Fuel Pump Pressure

W

winston

New Member
Hi there
Can anyone tell me what the correct pressure for the fuel pump on series 2 p6 v8,should be/
As my car surges when the accelerator is applied.All the lines,carb's etc have been checked and are fine.
Currently i am told the fuel pump in my car pumps at .25 bar,and this should be .5 bar.Is this correct?
Regards
winston
 
Around 1.5 psi should be fine, I think that's about 0.1 bar above atmospheric, or 1.1bar absolute, depending on how you are describing your pressures.

So yours sounds fine to me.

Can you describe what you mean by "surges" please. ie what gear are you in, what speed, what does the car do? And is it Auto or Manual?

Chris
 
I think the manual fuel pump is rated at 3.5 to 4 psi which is .25 bar if one bar is 14.7 psi . .5 bar seems too high
 
The mechanical fuel pump delivers petrol within the range of 3.5 to 5.0 psi. These figures I take directly from the Official workshop manual.

Winston,...does your Rover run a mechanical or electric fuel pump?

Ron.
 
chrisyork said:
Around 1.5 psi should be fine, I think that's about 0.1 bar above atmospheric, or 1.1bar absolute, depending on how you are describing your pressures.

So yours sounds fine to me.

Can you describe what you mean by "surges" please. ie what gear are you in, what speed, what does the car do? And is it Auto or Manual?

Chris
Click to expand...

Chris thanks for the info.
when you drive a round 100km/h she suddenly loses power as if she has fuel starvation.This results in having to stop until the bowel is full, and then pulling off again.If you keep it below this speed then she seems ok.I have a suspicion that the tank may be causing some sort f blockage,when she is on the move.This will not becomeapparent if she stands stil

Are the tanks made of metal ( i think) and my guess is that there may be some sort ofrust / dirt deposits as a result of age,whch gets sucked to the fuel pump inlet when power is applied.
What are our thoughts?
 
Well that sounds like the classic symptoms of fuel vapourisation. I wasn't clear whether your pump was electric or mechanical? Vapourisation is almost unheard of against an electric pump but common against a mechanical pump. It will also be apparent if you stand for a long period in traffic.

On the basis you have a mechanical pump, then the easiest fix for vapourisation is to re-route the fuel line between the reserve tap on the right side front bulkhead and the fuel pump. At the left side of the engine bay take the line straight on and out into the under wing area by passing it behind and under the steering idler. Then run it down the inner wing to the front of the car and bring it back into the engine bay behind the headlamps. It's then only a very short hop across to the pump.

If you have an electric pump then the problem is most likely to be electrical. The prime suspects are the pump itself (Pacets especially are known to fail gradually with these symptoms), the coil and the ignition condensor in the distributor. All are likely to produce these symptoms whilst in the process of failing.

The tank is unlikely to be the problem, but make sure and check for debris appearing in the fuel filter. Once you've run out of other options there is one known failure mode with the tank. That is the collapse of the plastic mesh sleeve which protects the outlet pipe within the tank. You can get at this by removing the tank sender unit.

Hope that helps and keep us posted how you get on!

Chris
 
Winston wrote,...
when you drive a round 100km/h she suddenly loses power as if she has fuel starvation.This results in having to stop until the bowel is full, and then pulling off again.If you keep it below this speed then she seems ok.I have a suspicion that the tank may be causing some sort f blockage,when she is on the move.This will not becomeapparent if she stands stil
Click to expand...

Hello Winston,

Sounds like starvation rather than vapourisation, so a possible cause is....assuming your engine is running with the mechanical pump..is an inability to maintain the correct volume of fuel as the speed rises, hence the engine will run lean as the level of fuel within each carburettor bowl falls. This will be felt as "surging" which is as you described it.

So remove and overall your mechanical pump with all new parts.

An electric pump on the other hand delivers fuel at a constant rate with delivery independent of engine speed, so if your engine is being fuelled by one of these, then you will need to replace it.

There is also an option that the fuel filter is largely blocked, and this is restricting the delivery of fuel in which case this too should be replaced.

Ron.
 
Hi - I think this question would be appropriate for this thread.

Will this fuel pump (see link) work in my 1972 Rover P6 V8. Rimmer's don't know. They are telling me to find out the fuel pressure required for the car. Can't see an exact answer to this in this thread as it talks about the pressure the fuel pump works at but I need to know the quantity of fuel required by the carbs that is required to be pumped.

As you can see from the link that this fuel pump delivers 17.5 gallons per hour and has a 2.5 - 3 psi delivery pressure.

Fuel Pump - SU - Points Type - Original | Rimmer Bros

Pictures of the fuel pump currently in my P6

20180411_173141_zps1tu78htz.jpg


20180411_173130_zpsun4ffiod.jpg
 
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Hi, yes it will be OK. That a high capacity pump all those in the list have twin SU's and at least one has a triple carb set up.

Colin
 
Another possibility is that at one point the float bowl needle & seats were replaced using ones with tiny holes. While all the SU needle & seats look the same, they come in at least two bore sizes. The symptoms are exactly as you describe.

Yours
Vern
 
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