Z1 Anti-Fuel Starvation Kit and Fuel Readings
 

I recently had the shop install one of the anti-fuel starvation kits from Z1 and had some odd fuel indications while driving it back to the house.

1. Pulled up to the pump on practically fumes (zero dots on the gauge). Filled up the tank and displayed half tank. This is not uncommon to see in the forum. It just needs an adjustment on the fuel level sensor. The odd thing is that the fuel started to go UP as I was driving, eventually showing full tank before creeping back down.

2. The current fuel efficiency (MPG) was displaying over 50 mpg during highway speeds.

3. The range was showing 600+ miles until empty.

4. The information may be relevant: The shop was also installing the SOHO Supercharger kit while they installed the anti-starvation kit.

Has anyone come across this issue? Any information would be really helpful. I'd like to take care of any gremlins before they cause bigger problems or multiply.

Thanks!

Product Link

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One of your float arms may have been bent. You have 2, one on each side of the tank. That is the most common issue when folks upgrade to such.

You running different injectors?

A bent float arm doesn't seem to explain why the indication started to go up during the drive. Although, that's the first thing I'll have em check.

The kit came with bigger injectors. Would a different electrical flow to that make a huge difference on the readings?

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"It just needs an adjustment on the fuel level sensor."

What adjustment is typically needed here? I have the half-tank reading issue.

I've had the level go up on me mid drive too, and I just figured it was due to irregularities between the two halves of the tank + fuel sloshing around from one half to another making the sensor calculations inaccurate.



On high MPG readings, my memory is that it's due to moving to larger injectors with F/I installs and the car's calculator not accounting for the additional fuel used with each cycle of those injectors over stock.

See, never had this issue until the current build and I know I've had sloshing with some of the driving on the track. I had fuel starvation issues but not oscillating fuel readings.

From what I read in the forums, they go back there and basically double check their work. I haven't gone in on the tank myself so I couldn't say, first hand. I had a shop work on it to avoid these types of issues.

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The fuel mileage is based off of injector dwell time. Bigger injectors need less dwell time for the same flow of fuel.

On the fuel level. A couple of things come to mind. A bent float arm. Or the Z1 mat is not lying flat on the bottom of the tank and is hitting the float arm. The hose from the mat to pump maybe touching the arm. If the driver side canister is not installed right. It maybe turned and the float is hitting the front baffle.

Thanks for the replies, Rusty! Is there anything to be done to get accurate fuel readings again?

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You are going to have to go into the tank again. I would run the fuel level down in the tank. Start on the drivers side. Remove all of the nuts that hold the top on the tank. Slowly lift up the canister a couple of inches. Using a flashlight. Try and see where the arm is pointing to and if anything is near it. It should be pointing towards the center of the tank. Next, take a bent coathanger and lift up on the arm. It should move freely. Look and see where the hose is for the mat and fuel fuel is. Shouldn't be near the float arm. If everything checks out. Move to the other side and do the same thing. I know my way around with phunk's RRP kit. The Z1, not so much. I don't know exactly where the mat is placed on the drivers side and the route the hose is run from the mat to the pump. The only other thing that I can thing of. Is a bad sensor on either side. You have to get into the manual for that. There a is a chance that they ruined a sensor. But I think that might be low on the totem pole.

Good deal. I'll talk to the shop about the fuel level sensors. Anything to be done about the fuel consumption reading or that's just what we get now? I'll hit up SOHO Motorsports who makes the kit and see what they say.

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I'm not sure if ECUTEK has anything that corrects mileage, but it might since you can create custom mappings.

...how is the tire pressure?

I switched wheels and haven't gotten these ones reprogrammed. Much better now, though.

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I've been having the same problem. I had the kit on for about 3 months now and all was good. I did take the car for a cruise through the canyons last night and was kinda pushing it. I had at least 5 fuel cuts during my 1 hour drive. Very frustrating
As far as the sensor goes, mine was similar. My gauge doesn't go lower then 1/2. 1/2 being empty... I wasn't honestly worried since I don't do a very long trip. Some have told me a bad sensor and also the bent arm too... I had my friends dad do the install for me lol

I'm starting to regret getting this kit!! I was told by Z1 that they used this setup on their track car and this kit "solved" the fuel starvation, I thought it was a no brainier.. guess not.

So, I took the car to the track yesterday. No fuel starvation issues. Fuel gauge gotta from 3/4 to empty. I have to dig into the fuel tank again and check the arms. Likely culprit is that it's catching on something giving inaccurate readings.

The most important thing I learned yesterday is that I can only do two laps before having to pit for cool down.

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I know this is an old thread, but any update on what the problem was?

I installed this Z1 kit on my G37 2 weeks ago. I barely drove it after install until track day this past weekend. It was a CCW layout so not too many hard right turns and the starvation kit probably wasn't too necessary, but my fuel gauge would just drop to completely empty while racing, even when there was plenty of fuel in the car. This is so scary. But then the gauge would randomly start working again (not sure even the reading was even correct) and then go out again when it felt like it. Towards the end of the day when I was running around what I guessed to be a quarter tank, the tank read empty and never came back on. I can't be having no reading. The purpose of this kit was to be able to allow me to race under half a tank without fuel cutoff to save weight. But I can't optimize my fuel weight if I never know when I'm going to run out of gas. Getting towed off the track isn't cheap.

I opened up the tank the next day to check out what was going on. My Lever Arm Sensors had plenty of room to move freely, nothing blocking them. But I noticed that the passenger side (with main pump) was completely full of fuel while my drivers side was bone dry empty. I guess the kit was doing its job, but its causing too many more issues.

I called Z1 to ask what they knew about this. They said that they will often install this kit with a "relay or switch" but were unable to tell me any of the details about it. They also told me I probably shouldn't have the starvation pump running if its not pulling any fuel. But yeah, no solutions offered. So much for an "all in one kit" that needs unknown additional equipment to work properly.

Then I called Specialty Z because they just tuned my car after I installed this kit and my E85 conversion components. They said that if the lever arm on only 1 side of the tank reads a completely empty tank, even if the other is full, the computer will freak out and tell you the tank is empty. Makes sense. So far, more helpful than Z1. They also told me that when they install this kit, they don't wire it to the main fuel pump (contrary to Z1's instructions). Instead they wire the starvation pump all the way to the front of the car using a "Spal Relay kit" ($70). They said that with this kit, you can turn off the starvation pump when you're not racing so that the tank evens out and the pump isn't pulling air. I'm not much of a wiring guy, and the original wiring for the starvation kit was already a bit out of my comfort zone, so there's no way I want to mess with anything like this. Its just crazy to me that Z1's kit is dysfunctional like this with no mention of additional equipment necessary to work properly.

So I've provided the info that I found out. Do you guys know any other solutions besides wiring to the front of my car? Is the OEM metal tube that runs from 1 side of the tank to the other supposed to even out the tank when it sits overnight?

Interesting. I had the same question to Z1 when I ordered the kit back in 2020. They said "the anti-starve kit acts like a surge tank and pulls fuel from the other side of the tank to fill the basket where the pump is housed. Eventually you will run the second pump dry but you would have to be quite literally on an empty tank to run the hydramat dry. If you street drive the car as well you can wire the secondary pump to a switch to only be used on the track."

No problems for me since the install, but I did install the CJM top hat at the same time.

I also recently got the Z1 kit installed. Also had some weird readings after a track event. I was assuming the lines could have moved in the tank and held up the reader. Took it back to the shop and they were able to fix it. I hope I dont see anymore issues moving forward.

And what exactly did they do?

They told me the lines had moved. So they zip tied it. Its reading fine so far. So hopefully it dont have any more issues.

I’m also having fuel level reading issues after I messed with the pump assembly. Gotta pull the pump assemblies out and zip tie things properly.


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