When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Did he install a new pump? Most of the time, when these problems, its the sender that is bad. If pressure is good, even at idle, until the engine warms up, and then it starts dropping to zero at idle, 9 times out of 10, its the sending unit.