All Fuel lines are NOT created equal

["Eric" <ericp@xxxx>]

All high pressure fuel lines are NOT created equal. I have been 
battling a very unusual "part-throttle bucking problem". I have 
troubleshot and fixed many problems - all which were real problems on 
this car. But I have never been able to solve this 
underlying "bucking" problem.

Yesterday I removed my fuel injectors to make sure their spray 
pattern was fine, and their output equal. Both were OK, however I 
noticed this dripping problem on all injectors, and a slight delay on 
their engagement.

When I bought this car, one very noticable item was the brand new, 
high-pressure silicone (bright blue) fuel lines on all of the fuel 
distributor connections. The hoses are clearly embossed "250 PSI, 
high pressure fuel". I guess the guy before me felt it necessary to 
replace the lines, perhaps he had a problem. I never gave them a 
second thought, feeling very comfortable that the car had brand new 
high pressure fuel lines.

Well, I found out - BY ACCIDENT - these lines are very flexible. So 
flexible that you can squeeze one and actually make the fuel injector 
discharge a spray. THIS IS NOT A GOOD THING.

Anybody versed in hydraulics will tell you that soft, flexible lines 
will actually "dampen" that pressure "snap" that is essential to make 
these all mechanical fuel injectors work properly. So what happens...
You press the accelerator, air flows in, the air sensor plate moves 
down, the piston opens the fuel distributor, fuel rushes out to the 
injector...and the injector sprays...but only after it has slightly 
expanded the flexible fuel line and built up pressure to open the 
injector. The opposite happens when you let up from the accellerator. 
Your fuel lines can become a "Baffle" eliminating the 
hydraulic "snap" that is so important to the injectors.

The moral of the story - Don't use anything but the original semi-
rigid polyethylene lines (or whatever was factory). I have been 
battling this problem for months now. Who would have guessed it was 
this???

I hope sharing this story either helps someone fix, or prevents 
someone from making the mistake the owner before me had made.

Eric
Vin# 5557
Dunedin, FL
ericp@xxxx