Hey guys, I have an EF xr8 that wont keep running. I purchased it off a friend on the weekend that had lost interest in it and has been sitting for 18 months but was running fine when parked. there has been a lot of money spent on the motor including: full rebuild, gt40p heads, upgraded valve springs, crane Cams mild cam (not sure on specs) and crane cams roller rockers. The car is also running a stage 2 J3 chip and the car has done about 1000k's after all work was done.

Now once i got it home off the car trailer I sucked all stale fuel out of the fuel tank and replaced the fuel pump, in-line fuel filter, blew out all fuel lines, cleaned all spark plugs and dizzy cap contacts, checked all vacuum lines and intake connections.

When i crank it over it starts and runs for about 2 seconds and shuts off, initially i thought maybe the fuel pump isn't running continuously after startup and shutting off so i tested that with a test harness and multimeter but it all tests out good. So I checked the Fuel pump relay and ecu relay connections and even swapped relays with another spare I had, still no good. Next thought was the J3 chip, So I unplugged that and tested it, still no good.

I wasn't convinced so I played around with the J3 chip for hours and eventually it was running, but once i got it running it was missing and backfiring like crazy. I checked all spark plugs for spark and they were all okay. I couldn't figure out why it was missing so I went inside and had lunch. Once I came back outside after and hour I tried to start it and it wouldn't bloody start again!

So I played around with the J3 chip again and no matter what I do I cannot get it to run for longer than 2 seconds. I am stuck on where to go next because it seems very electrical like the power is getting cut to the injectors maybe? any help or thoughts from anyone would be awesome.

cheers

First, you should check the fuel pressure to ensure adequate delivery from the new pump, as low pressure may indicate a blockage. Next, inspect all electrical connections related to the injectors and ECU for corrosion or damage, and consider testing the stock ECU chip to rule out issues with the J3 chip. Finally, verify the ignition system's condition, including the coil and leads, as misfires and backfiring may stem from ignition problems.
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