I have been runing the stock fuel pump for the last year on my 402 stoker ls1. Car puts down almost 490 to the rear tires. I knew the fuel pump was living on borroed time and it has finally let go. I am wanting to go with the walbro 340 intake pump and just wondered if a retune would be in order if I did this? It doesn;t seem like it would be required but i just wanted to ask

 

Also is the 340 Walbro the biggest single pump you can run or is there a larger version??

 

Your question has a couple of catches and what-ifs. At 490 RWHP, there is a good chance that the stock fuel pump was dropping pressure. IF this is the case, then a retune will be needed. Also, IF the stock pump was gradually going bad, your trims could be a little out of whack compared to your original tune. If this was the case, then you would be fine long term, but might run poorly on initial install of the new pump.

 

When I had it tuned the first time. I asked about the fuel pressure dropping and he said there were no issues with it during the dyno and street tuning phases