I just put a brand new engine in my 1995 toyota 4runner, and it has been running great. The last couple of days however occasionally the engine will not start, and has been dieing on me while im driving. the engine turns over fine, and after several times of trying to start it sometimes it will start up agai nand sometimes it won't. It's leaving no problem code, and we checked the fuel pump and that seems to be perfectly fine. Could it be a relay going off and on, or do they just completly fail. Or could it be something else and what would that be?

Thanks

 

start by replacing the fuel filter.

make sure ground connections are good.

check make sure sessors are connected tight.

make sure plug wires are tight.