I'll try to keep this brief. During the winter months the I installed the following on my car.
- New Edel. Perf Intake
- New holley mech fuel pump with fuel pressure gauge <--important to problem.
- New Edel. Victor Jr. Water pump
- Spal electric fan with temp. sensor
- Griffin rad.
- new hoses everywhere.
- oil relocation kit with dual filter.

NOW, I started the car for the first time. and got the following results. ALL AT IDLE ON THE DRIVEWAY. 900rpm revving to 3000rpm, timing 10 adv. base timing.

COLD
- Temp 150 deg
- Oil pressure 70lbs (using Mobil 1 trisynth. 10W30
- Fuel press. 7 lbs
- Vac 15

WARM/HOT
- Temp 195deg fan turns on. And turn off at 190deg. Fans turns off too early BUT that's because the sensor is on the intake not on the heads. (I fix soon enough with a manual switch)
- Oil pressure 30 lbs
- Vac. - 15
- Fuel pressure went down to 6, then 5, then 4,3,2 and right down the ZERO?! I tapped the gauge and no response.

PROBLEM: Car still idling fine, give it gas, running excellent no problem, but fuel press. gauge still reads 0lbs! No fuel leaks anywhere....seems like the hotter the car got the lower the pressure got.

I did some more investigations on when the problem is occuring. It seems that the pressure is fine when car is cold (145-170) as the engine temp. increases (175-195), the pressure drops, as I stated before, to zero. I checked the float level, I adjusted air/fuel to the highest manifold vacuum and idle as well. After that, I throttled the engine to 3000rpm and no change.
I'm stumped! http://www.chevelles.com/forum/frown.gif


BTW, these are all mechanical gauges, it's a mild 454. Did I miss anything?
Any feedback would be appreciated.
Thanks.

Definitely sounds like you have vapor lock on the lines. Make sure all the fuel lines are away form heat sources, especially headers. Install one of those cheap clear filters, and you will probably see bubbles rising up.

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Daily driven 70 Malibu - Vortecs mild port/polish - 350 bored 40 over, mild/hot cam
SupVic Intake, TH-350, 3.08 gears, dancing Chihuahua on the package shelf

If it is vapor lock, it is pretty easy to troubleshoot. Watch your pressure gage while you pour cold water on the pump. If it comes back up in pressure, then it is vapor lock. If you used RTV to seal the pump to the block, this will allow heat from the block to affect the pump. A good thick gasket is preferred here as an insulator.

<BLOCKQUOTE>quote:</font><HR>Originally posted by JWagner:
If it is vapor lock, it is pretty easy to troubleshoot. Watch your pressure gage while you pour cold water on the pump. If it comes back up in pressure, then it is vapor lock. If you used RTV to seal the pump to the block, this will allow heat from the block to affect the pump. A good thick gasket is preferred here as an insulator.<HR></BLOCKQUOTE>

I am going to give that a try. I used a gasket and RTV combination for this. I do have a clear filter I will use as well. Do you recommend wrapping the rubber hoses going into and out of the fuel pump with cool tape? Or do you think this would be waisted effort?

Thanks

<BLOCKQUOTE>quote:</font><HR>Originally posted by MalibuDreamer:
Definitely sounds like you have vapor lock on the lines. Make sure all the fuel lines are away form heat sources, especially headers. Install one of those cheap clear filters, and you will probably see bubbles rising up.

<HR></BLOCKQUOTE>

I installed a clear fuel filter and sure enough lots of bubbles all the time. Does this confirm I have vapour lock? If so, would this cause hesitation/bog ar high RPMs? (3500+) What can I do to fix it?

Thanks.