from the pressure pump (mostly metalic and carbon particles from the pump motor brushes etc). If you have insufficent post pump filtering, usually the small "basket" filters in the inlet pipe of each injector become blocked, usually resulting in a dead engine soon after as one cylinder leans out........)
Both filter systems must be capable of flowing a sufficent amount of fuel to support your power requirement, ideally with the pre filter having much less restriction to avoid unecessarily increasing the pressure ratio of the pressure pump (which really hurts performance)
You can buy the sock type in tank filters from various places, and i would recommened using one of these on your fuel pick up pipe in your tank, in conjunction with a decently sized free flowing paper element filter post pressure pump. Pretty much all of the "pretty" aftermarket racing filters are a massive waste of money. Generally having worse filtration and a high pressure loss than a boggo std OEM type filter you can buy for a tenth of the price............
Max_Torque said:
You need to understand the subtle differences in requirements for "pre" and "post" pressure pump filters:
A "pre" pressure pump filter is designed to prevent ralatively large foreign objects entering the pressure stage in the pump and jamming it up or causing excessive wear. Most "roller cell" pumps can actually cope with fairly large particles without failure. To this end, most "pre" filters are just a mesh "sock" type, with filtration of particles above approx 0.5mm. Generally the "pre" filter system is just there to prevent any debris that finds it's way into the fuel tank (not much for a road cat filled from pumps, cvan be quite a lot for a "track" car etc filled from jerry cans / funnels etc!) from causing issues
The "post" pump filter plays a much more important part, as it prevents the ultra fine orrifices in your fuel injectors from being blocked or damaged by much smaller debris. Usually the post pump filter is of the paper element type, with filtration down to significantly less than 0.1mm. Some of this debris actually comes from the pressure pump (mostly metalic and carbon particles from the pump motor brushes etc). If you have insufficent post pump filtering, usually the small "basket" filters in the inlet pipe of each injector become blocked, usually resulting in a dead engine soon after as one cylinder leans out........)
Both filter systems must be capable of flowing a sufficent amount of fuel to support your power requirement, ideally with the pre filter having much less restriction to avoid unecessarily increasing the pressure ratio of the pressure pump (which really hurts performance)
You can buy the sock type in tank filters from various places, and i would recommened using one of these on your fuel pick up pipe in your tank, in conjunction with a decently sized free flowing paper element filter post pressure pump. Pretty much all of the "pretty" aftermarket racing filters are a massive waste of money. Generally having worse filtration and a high pressure loss than a boggo std OEM type filter you can buy for a tenth of the price............
Thanks for sharing your knowlegde there maxtorque, that has really helped clear it up!A "pre" pressure pump filter is designed to prevent ralatively large foreign objects entering the pressure stage in the pump and jamming it up or causing excessive wear. Most "roller cell" pumps can actually cope with fairly large particles without failure. To this end, most "pre" filters are just a mesh "sock" type, with filtration of particles above approx 0.5mm. Generally the "pre" filter system is just there to prevent any debris that finds it's way into the fuel tank (not much for a road cat filled from pumps, cvan be quite a lot for a "track" car etc filled from jerry cans / funnels etc!) from causing issues
The "post" pump filter plays a much more important part, as it prevents the ultra fine orrifices in your fuel injectors from being blocked or damaged by much smaller debris. Usually the post pump filter is of the paper element type, with filtration down to significantly less than 0.1mm. Some of this debris actually comes from the pressure pump (mostly metalic and carbon particles from the pump motor brushes etc). If you have insufficent post pump filtering, usually the small "basket" filters in the inlet pipe of each injector become blocked, usually resulting in a dead engine soon after as one cylinder leans out........)
Both filter systems must be capable of flowing a sufficent amount of fuel to support your power requirement, ideally with the pre filter having much less restriction to avoid unecessarily increasing the pressure ratio of the pressure pump (which really hurts performance)
You can buy the sock type in tank filters from various places, and i would recommened using one of these on your fuel pick up pipe in your tank, in conjunction with a decently sized free flowing paper element filter post pressure pump. Pretty much all of the "pretty" aftermarket racing filters are a massive waste of money. Generally having worse filtration and a high pressure loss than a boggo std OEM type filter you can buy for a tenth of the price............
I'll defo try and get one of the sock type filters in there then. ill examine the tank later as its a custom built alloy racing jobby, so would be supprided if it didnt have a filter in it already somewhere.
This is the problem with buying a custom vehicle from an auction, in that you have no one to speak to about whats been done, or not, thanks eddy
btw the positive to the fuel pump was dead.
I know this is controlled by the ecu in a flapper, but i think i've got a hotwire, as cant see a flap in there.
So am i ok to run a live thats constant when the ignition is on, and during cranking to the fuel pump insted? Or does power to the pump have to be regulated somehow? thanks
I know this is controlled by the ecu in a flapper, but i think i've got a hotwire, as cant see a flap in there.
So am i ok to run a live thats constant when the ignition is on, and during cranking to the fuel pump insted? Or does power to the pump have to be regulated somehow? thanks
The supply to the pump should come from the fuel pump relay. This relay is controlled by the ECU. When you turn on the ignition it will run the pump for a few seconds just to prime the system. It will not come on again until the ECU detects cranking revs.
Do not bypass this relay as it is for your safety. If you crash and the engine stops the ecu will shut down the pump so fuel is not continually pumped into the wreckage.
Steve
Do not bypass this relay as it is for your safety. If you crash and the engine stops the ecu will shut down the pump so fuel is not continually pumped into the wreckage.
Steve
Steve_D said:
The supply to the pump should come from the fuel pump relay. This relay is controlled by the ECU. When you turn on the ignition it will run the pump for a few seconds just to prime the system. It will not come on again until the ECU detects cranking revs.
Do not bypass this relay as it is for your safety. If you crash and the engine stops the ecu will shut down the pump so fuel is not continually pumped into the wreckage.
Steve
ok makes sense, i don't suppose you would know where thats located on a range rover??Do not bypass this relay as it is for your safety. If you crash and the engine stops the ecu will shut down the pump so fuel is not continually pumped into the wreckage.
Steve
also just tried to start it with my bodged positive wire that i need to sort out.
New fuel pump is pumping away fine, fuel is coming through the post pump filter at high pressure, but after that it doesnt appear to be getting to the engine bay ?
the engine will fire on easy start, the nothing.
plugs are bone dry!!!
Where can i check next along the line to see if fuel is coming in, will i be able to see anything if i pop the top of the plenum??? cheers
New fuel pump is pumping away fine, fuel is coming through the post pump filter at high pressure, but after that it doesnt appear to be getting to the engine bay ?
the engine will fire on easy start, the nothing.
plugs are bone dry!!!
Where can i check next along the line to see if fuel is coming in, will i be able to see anything if i pop the top of the plenum??? cheers
stevieturbo said:
More info required in the events leading up to the non start.
Seems you are trying to fix symptoms of a problem, rather than a cause.
If the fuel pump isnt being powered up, then good chance there is an ecu related problem. Also backed up by the fact the injectors may not be firing.
fair point, but if thats the case then would it still run on easystart? It'll idle and rev if you spray it in constantly?Seems you are trying to fix symptoms of a problem, rather than a cause.
If the fuel pump isnt being powered up, then good chance there is an ecu related problem. Also backed up by the fact the injectors may not be firing.
Any idea where the fuel pump relay maybe located on an f reg range rover? i've had a look under the seat as suggested but its not there?? It has been made into a bobtail pickup so probably been moved. However as the previuos owner is unfortunately no longer with us its abit hard to ask him where it is!
retroracing said:
fair point, but if thats the case then would it still run on easystart? It'll idle and rev if you spray it in constantly?
Any idea where the fuel pump relay maybe located on an f reg range rover? i've had a look under the seat as suggested but its not there?? It has been made into a bobtail pickup so probably been moved. However as the previuos owner is unfortunately no longer with us its abit hard to ask him where it is!
You are diving in without doing any basic diagnostics.Any idea where the fuel pump relay maybe located on an f reg range rover? i've had a look under the seat as suggested but its not there?? It has been made into a bobtail pickup so probably been moved. However as the previuos owner is unfortunately no longer with us its abit hard to ask him where it is!
Do you have power to the pump on cranking ? Does the pump prime ? Does it receive the power to operate ?
Do you get spark ? Do you get a signal at the injector ?
I'd put money on the injectors not actually firing at the moment.
(if the pressure pump is running, and fuel is being pumped to the fuel rail (easy to check, just carefully crack off one of the fittings and see if some fuel dribbles out (note the carefully bit!!, use a rag around the fitting to catch any spray etc, and only crack the fitting a small amount) then if no fuel is getting into the engine, the injectors are either all blocked or not firing. With the ignition on, check you have a nice 12v power feed to the injectors, and when cranking, use a led or small bulb to see if the ecu is actually grounding the injectors as the engine cranks!)
(if the pressure pump is running, and fuel is being pumped to the fuel rail (easy to check, just carefully crack off one of the fittings and see if some fuel dribbles out (note the carefully bit!!, use a rag around the fitting to catch any spray etc, and only crack the fitting a small amount) then if no fuel is getting into the engine, the injectors are either all blocked or not firing. With the ignition on, check you have a nice 12v power feed to the injectors, and when cranking, use a led or small bulb to see if the ecu is actually grounding the injectors as the engine cranks!)
retroracing said:
Steve_D said:
The supply to the pump should come from the fuel pump relay. This relay is controlled by the ECU. When you turn on the ignition it will run the pump for a few seconds just to prime the system. It will not come on again until the ECU detects cranking revs.
Do not bypass this relay as it is for your safety. If you crash and the engine stops the ecu will shut down the pump so fuel is not continually pumped into the wreckage.
Steve
ok makes sense, i don't suppose you would know where thats located on a range rover??Do not bypass this relay as it is for your safety. If you crash and the engine stops the ecu will shut down the pump so fuel is not continually pumped into the wreckage.
Steve
Steve
ok thanks for the advise guys. Yes there is a very strong spark, but think i need to track down this fuel pump relay, and check the injectors as suggested.
The wiring is like a birds nest in this car, and i cant see anything under the drivers seat so will have to have a look about, and start tracing wires.
The wonders of modified cars lol!
The wiring is like a birds nest in this car, and i cant see anything under the drivers seat so will have to have a look about, and start tracing wires.
The wonders of modified cars lol!
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