Very Poor Running After Plug/Coil Pac Install

[aracerx]

WELL, just changed plugs and coil pacs to discover 04 GT3 is now running very poorly. reinstalled parts with same results! changed oil at same time along with removing the front cover for debris removal. NO CODES SHOWING EITHER. Checked fuel pressure as when spraying carb cleaner into throttle valve, engine perked up and sounded good, albeit for a few seconds. Looks as if fuel pressure is low, possible 10lbs? any thoughts always appreciated-thanks

ran fine before-hah

[clord]

Hi aracerx.... You may well have low fuel pressure and it may just be a coincidence to your plug/coil pak work. In my own '04 GT3 I had similar poor running in the minutes before my fuel pump quit. The original pumps in '04 used a variety of hoses on the in-tank pump. Remember that our cars are based on the C4 unibody for it's additional stiffness (as were the Cups cars). The C4 body requires a saddle shaped fuel tank and so the single pump has to have "jet pumps" to lift fuel out of the two low points in the tank (the pump is in a well right below the dome cover). The resulting plumbing is confusing. The pump has one short piece of hose that takes a tight turn in about two inches. It has been known to split at the tight turn. The result is that fuel leaks there reducing line pressure and eventually over working the pump to failure. Have a look.

Let us know what you find.

[aracerx]

Hi aracerx.... You may well have low fuel pressure and it may just be a coincidence to your plug/coil pak work. In my own '04 GT3 I had similar poor running in the minutes before my fuel pump quit. The original pumps in '04 used a variety of hoses on the in-tank pump. Remember that our cars are based on the C4 unibody for it's additional stiffness (as were the Cups cars). The C4 body requires a saddle shaped fuel tank and so the single pump has to have "jet pumps" to lift fuel out of the two low points in the tank (the pump is in a well right below the dome cover). The resulting plumbing is confusing. The pump has one short piece of hose that takes a tight turn in about two inches. It has been known to split at the tight turn. The result is that fuel leaks there reducing line pressure and eventually over working the pump to failure. Have a look.

Let us know what you find.

thanks for help.........too much of a coincidence though.......I broke something.......trying to locate fuel pressue regulator as maybe vac hose came off or broken

[JMcD]

Better late than never. I had the same issue at 5K miles, 11/07. The dealer said it was caused by a faulty fuel pressure regulator in my 2004 GT3 (8/003). It blew the fuel pump hoses in the tank.

Who knows..., but that is what they wrote on the work order.

Jack