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View Full Version : is it Vapor lock, heat soak, etc?



whytry
10-01-2007, 09:27 AM
On my Camaro, procharged BBC, I am running the A1000 pump, stock sumped tank with fuel lines sizing per Aeromotive. This was not really an issue before but recently it has become one. I added the Flowmaster tailpipe kit and once the car sits for awhile @ a stoplight, traffic, etc I notice it stats running a little on the lean side according to my FAST AFR control. Once the car gets warmed up, is when I notice the problem. The car sounds like it has a miss when I notice this, and then logging the AFR showed me 17.1, when the car runs @ 14.0 normally.... The tailpipe kit does come close to the fuel lines at the back by the tank, where I ran the fuel lines to the framerail......

Z-man
10-02-2007, 09:21 PM
Maybe the exhaust is causing the fuel in the entire system to get too warm (assuming you're running a return line) - causing your fuel pressure to drop? That might cause it but I'm not sure. Do you have the pump controller?

whytry
10-03-2007, 08:30 AM
No pump controller, I do have a return line. I also noticed over the last couple of drives after shut off sometimes it sounds like the fuel is bubbling in the tank? or is that just the sound of the returned fuel going into the tank?

HILROD
10-03-2007, 12:42 PM
My fuel lines are kinda close to the exhaust. Well everything, is kinda close to every other thing in my car. I've had no issues with noise or vapor lock. I did notice when idling for a while, mostly at night (lights-heater), the voltage drop can cause fuel pressure drop and rough idle. Adjusting the idle up a tad would fix it for me.

whytry
10-03-2007, 01:39 PM
My problem is more after the long stop light when it's hot, once I start going is when the problem arises. Once I'm crusing along it seems fine again.

My427stang
10-06-2007, 07:00 AM
Whats the fuel pressure doing when this happens? You sure shouldnt be seeing vaporlock on a presssurized system, unlike us old carb guys :)

backtobasics
10-07-2007, 12:47 PM
I would look at some of the covers for fuel lines with the heat reflective coating. It should help reject some of the radiant heat from the exhaust. I would also consider some type of metal shield, or header wrap to minimize radiant heat.

gordonquixote
10-07-2007, 02:26 PM
There is a thread called 'Pressure drop' going right now with the same problem.

My car is acting the same way but it drives normal (but won't idle) , just no fuel pressure and the fuel filter is empty.

I just wrapped the hoses today to see if hot fuel was the problem and it acted the same way still - I'm running a mechanical pump but the symptoms sound the same.

whytry
10-08-2007, 07:59 AM
My fuel pressure does not drop @ idle, its rocks solid, even when I am noticing this problem. I did wrap the fuel lines with some of that heat reflective tape and it seemed to do the trick, but it was not that warm this weekend..... But it did not have the same symptoms as before..

gordonquixote
10-08-2007, 09:11 AM
I took a 1/2" ID hose, split it longwise and used it to wrap my fuel line with, this may help by providing an extra layer of insulation. The outside hose was very hot but the fuel hose inside was only warm.

Let me know what you find out.

whytry
10-10-2007, 08:58 AM
I took a 1/2" ID hose, split it longwise and used it to wrap my fuel line with, this may help by providing an extra layer of insulation. The outside hose was very hot but the fuel hose inside was only warm.

Let me know what you find out.

I wrapped it with the thermal tape, and then did this too, just in case. All seems to be fine now! The real test will be when it gets hot outside again....