1

Replaced the fuel pump on Dodge Intrepid 2001, 2.7L engine. Before dropping the fuel tank, drove it until about 1/8 full, so that it would be lighter. Installed the new fuel pump, strapped the tank back on, but when we went to fire it up, the engine wouldn't start.

After trying a number of things, we finally decided to pop off the vinyl quick-connect that connects to the steel fuel line to see if any fuel would pour out, but when we primped the pump we only saw a few drops, certainly not enough to start an engine. We added about 2.5 gallons to the tank, and it almost started. We added about 3.5 more gallons, and boom, it started right up.

Friend said the pump was vapor locked, but I thought that vapor locking had more to do with fuel boiling. Tried searching around the internet for an explanation, but didn't really find one. So, I ended up here. Anyone have any ideas why this happened? Thanks.

Pᴀᴜʟsᴛᴇʀ2
  • 165,084
  • 32
  • 259
  • 508
TLex
  • 75
  • 7

1 Answers1

3

Not vapor lock, but air lock. Different principle but the same effect. Air lock will only happen on a new install or if the tank is drained. The working parts of the pump are surrounded by air with maybe a little splash of gasoline, so the pump can not develop enough pressure to force the gasoline past the check valve at the pump.

The easy cure would have been to attach a hand-operated vacuum pump to the fuel line near the engine and pump until gasoline arrives. This would have eliminated the trapped air in the pump and would have given the pump enough liquid to create pressure.

MTA
  • 10,754
  • 1
  • 12
  • 38