1972 Granada Mk1 coupe build - putting on miles… 21-05-2024

[eurogranada]

Jul 18, 2023 11:24:42 GMT kevins said:

Those plastic ones are designed for the flow rate of a carb usually with no or a very small return flow, also Carbs tend to damp out the peak flow demands. I suspect even a new one might be quite a significant restriction,I would try replacing it with a fuel injection filter and see what effect on flow it has.

I’ll try and find out by eliminating it as a final test.

[eurogranada]

Just a very quick question...

I received my lockable fuel cap, but to me it does not look vented in any way though I specified that when ordering.Seeing plenty of overflow evidence from the few drives without a cap means I don't want to return and reorder. On my previous fuel cap I had drilled a small hole, but I did feel that even with 2,5mm diameter, this would make the car smell.

So if i need to drill a hole again, how small may it be?

[kevins]

They are usually tiny, I'd estimate around 1mm.

[therealpinto]

There is "no" real flow in the vent hole so yes, it can be small. But no matter how small, you will get the petrol smell.

The only "solution" is using a charcoal canister on the vent line.

Gustaf

[davidno1]

Hello,
I haven't really followed everything that you have tested so far, but I don't really understand what sort of fuelpump you have? Does the fuel pressure drop on high load?

Or have I got everything mixed up? I understand the problem too be that you don't get enough fuel?

I have a hard time to believe that the size of your fuel lines is an issue. Standard cars with more power than what your car is making doesn't have big fuel lines. It sounds like it is the pump that's the fault. If you don't get more than ~60 liters/min on the return, I would think that that's your problem.

Something positive: I think that you have built a very nice car! I also know the feeling that you have when battling this kinds of problems, hang in there, you have come so far already!

Best regards,
David

[eurogranada]

Jul 19, 2023 16:11:57 GMT davidno1 said:

Hello,
I haven't really followed everything that you have tested so far, but I don't really understand what sort of fuelpump you have? Does the fuel pressure drop on high load?

Or have I got everything mixed up? I understand the problem too be that you don't get enough fuel?

I have a hard time to believe that the size of your fuel lines is an issue. Standard cars with more power than what your car is making doesn't have big fuel lines. It sounds like it is the pump that's the fault. If you don't get more than ~60 liters/min on the return, I would think that that's your problem.

Something positive: I think that you have built a very nice car! I also know the feeling that you have when battling this kinds of problems, hang in there, you have come so far already!

Best regards,
David

Hi David,

Thanks for your compliments and for joining in!

A quick recap: I have a dual fuel pump setup. I use a low pressure (supposedly) high volume pump at the fuel tank end that supplies a swirl pot at the front of the car. This is setup as a feed and return so when the swirlpot is full, excess goes back to the rear fuel tank. From the swirl pot I have a high pressure efi pump feeding the engine and returning to the swirl pot. So basically two circles that share the swirl pot. The high pressure circuit is very capable of feeding the engine and has 8mm lines as the thinnest cmponents. The low pressure circuit has 6mm lines that in reality measure an ID of 5,5 mm at best. But during one of the few very hot weekends we had, I had fuel delivery issues.

Testing revealed a very hot fuel pump and swirl pot. The engine bay is pretty hot environment with a cosworth BOB engine anyway, but a lack of flow between the swirlpot and rear tank was found (only 450ml a minute!), which meant the fuel heated up too much as the same fuel was constantly recycled. Flow tests showed that with a fresh clear fuel filter for low pressure applications, the flow had doubled again to 850ml. Ever since the fuel pump temp has been a lot more normal, warm but not hot like before (you couldn't keep your hand on it then). So I may not even have a problem anymore as I had never had any problems with this in the 7 years to date that I'm running this combo. So it's not that the fuel pump experiences a pressure drop, it just does not seem to generate the expected flow (this particular model should flow 120L/H the supplier verified for me).

Still, ever since I've been paranoid about getting stranded on the motorway again, as I had some less than ideal places where I had to stop. Hence the activities and discussions on what all could be the cause. I figured it was due to line size, just not able to get the right volume flowing. In a final effort I removed the restrictive connectors, which turned out not to be very restrictive as the fuel flow remained almost the same. I can test a couple of things still: removing the filter altogether for one, which is relatively easy to achieve. Another fuel pump as a second thing.
At first I felt that if the elimination of the fuel filter would not improve the flow, I should up the line sizes, but I have to say that I'm leaning more and more towards buying a better/new pump. If a new pump still does not generate the wanted flow I can always up the line size afterwards. I also like the suggestion someone made before of using a second efi pump to feed the swirlpot, that will definitely mean a return flow will start running, as it is a lot more quiet than the current type. But the drawback for me is that the inlet of that pump takes a huge line 12mm at least if memory serves me and the tank output is only 8mm. The output side can take 6 as well as 8mm depending on the banjo used.

So maybe a good question to ask now is what would you guys do: Buy a better/new high volume low pressure pump and see if it helps or adapt somehow and use an efi high pressure pump (which I have lying around)?

[westbay]

Hi Alex

How do you draw fuel from the tank ? i.e is there a pump immersed in the tank or is your low pressure - high volume pump mounted external to the tank?

I thought all Ford scorpio tanks had an immersed pump with filter and are high pressure ...

Is the fuel pressure regulator , on the fuel rail, good ?

[eurogranada]

Jul 20, 2023 8:10:02 GMT westbay said:

Hi Alex

How do you draw fuel from the tank ? i.e is there a pump immersed in the tank or is your low pressure - high volume pump mounted external to the tank?

I thought all Ford scorpio tanks had an immersed pump with filter and are high pressure ...

Is the fuel pressure regulator , on the fuel rail, good ?

As I'm using the Granada tank, the pump is external to the tank. This was the same on the MkI scorpio's. I cut the whole mounting plate and pump filter combo from one.

The pressure regulator on the fuel rail seems fine, that is, when there is fuel to flow the engine is getting it even on what acceleration etc. And the engine runs fine, just not when the fuel got so hot.


BTW: I was able to determine (form the supplier) my high volume pump should be able to flow 120l/h so with less than a liter a minute it is not flowing as it should for sure.

[sebastiaan]

Hi Alex,

You're almost there. If at all possible, try to re-run your low pressure flow test with the small filter removed. Those aren't really suited for high flow applications as they have a relatively small filter area. So replace with a piece of (8mm?) pipe and re-run the test to see if your problem is indeed the lines or the filter.

For your 120l/h and a flow velocity of 2 m/s (rough guideline), you'd need a 4.6mm ID line. Your 5.5 ID gives a flow speed of around 1.4 m/s so "should be OK". So try without the filter first and see if that helps. If not, look into another pump indeed, or upgrading the lines. But seeing how sensitive the flow was to the switch from a dirty to a clean filter I'd hazard a guess that it (still) is a relatively large flow restriction.

[eurogranada]

Jul 20, 2023 9:39:27 GMT sebastiaan said:

Hi Alex,

You're almost there. If at all possible, try to re-run your low pressure flow test with the small filter removed. Those aren't really suited for high flow applications as they have a relatively small filter area. So replace with a piece of (8mm?) pipe and re-run the test to see if your problem is indeed the lines or the filter.

For your 120l/h and a flow velocity of 2 m/s (rough guideline), you'd need a 4.6mm ID line. Your 5.5 ID gives a flow speed of around 1.4 m/s so "should be OK". So try without the filter first and see if that helps. If not, look into another pump indeed, or upgrading the lines. But seeing how sensitive the flow was to the switch from a dirty to a clean filter I'd hazard a guess that it (still) is a relatively large flow restriction.

Yes, that test I will do this weekend as it is pretty straight forward!

"But seeing how sensitive the flow was to the switch from a dirty to a clean filter I'd hazard a guess that it (still) is a relatively large flow restriction." This is why I'm now more thinking about replacing the fuel pump. Only question is with what? The 120l/h one I have is considered pretty high volume. I haven't yet investigated seriously but a quick glance also shows many versions from 60-105l/m. Your math is very welcome, this shows that it is probably more worthwhile to do something about the pump than about the lines.

[westbay]

After a coffee and biscuit fueled search ! - I notice you have treated the tank for leaks, is the product E5/E10 'safe'? and secondly I notice that your tank pickup pipe has a (simple) filter on it - I suggest you take this out and check it's clear ...

The pump (long shot!) - does it have any filters built in ?

[eurogranada]

Jul 20, 2023 11:33:16 GMT westbay said:

After a coffee and biscuit fueled search ! - I notice you have treated the tank for leaks, is the product E5/E10 'safe'? and secondly I notice that your tank pickup pipe has a (simple) filter on it - I suggest you take this out and check it's clear ...

The pump (long shot!) - does it have any filters built in ?

Yes, the tank is coated with an Ethanol proof product. The coating is stil looking awesome. Last time I had the sender out the filter was clear as new (only slight discoloration from fuel). This because the tank itself is simply very clean inside.

Also, when I changed the filter recently, well, the fuel came pooring out quite happily. That was a very steady and fast flow!

This pump has no filters, hence the carb/low pressure filter between tank and it.

Thanks for playing!

[westbay]

[eurogranada]

Well, quick and dirty:

With the filter removed and the gas cap off I now had a fat liter of flow in one minute.

With the gas cap on, it was exactly one liter in one minute.

I’m still not sure if my fuel cap is vented or not but I’ll take it for a drive and see if it hisses after a bit of driving.

I think though, that for now the total improvement from 400ml to a liter is good enough to try and see how the car behaves…

If I do still get in trouble on a hot day, I’ll update the pump.

[kevins]

1L/min is just about what it would consume at full power, driving at normal motorway speeds it will only be using something like 30 or 40Kw, so in Normal driving you have at around 4 times the flow the engine will be consuming going through the swirl pot, I think that will be fine (unless you plan to take it to Germany and do a Vmax run).

[davidno1]

One more question: The swirl pot, is it actually a swirl pot where the fuel flows "in the radius of the tank" to make the air in the fuel go away, or is it a catch tank to make sure you don't loose fuel pressure during hard cornering when/ if the fuel pickup tube gets uncovered?

/David

[westbay]

Hi Alex
Well done re the filter - love a quick fix !

HAve you checked the vent valve (sometimes called a 'roll-over valve' ) on the tank? I don't think you need to drill the cap, you'll definitely smell fuel if you do .

[eurogranada]

Jul 21, 2023 17:49:40 GMT davidno1 said:

One more question: The swirl pot, is it actually a swirl pot where the fuel flows "in the radius of the tank" to make the air in the fuel go away, or is it a catch tank to make sure you don't loose fuel pressure during hard cornering when/ if the fuel pickup tube gets uncovered?

/David

It’s sold as both catch tank and swirl pot but it’s just a small rectangular aluminium box with 6 ports.

[eurogranada]

Jul 22, 2023 10:45:49 GMT westbay said:

Hi Alex
Well done re the filter - love a quick fix !

HAve you checked the vent valve (sometimes called a 'roll-over valve' ) on the tank? I don't think you need to drill the cap, you'll definitely smell fuel if you do .

There’s no valve present as far as I’m aware. It had a high port on the tank that connects to a high port on the filler neck to vent while tanking. Hence the need for a vented cap…

[sebastiaan]

Jul 21, 2023 10:58:20 GMT eurogranada said:

Well, quick and dirty:

With the filter removed and the gas cap off I now had a fat liter of flow in one minute.

With the gas cap on, it was exactly one liter in one minute.

I’m still not sure if my fuel cap is vented or not but I’ll take it for a drive and see if it hisses after a bit of driving.

I think though, that for now the total improvement from 400ml to a liter is good enough to try and see how the car behaves…

If I do still get in trouble on a hot day, I’ll update the pump.

Great news! Now get out there and drive the wheels off the thing! Sorted! :-)