First off, I have a 85 12A motor/electronics adapted to a type 1 VW transaxle, this is a sand rail.

A bit about the car: street port 12A, dizzy with A/M plug wires, Weber IDF40 carb, Mallory fuel pump/regulator (psi @6-6.5), Garret M24 Turbo (runs 10-12 psi), fresh oil, fresh coolant. No intercooler (yeah I know I need one. I need a wideband O2 also). Note* Car will not idle if fuel pressure drops below 5.8ish.

I start up, idle, light revs, start off slow for 1/4 mi. Turn around, drive back home a bit quicker. Car is running great, nice idle around 850 rpm. Head back up the street, hit boost in first, shift into second, boost, off boost, car starts running badly, won't stay running unless I work the gas staying above 1500 rpm. Car was running for a total of maybe 10 mins. Hour later, car will still only run if I work the throttle. Fuel pressure wont go above 5.2 psi. Pressure started out @ 6-6.5 psi. Car only got to 160 F via brand new autometer temp gauge.


Same thing happened to me about 2 weeks ago, but I drove for close to an hour before the car died. When it did it this time, I was idling down a slight decline and it died. Had to work the throttle keeping about 1500 rpm to stay running once again. Still wouldn't idle when I got home 45 mins later. Fuel pressure dropped to 4 psi.

Today, before the first scenario took place I had the batter charged, made sure I had fuel, took the fuel regulator apart and looked for damage (looked fine, set it at 6.3 psi), and tested the battery (12.8 V with car off, 13.3-13.5 V car running).

Note*
Turbo is not wrapped, sits 3/4" under aluminum intake manifold. Intake mani and carb get almost hot.
Car is difficult to start once it dies. Have to work throttle, cycle motor for 4-5 sec.
I can't figure this out. Nothing is obviously wrong to me. The fuel PSI drop puzzles me. Not sure why the PSI went back up today unless me taking the regulator apart reset something.

Help??

 

i see a few possible things here.
1. i'm not sure if a 40 mm is large enough to feed your setup adequately, even with the forced induction. hopefully someone with more relevant experience might weigh in.

2. you should probably look into getting a rising rate pressure regulator.

3. what is the output volume of the pump you have?