Fuel regulator set up

[evilscorp]

Keep the damper, they help a lot to reduce fueling irregularities when tuning. CJM re-made their fuel rails to include oem dampers to help big power builds, stop water hammer etc.

[nissanman312]

Great info guys

Good luck with the build scobie

[jumping350]

This may just confuse matters but this is how mine is

[davey_83]

Once the desired fuel pressure has been set, always remove the fpr gauge as these over time go out of calibration. On my old SR20 I use to have a spare gauge just for setting up and one id leave fitted as a gauge in the engine bay always looks cool.

 

I take it on the VQ35 the afpr isn't vacuum controlled?

[ChrisB]

 

Whoops.. late to the party, but since you have a pic of mine..

 

Some us used the similar AAM kit originally which came with an Aeromotive EFI bypass 13129 regulator (or used to be). CJ Stage 0 uses Fuelab's 51502 (unless an alternative e.g. the Aeromotive, is specified as a slightly more expensive option).

 

Both of these have the fuel return coming out of the bottom of the regulator, with two input ports coming in at the side. One input port is normally blanked off.

 

See these install guides: (particularly the first one)

 

51502:

http://fuelab.com/wp...nstructions.pdf

 

CJ (states return to the bottom)

http://cj-motorsport...ts/fuelab-51502

 

AAM with Aeromotive regulator as an alternative

http://aeromotiveinc...-2906-0revA.pdf

 

Both are falling/rising pressure controlled from the boost/vacuum reference - you can tap it from the plenum. (NB Set the base pressure with this at atmospheric).

 

Stock VQ DE do not have ECU control over pump speed - only pump on/off by relay. The only speed change it gets is by voltage change to the battery when the alternator takes over when the engine is running not by 'intelligent control'. The ECU briefly pressurises the fuel circuit before starting, then after the engine is running keeps the relay on.

 

Stock fuel buckets have the mechanical regulator in the bucket - so pressure regulation is at pump source - very much at the input side. FI can require respectively more fuel and bigger volumes from bigger injectors, and empirically it was noticed that the open loop stock system VQ wasn't up to maintaining supply (in common with many other FI retrofits). Hence the return system which relocates pressure regulation to after the fuel rails.

 

The FI return system (as correctly stated before) is supplied by much more than it can use, so excess is vented back to the tank. As more than stock fuelling capacity is likely to be required in boost situations, a bigger pump is used (the Walbro 255l is sufficient here) to cope with sudden change and increased volume. The regulator connection is to the exit side from the fuel rail so will always keep the rails on the side of high pressure healthy supply - as also mentioned in the other post, as when the big injectors drain the rails rapidly, asking the mechanical regulator to 'catch up' supply would be asking it to react to a lower pressure in the rail - i.e. they would already drained and possibly starved. Always more is more and richer is safer (assuming not richer all the time). However, to be fair, surges are a lot less of an issue when supercharging - apart from suddenly mashing the throttle, and even then s/c is not like sudden turbo non-linear demands. The other thing is that when cruising no extra fuel will be used as the closed loop 14.7 AFR will be maintained - which is almost no different to running N/A.

 

Definitely keep dampers in the circuit where possible. They are there to help stop localised uneven flow issues and possibly fluid resonance (which some people have seen as causing flat spots at certain RPMs) which CJ went to great lengths to remove in his more advanced upgrade kits by embedding dampers directly in the rails. (V.fe rails).

 

As a footnote, I much prefer the design of the CJ S2 (parallel rails with embedded damping, bigger pipes) and later upgraded to that. The stage 0 kits work with the 'twin spur' arrangement of the stock system - which is OK and used by many, but left room for improvement.

 

[scobie140]

Keep the damper, they help a lot to reduce fueling irregularities when tuning. CJM re-made their fuel rails to include oem dampers to help big power builds, stop water hammer etc.

Cheers will do

 

This may just confuse matters but this is how mine is

Why would you do this? I'll just pretend I didn't see that pic.

 

On a serious note I've now convinced myself that the feed from the rail should be fed into the output line as that's what the gauge is measuring. Essentially regulating backwards compared to the diagram fuel lab have.

[scobie140]

 

Whoops.. late to the party, but since you have a pic of mine..

 

Some us used the similar AAM kit originally which came with an Aeromotive EFI bypass 13129 regulator (or used to be). CJ Stage 0 uses Fuelab's 51502 (unless an alternative e.g. the Aeromotive, is specified as a slightly more expensive option).

 

Both of these have the fuel return coming out of the bottom of the regulator, with two input ports coming in at the side. One input port is normally blanked off.

 

See these install guides: (particularly the first one)

 

51502:

http://fuelab.com/wp...nstructions.pdf

 

CJ (states return to the bottom)

http://cj-motorsport...ts/fuelab-51502

 

AAM with Aeromotive regulator as an alternative

http://aeromotiveinc...-2906-0revA.pdf

 

Both are falling/rising pressure controlled from the boost/vacuum reference - you can tap it from the plenum. (NB Set the base pressure with this at atmospheric).

 

Stock VQ DE do not have ECU control over pump speed - only pump on/off by relay. The only speed change it gets is by voltage change to the battery when the alternator takes over when the engine is running not by 'intelligent control'. The ECU briefly pressurises the fuel circuit before starting, then after the engine is running keeps the relay on.

 

Stock fuel buckets have the mechanical regulator in the bucket - so pressure regulation is at pump source - very much at the input side. FI can require respectively more fuel and bigger volumes from bigger injectors, and empirically it was noticed that the open loop stock system VQ wasn't up to maintaining supply (in common with many other FI retrofits). Hence the return system which relocates pressure regulation to after the fuel rails.

 

The FI return system (as correctly stated before) is supplied by much more than it can use, so excess is vented back to the tank. As more than stock fuelling capacity is likely to be required in boost situations, a bigger pump is used (the Walbro 255l is sufficient here) to cope with sudden change and increased volume. The regulator connection is to the exit side from the fuel rail so will always keep the rails on the side of high pressure healthy supply - as also mentioned in the other post, as when the big injectors drain the rails rapidly, asking the mechanical regulator to 'catch up' supply would be asking it to react to a lower pressure in the rail - i.e. they would already drained and possibly starved. Always more is more and richer is safer (assuming not richer all the time). However, to be fair, surges are a lot less of an issue when supercharging - apart from suddenly mashing the throttle, and even then s/c is not like sudden turbo non-linear demands. The other thing is that when cruising no extra fuel will be used as the closed loop 14.7 AFR will be maintained - which is almost no different to running N/A.

 

Definitely keep dampers in the circuit where possible. They are there to help stop localised uneven flow issues and possibly fluid resonance (which some people have seen as causing flat spots at certain RPMs) which CJ went to great lengths to remove in his more advanced upgrade kits by embedding dampers directly in the rails. (V.fe rails).

 

As a footnote, I much prefer the design of the CJ S2 (parallel rails with embedded damping, bigger pipes) and later upgraded to that. The stage 0 kits work with the 'twin spur' arrangement of the stock system - which is OK and used by many, but left room for improvement.

 

 

Cheers Chris i spent ages trying to find a guide like that!

I think i started to over think it when I found the fuel lab diagram with the input at the bottom which put me in doubt, Glad its all cleared up now and now got a much better understanding of the set up

I think the CJ S2 would be overkill for me as i'm only aiming for 400whp but I wouldn't rule it out for the future.

[Tricky-Ricky]

 

 

Stock VQ DE do not have ECU control over pump speed - only pump on/off by relay. The only speed change it gets is by voltage change to the battery when the alternator takes over when the engine is running not by 'intelligent control'. The ECU briefly pressurises the fuel circuit before starting, then after the engine is running keeps the relay on.

 

 

I just had a look at the manual and it seems i was wrong about intelligent pump control, so i am surprised and a little disappointed, i expected more, i know some modern engines use an ECU controlled pump to modulate fuel pressure, rather than stop/start.

 

So the VQ system relies on over pressure to supply enough fuel for various loads, and no doubt suffers fuel heating because of it, makes the likes of some of the older Vortech supercharger kits, fuel fudgers a bit of a worry.

 

As for fuel dampers i have always removed them on tuning other FI engines, as they can restrict flow on high demand, especially if set up for std power limits, which is why i would be inclined to remove the VQ item when running FI and an uprated pump, i would also disable the on/off of the pump from ECU and set to run constantly once ignition is on with a return system.

Edited February 6, 2017 by Tricky-Ricky

[ChrisB]

 

 

Stock VQ DE do not have ECU control over pump speed - only pump on/off by relay. The only speed change it gets is by voltage change to the battery when the alternator takes over when the engine is running not by 'intelligent control'. The ECU briefly pressurises the fuel circuit before starting, then after the engine is running keeps the relay on.

 

 

I just had a look at the manual and it seems i was wrong about intelegent pump control, so i an supreised and a little diapointed, i exspected more, i know some modern engines use an ECU controled pump to modulate fuel pressure, rather than stop/start.

 

So the VQ system relies on over pressure to supply enough fuel for various loads, and no doubt suffers fuel heating because of it, makes the likes of some of the older Vortech supercharger kits, fuel fudgers a bit of a worry.

 

As for fuel dampers i have always removed them on tuning other FI engines, as they can restrict flow on high demand, especially if set up for std power limits, which is why i would be inclined to remove the VQ item when running FI and an uprated pump, i would also disable the on/off of the pump from ECU and set to run constantly once ignition is on with a return system.

 

Early systems back in the nought-ies over the pond - especially those without these supporting mods were a lot more unreliable. There were stories of s/c VQ engines going bang a lot, which are far fewer in later builds.

 

Applications may vary, but there doesn't seem to be *much* heating in the tank or lines in my experience - the pump is immersed and operates against the bypass (either in stock or remote) so there is always cooling fuel flow to keep temperatures reasonably down. Friction in the pipes and circuit around the engine bay don't add much - except from heat soak perhaps if stuck in a jam for hours and cooling is compromised. Certainly I've never noticed the pipes getting particularly hot. I have an electronic pressure transducer connected to my logger/display and the only time it shows out of normal (rising) pressure range is after a long spell in traffic (e.g. 2-3h M25 monster), indicating something going on thats likely temperature wise. Perhaps a continuous max load drifter would say different? (drift.. oh the mechanical pain )

 

As it happens, I have a sneaky bypass relay on a manual switch for setting up regulation pressure - so can run the pump when the engine is not running. For normal operation, the ECU relay is fine and the fuel regulator holds primed pressure perfectly for starting purposes. There would be a fuel safety issue if the ECU controlled fuel cutoff relay is overridden, as in a crash, you *really* want the pump off. Starting in mine is first turn of the crank - literally 1 or 2 cylinders worth of ignition and she bursts into life. Priming pressure is good.

 

I have to differ on the need for dampers - the VQ can seem to suffer from flow interruption problems if they are *not* present, as some people have found in practice (e.g. a chap on here 'Mouthwash' possibly had standing waves or something at certain RPM, amongst other stories in the US - the reason CJ re-designed his rails to try and rebalance the fluid-mechanical tuning - the picture is a bit internet anecdotal though). I think I witnessed flow disruption myself as my measured fuel pressure curves were horrible and jerky until the fully damped V.fe rails went in - after that it was smooth as a baby's - although it's hard not to possibly conflate repair with observed characteristic as in the early teething incarnation of my fuel bucket, I had a bad o-ring at the bypass plug and had rough start issues all the time (as well as certain WOT fuel pressure issues) as circuit pressure incorrectly leaked away in the tank - worth knowing if new install symptoms persist.

 

All good fun

[davey_83]

When it's said fuel dampers, are these not the oe fpr's?

[Tricky-Ricky]

No fuel pulsation dampers are basically there to damp out the oscillation caused by injectors opening IE there duty cycle, personally with a regulated system i don't think they are necessary, but probably do help with an unregulated non return system.

Edited February 6, 2017 by Tricky-Ricky