Higher pressure oil pump relief valve spring
23-06-2015, 01:30 PM
#1
Regular Contributor
Thread Starter
Higher pressure oil pump relief valve spring
I'm trying to find out where to get hold of the stronger spring for the CVH oil pump to hold the pressure a bit higher at idle.
Did the search on here and found a few old threads saying you can get them from Burton Power but I've just talked to them and they no longer sell the spring separately.
Bit of a weird one, oil pressure is low on idle after its hot, gauge reads about 5-8 psi. Plenty of pressure at anything above idle.
The cars been sat for about a year probably, the bottom end only has a few K on it after a full rebuild, and it was OK before being laid up.
It's had a total re-loom and I was out doing some base mapping. The pressure is fine when cold, and even when hot it jumps up when I touch the pedal.
It's a Ford pump bought at ridiculous cost when the bottom end was built.
Things I'm doing tomorrow:
Trying a mechanical pressure gauge (current is electronic and could be affected by the new loom)
New filter, new oil
Pondering if to mess about with the pump relief spring.
Thoughts?
Did the search on here and found a few old threads saying you can get them from Burton Power but I've just talked to them and they no longer sell the spring separately.
Bit of a weird one, oil pressure is low on idle after its hot, gauge reads about 5-8 psi. Plenty of pressure at anything above idle.
The cars been sat for about a year probably, the bottom end only has a few K on it after a full rebuild, and it was OK before being laid up.
It's had a total re-loom and I was out doing some base mapping. The pressure is fine when cold, and even when hot it jumps up when I touch the pedal.
It's a Ford pump bought at ridiculous cost when the bottom end was built.
Things I'm doing tomorrow:
Trying a mechanical pressure gauge (current is electronic and could be affected by the new loom)
New filter, new oil
Pondering if to mess about with the pump relief spring.
Thoughts?
23-06-2015, 02:27 PM
#2
Always a pleasure!
Hi Matt, don't forget your cam fell to bits and sent metal all round the engine, if you've got low oil pressure at idle when hot I would be looking at your shells mate.
Increasing the spring pressure could just be covering up a more serious problem.
Trying a mechanical gauge is a good idea, also check pressure at 3000rpm after a good 30 mins drive, should be about 45psi.
Does the oil light come on at idle too?
Increasing the spring pressure could just be covering up a more serious problem.
Trying a mechanical gauge is a good idea, also check pressure at 3000rpm after a good 30 mins drive, should be about 45psi.
Does the oil light come on at idle too?
23-06-2015, 03:30 PM
#3
Regular Contributor
Thread Starter
Was expecting you'd reply Karl 
Ugh I forgot about that bloody cam. You replaced the original shredded standard one with a newman and flushed it, and that was a while ago so I would have thought if something nasty was going to happen it already would. Shells are at the back of my mind but staying positive for now!!
I know there was suspicion the new cam had been eaten but since you saw it with fuelling issues I discovered the wiring to the pump was so rotten it couldnt cope with the demand (put a bike pump on the FPR to test and added >1 BAR) hence the re-loom. And I also added some hefty new cable for the fuel pump. Out mapping I was getting mid 11s on full boost, and it can easily go richer so I'm happy that problem is cured.
What socket do I need for the ARP bolts holding the rods?
Fuck me I hate dropping the sump
especially while currently recovering from back surgery
Ugh I forgot about that bloody cam. You replaced the original shredded standard one with a newman and flushed it, and that was a while ago so I would have thought if something nasty was going to happen it already would. Shells are at the back of my mind but staying positive for now!!
I know there was suspicion the new cam had been eaten but since you saw it with fuelling issues I discovered the wiring to the pump was so rotten it couldnt cope with the demand (put a bike pump on the FPR to test and added >1 BAR) hence the re-loom. And I also added some hefty new cable for the fuel pump. Out mapping I was getting mid 11s on full boost, and it can easily go richer so I'm happy that problem is cured.
What socket do I need for the ARP bolts holding the rods?
Fuck me I hate dropping the sump
especially while currently recovering from back surgery
23-06-2015, 04:12 PM
#4
Always a pleasure!
lol Always here to help if I can mate 
Yeah that's what I did, hopefully it isn't that but thought it worth a mention as it was a while ago and thought you may have forgotten.
Ah that's good news and very common these days, mid 11's on boost is nice and safe!
I think they are E10? Don't have a set to hand to check though so could be wrong.
How is the back these days, I'm guessing not great as you've had an op?
Yeah that's what I did, hopefully it isn't that but thought it worth a mention as it was a while ago and thought you may have forgotten.
Ah that's good news and very common these days, mid 11's on boost is nice and safe!
I think they are E10? Don't have a set to hand to check though so could be wrong.
How is the back these days, I'm guessing not great as you've had an op?
Last edited by Karl @ FPT; 23-06-2015 at 04:13 PM.
23-06-2015, 04:34 PM
#5
Regular Contributor
Thread Starter
Yeah it got worse, then better, then much much worse, then the NHS finally decided I should get fixed, so had surgery a month or so ago and fingers crossed for a permanent fix.
I will update tomorrow when I've got a mechanical gauge. If that reads low then it's sump off time
I will update tomorrow when I've got a mechanical gauge. If that reads low then it's sump off time
24-06-2015, 11:23 PM
#7
Regular Contributor
Thread Starter
Mechanical TIM gauge results:
20 PSI at hot idle
15 PSI at VERY hot idle (+100C)
and the joints for the mechanical gauge were actually seeping oil
Not amazingly high results but good enough to stop worrying about oil pressure and enjoy the car.
Anyone see what's wrong with the old sender...
20 PSI at hot idle
15 PSI at VERY hot idle (+100C)
and the joints for the mechanical gauge were actually seeping oil
Not amazingly high results but good enough to stop worrying about oil pressure and enjoy the car.
Anyone see what's wrong with the old sender...
Trending Topics
03-07-2015, 09:06 AM
#8
sender looks bent will give mashup reading.
also if you have had it tuned or looked at before, how come noone has tested the power at the pump? also the volt drop and resistance in the earth.
THE first things to check.
You had cam and other stuff done but noone checked the obvious. ?
also if you have had it tuned or looked at before, how come noone has tested the power at the pump? also the volt drop and resistance in the earth.
THE first things to check.
You had cam and other stuff done but noone checked the obvious. ?
03-07-2015, 10:34 AM
#9
Always a pleasure!
sender looks bent will give mashup reading.
also if you have had it tuned or looked at before, how come noone has tested the power at the pump? also the volt drop and resistance in the earth.
THE first things to check.
You had cam and other stuff done but noone checked the obvious. ?
also if you have had it tuned or looked at before, how come noone has tested the power at the pump? also the volt drop and resistance in the earth.
THE first things to check.
You had cam and other stuff done but noone checked the obvious. ?
Sigh... Always ready to jump on people rather than being helpful
Matt had me fit a Newman cam kit, do some thread repair work and other small jobs, I discovered the fueling issue whilst it was with me, informed Matt first before going any further (as I do all my customers if there will be more work adding to the cost of the job) and suggested I check the fuel pump wiring and pump etc. he was in no rush and choose to save money by taking the car home and working on it himself as and when his back problems allowed.
Last edited by Karl @ FPT; 03-07-2015 at 12:01 PM.
09-07-2015, 12:13 PM
#11
Just for some clarification, the spring in the oil pump is the pressure relief spring. Changing this spring changes the peak oil pressure not the oil pressure over all. For example a stiffer spring (or shimmed spring) will increase the oil pressure when the engine is cold and at high rpm.
It will not increase the oil pressure at idle.
Also, measuring the volt drop at the pump is fairly pointless, the 'volt drop' will depend on the current being drawn by the pump which clearly changes with load. A better approach is to measure the resistance of the pump wiring. You can then predict the volt drop for a range of currents and hence pump loads.
To do this properly the resistance should be measured from the pump negative terminal to battery terminal, and from pump positive terminal to battery positive terminal obviously with the pump relay active.
Add the two resistances together (they are in series) and from here you can see if you have a problem.
V = IR, if you have a total resistance in the supply path of 0.5ohms and you predict your pump draws 10A a full load you would do the following:
V = 10*0.5 = 5V so the voltage at the pump would be battery voltage (14V) minus the voltage drop across the resistance = 9V.
It is likely that your fuel pump will not have a current draw of 10A, this is probably more like 6A (you can measure this with a multimeter) and the series resistance would ideally be less than 0.2 ohms.
Again - V=IR so V(drop) = 6*0.2 = 1.2V resulting in a pump voltage of 12.8V.
Interestingly a Bosch 044 pump is rated at 12.8V, with a flow of 4.6L/min at 3.0bar drawing 11amps equating to 700 ish bhp potential.
Either way, my point is that the voltage drop is dependent upon the current being drawn and total series resistance, not on some figure spouted on the internet. Measuring a voltage drop at idle on one car is totally not relevant. For that matter a 5V drop means nothing what so ever as long as the pump can still provide enough fuel to maintain the set pressure of 3-3.5 bar.
A better test would be to install a fuel pressure gauge and to make sure the pressure didn't drop at high loads, replacing the pump wiring for no reason is just stupid.
Motor speed is dictated by voltage, motor torque by current. Pump flow is proportional to pump speed and hence voltage. An 044 at half speed and half flow is still enough for 300bhp at 6.4V assuming enough current can be drawn to maintain pressure. So all this internet scare mungering about pump wiring is mostly rubbish on cars with lower power figures. Unless of course you are intending to make 400bhp with one pump, in which case you should be more concerned.
Rob,
It will not increase the oil pressure at idle.
Also, measuring the volt drop at the pump is fairly pointless, the 'volt drop' will depend on the current being drawn by the pump which clearly changes with load. A better approach is to measure the resistance of the pump wiring. You can then predict the volt drop for a range of currents and hence pump loads.
To do this properly the resistance should be measured from the pump negative terminal to battery terminal, and from pump positive terminal to battery positive terminal obviously with the pump relay active.
Add the two resistances together (they are in series) and from here you can see if you have a problem.
V = IR, if you have a total resistance in the supply path of 0.5ohms and you predict your pump draws 10A a full load you would do the following:
V = 10*0.5 = 5V so the voltage at the pump would be battery voltage (14V) minus the voltage drop across the resistance = 9V.
It is likely that your fuel pump will not have a current draw of 10A, this is probably more like 6A (you can measure this with a multimeter) and the series resistance would ideally be less than 0.2 ohms.
Again - V=IR so V(drop) = 6*0.2 = 1.2V resulting in a pump voltage of 12.8V.
Interestingly a Bosch 044 pump is rated at 12.8V, with a flow of 4.6L/min at 3.0bar drawing 11amps equating to 700 ish bhp potential.
Either way, my point is that the voltage drop is dependent upon the current being drawn and total series resistance, not on some figure spouted on the internet. Measuring a voltage drop at idle on one car is totally not relevant. For that matter a 5V drop means nothing what so ever as long as the pump can still provide enough fuel to maintain the set pressure of 3-3.5 bar.
A better test would be to install a fuel pressure gauge and to make sure the pressure didn't drop at high loads, replacing the pump wiring for no reason is just stupid.
Motor speed is dictated by voltage, motor torque by current. Pump flow is proportional to pump speed and hence voltage. An 044 at half speed and half flow is still enough for 300bhp at 6.4V assuming enough current can be drawn to maintain pressure. So all this internet scare mungering about pump wiring is mostly rubbish on cars with lower power figures. Unless of course you are intending to make 400bhp with one pump, in which case you should be more concerned.
Rob,
Last edited by Rob_DOHC; 09-07-2015 at 12:19 PM.
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Karl @ FPT (09-07-2015)
09-07-2015, 08:18 PM
#12
Regular Contributor
Thread Starter
Hey Rob,
I wrote a long article about how I tested the fuel pump here:
https://passionford.com/forum/techni...rformance.html
Not sure if I put it in the wrong place as barely anyone has looked at it! But it's quick and very effective.
I wrote a long article about how I tested the fuel pump here:
https://passionford.com/forum/techni...rformance.html
Not sure if I put it in the wrong place as barely anyone has looked at it! But it's quick and very effective.
The following users liked this post:
Karl @ FPT (09-07-2015)
09-07-2015, 10:00 PM
#14
Just taken a look. Well written and explained. For completeness with aftermarket efi you don't necessarily need a rising rate fuel pressure regulator but obviously it makes life much simpler! especially at high boost with smaller injectors as the injectors are not able to flow the required fuel at a what is effectively a lower fuel pressure (as you already know looking at the article).
Your testing completely echos what I was trying to say above (badly). At higher loads the fuel pump was drawing more current, this current would have resulted in a greater voltage drop across the series resistance (supply and ground connections/wiring).
At lower loads the voltage drop would have been far less. So had you just tested the wiring etc, using the tried and tested internet method you may not have spotted that anything was amiss with the pump and assumed the fault was else where. Was the fuel pump a straight cosworth item or an 044?
Did that make more sense? lol My point really was aimed at the fact that measuring the voltage drop across the supply for one car means nothing when applying the same basic test to another without at least knowing either fuel pressure or fuel pump current as the voltage drop changes (is not static). Naturally any resistance caused by the wiring will limit the current which can be drawn by the fuel pump also and the best method would be to suck it up and actually monitor fuel pressure as you did.
Rob
Your testing completely echos what I was trying to say above (badly). At higher loads the fuel pump was drawing more current, this current would have resulted in a greater voltage drop across the series resistance (supply and ground connections/wiring).
At lower loads the voltage drop would have been far less. So had you just tested the wiring etc, using the tried and tested internet method you may not have spotted that anything was amiss with the pump and assumed the fault was else where. Was the fuel pump a straight cosworth item or an 044?
Did that make more sense? lol My point really was aimed at the fact that measuring the voltage drop across the supply for one car means nothing when applying the same basic test to another without at least knowing either fuel pressure or fuel pump current as the voltage drop changes (is not static). Naturally any resistance caused by the wiring will limit the current which can be drawn by the fuel pump also and the best method would be to suck it up and actually monitor fuel pressure as you did.
Rob
Last edited by Rob_DOHC; 09-07-2015 at 10:06 PM.
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