1998 Z71 Build

[Supercharged111]

My newest thought is I'm overheating my fuel through the factory metal fuel lines, they run pretty close to my long tube headers. Since I have to run AN tubing anyways for the flex fuel sensor, I'm going to route it as far away from the exhaust as possible, with some heat shielding to boot. See if that fixes the problem

How long of a run of line is near your headers?

 

[Awest623]

How long of a run of line is near your headers?

It's been a minute since I've been under that part of my truck. If I had to guess around 18" inline with the headers, plus the convective heat that would come off the headers when the truck is idling or parked. The headers and fuel line follows almost the same path with about 6" separation. I'd have to check to be sure

 

[Supercharged111]

It's been a minute since I've been under that part of my truck. If I had to guess around 18" inline with the headers, plus the convective heat that would come off the headers when the truck is idling or parked. The headers and fuel line follows almost the same path with about 6" separation. I'd have to check to be sure

I wrapped mine, but only where it crosses directly over the header. I never thought much of the rest as there is that 6" of separation which is fine if you're moving. You should put a fuel temp sensor in there and report back so I don't have to.

 

[L31MaxExpress]

My dramatic fueling shifts were all IAT related. I ended up disabling the complex blend option on mine.

Also when you tune be sure that your purge solenoid is not active. The purge system puts my fuel trims between -5% and -10% when it is active.

 

[Awest623]

I wrapped mine, but only where it crosses directly over the header. I never thought much of the rest as there is that 6" of separation which is fine if you're moving. You should put a fuel temp sensor in there and report back so I don't have to.

Ya everything goes back to normal as long as the truck is moving. But sitting idle slowly raises the afr 5-10%, and the hot starts peg the gauge.

 

[Awest623]

My dramatic fueling shifts were all IAT related. I ended up disabling the complex blend option on mine.

Also when you tune be sure that your purge solenoid is not active. The purge system puts my fuel trims between -5% and -10% when it is active.

My IAT reads accurate even after sitting. No heat soak. And I've have the complex blend disabled for about a year now.

I monitor the purge valve on every log.

 

[L31MaxExpress]

Ya everything goes back to normal as long as the truck is moving. But sitting idle slowly raises the afr 5-10%, and the hot starts peg the gauge.

There is an afterstart enrichment table and enrichment decay table that I have only seen populated on the 4.3L and the LS in the P59s. There is an 03 4.3L Van file in HP Tuners repository. You can add fuel at higher IATs on restart if you want.

 

[Awest623]

There is an afterstart enrichment table and enrichment decay table that I have only seen populated on the 4.3L and the LS in the P59s. There is an 03 4.3L Van file in HP Tuners repository. You can add fuel at higher IATs on restart if you want.

Yup. Got a new file ready to be flashed. Bumped the enrichment up and dropped the decays to what I believe is the correct to take 270 seconds to completely decay.

 

[Awest623]

My order from summit racing came in early so I installed the flex fuel sensor and a new fuel level gauge today. Only took a couple pictures, one of a mockup of the fuel lines, a picture of the flex fuel sensor installed, and a before install of the fuel level gauge. I plumbed it with a 3' -6 AN line with appropriate adapters in between. I haven't wired up the flex fuel sensor, got too late and cold in the garage. I know it doesn't look like it but that is a new inline fuel filter as well, it's been bouncing around in my toolbox for a couple years

No leaks on priming or idle. I'd call that a win!

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[Awest623]

Wired up the sensor today.

I'm having the issue that @L31MaxExpress described. Fuel composition sensor only works when crank lo res is set to 0. Setting it to 1 keeps the reading at last known value. That's unfortunate. Hopefully one of us can come up with a fix.

For the sensor ground I used some threads in the frame where a fuel line support used to be. (All that red you see ain't rust, it's South Carolina red clay. Impossible to get off short of wire wheeling the whole frame.)

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I did use shielded wires for the install. Way overkill, especially for a digital signal. But I had the perfect amount left over from the fuel level gauge to make a a decently clean run

(This is before I connected everything up)

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