GN Spark Knock Help

[BadassBuick86]

ok, i have a 86 Grand National. it has a stock chip, flowmaster exhaust with no cats, and cold air intake. it Spark Knocks about 4 degrees because the fuel prssure is 3 pounds to low under boost. Ive replaced 2 regulators, 2 fuel filters, and 3 fuel pumps. and its still to low. The only thing i have left to change is the vacuum lines, they are showing a bit of dry rot and cracking. but any any help would be awesome. thanks all

 

[megaladon6]

IDK the GN specifically, but the older systems generally had a vac line that helped control fuel pressure. usually on the regulator.

 

[TexasT]

you may need something like this. http://www.racetronix.biz/itemdesc.asp? ... 06&eq=&Tp=

The stock wiring was marginal and now that it is over 20 years old it is even less able to get a full voltage and amperage to the pump.

 

[pontiacgp]

Have you replaced your timing gears?....if you have and used a metal gear instead of the fiber gear that will activate the spark knock..

 

[scot w.]

ok, i have a 86 Grand National. it has a stock chip, flowmaster exhaust with no cats, and cold air intake. it Spark Knocks about 4 degrees because the fuel prssure is 3 pounds to low under boost. Ive replaced 2 regulators, 2 fuel filters, and 3 fuel pumps. and its still to low. The only thing i have left to change is the vacuum lines, they are showing a bit of dry rot and cracking. but any any help would be awesome. thanks all

I would not go into boost untill you figure this out or you will be rebuilding the engine! Did you buy an adjustable fuel pressure regulator? If not, YOU NEED ONE! Then it needs to be set at 42-44 Lbs with the vacumm line OFF (and pluged up)..Then put the vacumm line back on..

A good website for tech answers is www.turbobuick.com


Scot W.