Club 80-90 Forums

Be aware that some electric pumps do not provide enough fuel at motorway speeds, especially on hills.

Really ?

I looked at this : https://www.merlinmotorsport.co.uk/p/fa ... -fac-60106

26 gallons / hour is 2 litres a minute which should be more than adequate

Or look at it another way.... say 80 mph at 4 mpg is 20 gallons per hour

Whats wrong with a T25 injection fuel pump?

itchyfeet wrote:Whats wrong with a T25 injection fuel pump?

Nothing, if you have fuel injection.

As far as Facet Posiflow pumps go I've never had a problem with a 2l with twin carbs and they can drink fuel at 70+ mph

bigherb wrote:

itchyfeet wrote:Whats wrong with a T25 injection fuel pump?

Nothing, if you have fuel injection.

As far as Facet Posiflow pumps go I've never had a problem with a 2l with twin carbs and they can drink fuel at 70+ mph

let me rephrase, whats wrong with a T25 injection pump for a DG or DF or one of those early prototypes?

itchyfeet wrote:

bigherb wrote:

itchyfeet wrote:Whats wrong with a T25 injection fuel pump?

Nothing, if you have fuel injection.

As far as Facet Posiflow pumps go I've never had a problem with a 2l with twin carbs and they can drink fuel at 70+ mph

let me rephrase, whats wrong with a T25 injection pump for a DG or DF or one of those early prototypes?

It is a constant flow pump at much higher pressure.

itchyfeet wrote:Whats wrong with a T25 injection fuel pump?

It's all about pressure and flow.

A carb engine needs the flow of fuel to allow the engine to develop the power it needs. The pipework is not designed for high pressure, so is more prone to leaks with high pressure.

FI systems require the same flow at a certain pressure to deliver the required fuel correctly. Typically an injection pump will operate at 5 bar with the regulator set at 3. The pump I linked to, based on earlier comments, runs at 0.3 bar.

937carrera wrote:Really ?

I looked at this : https://www.merlinmotorsport.co.uk/p/fa ... -fac-60106

26 gallons / hour is 2 litres a minute which should be more than adequate

Or look at it another way.... say 80 mph at 4 mpg is 20 gallons per hour

I can see that the figures work, but can only speak from experience with the pump as installed when I changed to LPG. The pump was bought new( not a Chinese copy) and fitted with the relay and petrol supply solenoid in the engine compartment, when switched to petrol more than 3/4 throttle would create fuel starvation on the motorway, having thought that the pump was fitted too far from the tank, I then moved it to the chassis rail by the tank outlet, it made no difference. I then changed to the cube type pump and issue has been resolved. I can only conclude that the posiflow was not able to supply enough fuel, was faulty, or that the cut off solenoid creates a significant restriction. The same symptoms occurred with both a Weber carb and the Pierburg when put back on.

P.S. having rebuilt the Pierburg and put it back on the camper I have noticed that the overall performance is the same but watching the air/ fuel gauge shows that the Weber has a cruder on/off lean/rich delivery where the Pierburg is more subtle . Strangely consumption appears to be the same.

937carrera wrote:

itchyfeet wrote:Whats wrong with a T25 injection fuel pump?

It's all about pressure and flow.

A carb engine needs the flow of fuel to allow the engine to develop the power it needs. The pipework is not designed for high pressure, so is more prone to leaks with high pressure.

FI systems require the same flow at a certain pressure to deliver the required fuel correctly. Typically an injection pump will operate at 5 bar with the regulator set at 3. The pump I linked to, based on earlier comments, runs at 0.3 bar.

which just goes to show there is a lot more to it then just bodging in a pump.

bigherb wrote: It is a constant flow pump at much higher pressure.

the cheap ( and some may say nasty ) square farct pump for about £15 off the bay of fleas can happily deliver enough for my 2.1 of a carb at any speed ....

no need for any regulator and sits happily on the inner sill by the tank ..... ok, you can hear it at idle, but that is a good thing in my book, i know its working and can hear when the carb has fuel when strting from dry
https://www.ebay.co.uk/itm/UNIVERSAL-SO ... SwKtVWzCvd" onclick="window.open(this.href);return false;

weimarbus wrote: I then changed to the cube type pump and issue has been resolved.

Do you have a link to this please?

weimarbus wrote:

937carrera wrote:Really ?

I looked at this : https://www.merlinmotorsport.co.uk/p/fa ... -fac-60106

26 gallons / hour is 2 litres a minute which should be more than adequate

Or look at it another way.... say 80 mph at 4 mpg is 20 gallons per hour

I can see that the figures work, but can only speak from experience with the pump as installed when I changed to LPG. The pump was bought new( not a Chinese copy) and fitted with the relay and petrol supply solenoid in the engine compartment, when switched to petrol more than 3/4 throttle would create fuel starvation on the motorway, having thought that the pump was fitted too far from the tank, I then moved it to the chassis rail by the tank outlet, it made no difference. I then changed to the cube type pump and issue has been resolved. I can only conclude that the posiflow was not able to supply enough fuel, was faulty, or that the cut off solenoid creates a significant restriction. The same symptoms occurred with both a Weber carb and the Pierburg when put back on.

P.S. having rebuilt the Pierburg and put it back on the camper I have noticed that the overall performance is the same but watching the air/ fuel gauge shows that the Weber has a cruder on/off lean/rich delivery where the Pierburg is more subtle . Strangely consumption appears to be the same.

You must have been unlucky! I have had posiflow on 1.9 WBX with webber, pierberg and twin 40 HPMX carbs and it fed all of them fine (plus some very thirsty air cooled stuff). They are push pumps rather than pull, so need to sit next to tank outlet. Only issue is that they are very sensitive to small particles so good filter is important.

And back to what started the thread, need to be wired in so they cut off if you crash. Seen some wired direct to the coil which is terrifying as coil and hence pump can remain live when you are upside in a ditch, just pumping petrol out at 26 gallons an hour....

itchyfeet wrote:

weimarbus wrote: I then changed to the cube type pump and issue has been resolved.

Do you have a link to this please?[/quote

Sorry Itchy, I'm a dinosaur with computers, so don't know how to do link. I bought the genuine 'fast road engine' cube from 'Demon tweeks'. but with a recco from Mocki for the fleabay one it has to be worth a try at £15 . I had a cheaper copy on the buggy feeding the twin Dellortos and it was fine.

Hi, I'm planning on fitting a facet poziflow pump but unclear about the regulator. Assume I need one though as up to 6 PSI at the carb seems high and risking leaks. Any experiences of this setup welcome. Thanks Mark