GLOC336

Having problem with my 502 mag dying after being run for 20-30 minutes. Dies and just will crank with a little spitting and sputtering. Let it sit and cool off for a few hours it fires right back up just fine. Any ideas?

ziemer

iTrader: (1)

Sounds like vapor lock. These motors are notorious for vapor lock especially with the VST system, but will also do it on the cool fuel 502's.

Do a search on here and you'll find a bunch of topics.

liquidlounge

iTrader: (1)

exactly

buck35

I have never had the engine die while running around, mine would just not start after an extended shutdown, maybe but it could be electrical as well.

ALL_IN!

iTrader: (1)

Many of us have/had same problem on 502 MPI's. I went the Merc route and installed their add-on pump. It worked really well, and I never had the issue again (you can install this yourself easily). Others have run return lines back to tank, installed better pumps, etc. Many ways to skin a cat.

buck35

If you happen to venture out again and this happens check and see if you have spark, could be a coil about to take a crap.

GLOC336

Thanks for the info. This motor has the mechanical pump on the sea water pulley, is that the add on you are referring too? If so I replaced it this winter

92nsx

Mechanical pump feeds the electric fuel pump inside the VST located above# 7 cylinder. Unless your carb 502 mag.