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Rising Rate fuel regulator


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Need to replace this on my 3.9 running a flapper efi. So as the setup is not stock I have seen recommended a rising rate regulator. Does anyone know any good makes or good sources for these?

I have seen a make (3 letters?) that has a dial you screw in to adjust the pressure that seem popular.

Any pointers?

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Need to replace this on my 3.9 running a flapper efi. So as the setup is not stock I have seen recommended a rising rate regulator. Does anyone know any good makes or good sources for these?

I have seen a make (3 letters?) that has a dial you screw in to adjust the pressure that seem popular.

Any pointers?

I have one off the Eales, I'll post up a pic and Mker later today, from memory it was around £60+,

.............so have a think of an offer :lol:

If you do get one make sure its the HP one for an EFI and not a carb !

Nige

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post-22-1185870027_thumb.jpg

Here it is Malpassi adjustable HP Fuel regulator

IMHO you don't need Rising Rate you just need to have the pressure set within the correct ranges, some std PRVs are fine, others are not, they seem to vary, suggest before you spend money you measure what the pressure is at tickover on you V8

If you haven't got the Kit you could whiz up and use mine at the weekend ?

You may find you don't need to spend any money !

Why do you think this isn't fited to mine currently :)

Nige

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IMHO you don't need Rising Rate you just need to have the pressure set within the correct ranges, some std PRVs are fine, others are not, they seem to vary, suggest before you spend money you measure what the pressure is at tickover on you V8

If you haven't got the Kit you could whiz up and use mine at the weekend ?

You may find you don't need to spend any money !

Nige

Thanks for being so quick Nige.

Issue is that I have chronic overfuelling (stuttering, and clouds of rich black smoke) but vehicle still runs. Will probably put a thread up about it, but it is intermittant and I have tested out all efi electronics and seem OK. So have now moved to the mechanical stuff. Because it's a 3.9, I need around 42 psi in the fuel rail (I also dented the other stock one trying to get it off :rolleyes:), so figure now is a good time to upgrade. I am assuming that AFM and ECU are OK because when it wants to it runs as sweet as a nut. This is realling hacking me off as it's taking far too much time to sort out.

I thought rising rate were good for flapper upgrades because it stops them leaning out on acceleration and at higher revs ('cos no Lamda to say more fuel).

Kind offer to come and use your kit, may take you up on it some time, but need to sort this out and then the bulkhead for MOT.

How does this one attach to the bracket as it seems a different layout? You are correct, I have spent far to much on this vehicle already, how does £20 sound (assuming OK for the job)?

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Been here before - rising rate regs are just a bodge, by increasing the pressure under load you are getting more fuel in than the standard ECU expects. Unless you're pratted about with the engine the stock reg with the stock ECU should be giving you the correct amount of fuel.

A better investment would be to run redex injector cleaner through it for £5.99, if your injectors are a bit gunky after all these years they will flow more when un-gunked.

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Unless you're pratted about with the engine the stock reg with the stock ECU should be giving you the correct amount of fuel.

A better investment would be to run redex injector cleaner through it for £5.99, if your injectors are a bit gunky after all these years they will flow more when un-gunked.

My flapper is from a 3.5, so I was under the impression that I needed to up the pressure and then tweek the AFM to produce 2% CO to account for engine volume. Isn't stock pressure around 32 -35 psi?

Will certainly be putting some cleaner through it (probably Seafoam :lol:) to get rid of all this carbon soot I am generating trying to sort the *bleeper* out.

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This sounds like more of an EFI problem than needing a rising-rate regulator. Sort your car out THEN decide if you need bling bits or not, you could end up masking a different problem otherwise.

Your injectors will work at 37 or 42 PSI, I believe the stock FPR's are the same for flapper and hotwire, indeed most Lucas 14CU systems seem to run the same pressure (37) although Bosch do spec the injectors for 42psi. The FPR's function is to regulate the fuel rail pressure relative to the plenum vacuum so that the amount of fuel injected per squirt is constant.

As for changing pressures / tweaking AFMs / etc etc if you start a diagnosis thread and post up all the stuff you're running and what the problem is then we can get to the bottom of what is causing your problem rather than blindly tweaking thing, spending money and listening to the Haynes Book Of Lies :rolleyes:

Flapper and Hotwire are MAF (Mass Air Flow) systems so you should not need to tweak them to compensate for a larger engine.

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Fridge, couldn't agree with you more about the mucking about and adding 'bling' bits. As per our discussion before, I just want to get it up and running as is. Trouble is, I dented the one that was on trying to get it off (which I assume hasn't done it much good), so will need to replace anyway. Thought may as well get a decent one where fuel pressure is a known quantity and can be diagnosed more easily in the future.

Not disputing your wisdom :lol:, but have seen the recommendations for slightly tweaking up the fuel pressure and AFM on a 3.9 upgrade in several places. Guess an adjustable regulator would at least give this option. Rest assured won't be touching the AFM until issue (now posted on seperate thread) has been sorted.

Cheers.

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I have a Rising rate here for a flapper (yes, it came from RPI) that I have set to the correct pressure ………….. they are supposed to be pre-adjusted and this one was running 55psi.

Make me an offer and its yours …….. ;)

Raising the fuel pressure will mean that the injector puts in more fuel for any given injector opening time ………….. it was a work around for folk that couldn’t access the fuel map…………… but it does have serious drawbacks,

If you exceed the normal injector working pressure, then they drip fuel causing backfiring and also popping in the exhaust.

The increase in pressure alters the fuel map in a linear manner ………… you don’t really want that.

The high MAP setting of the regulator will also be higher, thus injecting more fuel at tickover……

:)

Ian

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