Hi all..
Just ended the Single plane conversion (from Superram) and Heads swap . (From brodix 200Race Rite Heads to AFR 195 comp port) on my 396 SBC vette.
I Have a tune not perfect yet, but the car start, idles, runs and runs VERY well.
I noticed 2 VERY strange things .... One is good and the other is really strange.

I start with the strange one:
The fuel level digital level is crazy now.
The first time I used the car I was thinking to have one or two melted plug wires... In reality I was with 3 bars in the digital fule indicator , and no gas in the tank.
I used a litlle tank and I filled the corvette gas tank with only 1, gallons.
The indicator jumped to half the way.. Then started to drop as I had a hole i the gas tank..
The next day I put another 3 gallons and it jumped to 3/4 full!
I used the car for about 30 miles and I run Out of gas, with the reserve not even shown.

I alway had The fuel indicator really close to be exact. With the reserve ON , I always made a tleast 30 or 40 miles before to be pressed to search a gas station. Even with 0 (=zero) bars, I never had a "run out of gas".

WHat can be happens?? I have not touched the fuel level sender in the gas tank.... The last fuel pump swap is of 3 o r 4 years ago....

I have to say that I completely removed the old fuel line and with new custom fuel rails I have a different fuel line routing with braided lines..
I removed also the front pulsator placed in the rigid side of the original fuel line.
Can be this the problem ???
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Now the good thing (even if incredible).
I have a 700R4 unit built by PeteK. I'm proud of his work.
The unit has always performed good.
The only strange thing is that at speeds OVER 53 mph with the shifter lever in OD, letting off the gas pedal and moving the shifter lever from OD to D , NO downshift occurs.
It occurs only when UNDER 53 mph.
Example higway: 80 mph, I lift the gas pedal because there is abit of traffic. I slow the speed to 75 , I decide to put the gear from 4 to 3.
I move the selector from OD to D. Nothing happens. (i'm again in 4th gear). The car continue to stay in 4th gear. Even if I press really slightly the accelerator pedal (with the lever in D) it gains speed in 4th...
When the speed slows and go down to 53mph it select the 3rd gear. (only when UNDER 53 mph)

NOW it downshift !!!!!!!!!!!!!!!!!!! yesterday tried from 85 mph.
Now when I move the lever from 4 to 3 (from OD to D) , I have a downshift.
What can be happenz during the intake/head swap???

Thanks
-Beppe-

 

Beppe,
I would be looking at the float assembly in the tank for the fuel level issue. Maybe when you swapped out pumps it became mucked up. I have both pulse dampners removed from the fuel lines with no effects on the system.
If it is the same trans, have you re-set the TV cable since the intake swap ?

 

Thanks mseven.
I have not touched the fuel pump. I really don't know why it is acting like crazy.
About the trans , You know I'm not a newbie in vettes and trans. I tried everything to cure this strange problem. I asked to PeteK , and to Dana at probuilt too. NoOne has an answer. I tried every pressure level playng with the tV cable (knowing WHat I do.. oboiuvsly).
The assumption was that at 0 TPS the pressure was too little.
I fabricated 4 different throttle levers to have max pressure at WOT (oboiuvsly) and 4 different pressure level when the throttle was released.
Even with the pressure just a a bit less than the max (using less leverage ..letting it return less than the stock one), I always Had the strange no downshift problem.
Now I'm using the stock throttle lever of the Arizona speed and Marine TB putting max pressurw at 100% TPS and the correct preload o 0%tps.
I know that the preload of the TV cable at 0% TPS is for sure much more less than the aggressive lever I fabricated with the old Holley TB.

 

Someone with some hypotesys? some guess?...
-Beppe-

 

Did you touch or change something in the ECM ?

 

Beppe,
Knowing who built the trans and I assume it is still reasonably fresh, I am still thinking it might be tv cable related. I've have read before that if the tv cable plunger and sleeve is worn, that it can cause downshift issues. Possibly going to a different tv boost valve for improved line pressure ? I'm cerainly no trans expert, but I would think Pete might have an idea or two on this....
where is Pete ?
Mick