Originally Posted by phunk (Post 3783690)

The concern with running the Z1 second pump full time is that the driver side of the fuel tank in a Z is generally empty during normal driving, if the fuel gauge is at 1/2 or below.

This is because the factory fuel pump housing has a venturi jet pump that is recovering fuel to the passenger side of the tank so that the fuel pump can pick it up and send it to the engine. The recovery of fuel is quicker than the consumption of fuel, thus if you were to pull over the average Z on the average drive with a 1/2 tank of fuel and open both sides of the tank, you will find that the driver side is empty and the passenger side is full.

The reason the Z suffers starvation is because the fuel sloshes to the driver side of the tank on hard turns, and then there is none for the fuel pump to grab. The venturi jet pump is literally "powered by" bypass fuel leaving the regulator. So when the pump starves, the jet pump dies also. This is why a real bad case of starvation can leave you on the side of the road even with a significant amount of fuel in the tank. If you slosh it bad enough, there is just none for the pump, and the jet pump is dead due to no fuel leaving the regulator.

The Z1 kit eliminates starvation by "supercharging" the recovery of fuel to the passenger side by pumping it there with an actual fuel pump. This will make the driver side of the tank far more prone to just being entirely empty when driving the car at 1/2 tank or below, especially on the street where you will rarely turn hard enough to slosh fuel back over to it.

Electronic fuel pumps dont have a great lifespan when they run dry because the gasoline is what cools and lubricates them.

So if you DO use your Z1 kit on the street, I would highly recommend you put a toggle switch on it so you can turn it off. On the track it should be fine as it will constantly get sloshed fuel. On the street, it will run dry for long period.

The CJM RRP is a surge can system that operates under an entirely different principle and it is normal and required that both pumps run all the time.

Originally Posted by Hotrodz (Post 3783701)

Thank you sir for the explanation as you have taught me something new and I appreciate your insight and experience. :tiphat:

Originally Posted by cv129 (Post 3783730)

Wow, I was seriously considering Z1 kit for the price, but Phunk’s explanation pulls me back to the darker side lol.

Originally Posted by zmanelite (Post 3783733)

A toggle switch could be made for Z1 and run it for track only

Or maybe just run stock pump a Y and a extra line with a Hydramat to passenger side

Originally Posted by Hotrodz (Post 3783668)

I drive mine as a sometimes daily driver. I'm not sure what the issue is other than fuel economy which I have never been concerned with, because it is a sportscar lol. What part of not being a real fix are you speaking of. There isn't anyone in this thread that has said their issue with fuel starvation was not eliminated with the kit. You are in the track section so maybe people who don't track aren't committing because they have found a fix and moved on.


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Originally Posted by DarkJak (Post 3783900)

And that my fuel lights have read 1/4 tank lower than they actually are ever since the install. (maybe also user error).

Originally Posted by Tractionless (Post 3783841)

Did you happen to read the thread I linked of my issue? I’m not sure that it’s fuel starvation to begin with. That’s just what most members default to when the engine quits on the Z.

Car sputtered to a stop 1500’ after a 500’ right turn on the street which I took moderately at best and with 7 gal. in the tank. Suitcase in the back didn’t even shift. There’s more details in the actual thread.

I came proactively seeking starvation solutions one of which is the be all end all; however, IMO overkill for a street only setup and the other while no failures in the track cars it was meant for leaves ends untied for the street.

Originally Posted by Hotrodz (Post 3783905)

I did read your thread and I apologize if I was being harsh as I was not totally grasping your situation. I get it, you don't want to spend more money than you need to resolve your issue. From all the threads I have read on this issue regardless of track or street use only it seems there is a wide range between those that have issues and those that don't. I never experienced fuel starvation before hitting the track, even after boosting. Phunk kit was the first to successfully and reliably deal with the issue then came along the hydromats. For now these are the only two good options and one is more expensive than the others and deals with the issue you brought up and I got educated on and so you just got to decide which one is best for the money or live with the issue. Many street only folks have though it was worth buying the rrp system. I just decided to go a different route because of the build I have at the time I was looking to resolve my issue.

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Originally Posted by Tractionless (Post 3784205)

Thanks and no worries; I didn't feel you were being harsh.

I've decided against the pre-packaged starvation kits at the moment.

Instead I'm replacing the entire OE fuel pump assembly with a new one due to the sound of my fuel pump motor prime changing during the issue. I have a feeling the fuel pump motor is on its way out.

I'm currently debating using a Hydramat in lieu of the OE pickup sock but trying to find out the O.D. of the OE pump inlet as Holley only offers 11mm for such a configuration.

Originally Posted by Tractionless (Post 3784205)

Thanks and no worries; I didn't feel you were being harsh.

I've decided against the pre-packaged starvation kits at the moment.

Instead I'm replacing the entire OE fuel pump assembly with a new one due to the sound of my fuel pump motor prime changing during the issue. I have a feeling the fuel pump motor is on its way out.

I'm currently debating using a Hydramat in lieu of the OE pickup sock but trying to find out the O.D. of the OE pump inlet as Holley only offers 11mm for such a configuration.

Originally Posted by Rusty (Post 3784217)

If you re replace the whole assembly. Get phunk's billet top hat for it. Then you don't have to worry about it breaking.