89 7.4l Tbi Dying.

[hhiibel]

here's the timeline of events.

 

i messed up putting on a 4wire O2 and had 5volt constant to ecu.

Mechanic went to OEM 1wire O2 replaced all sensors and ecu.

truck ran fine.

Then it started dying seconds after startup.

Mechanic had a moment of genuis and traced it to a loose ecu connector.

Truck ran fine.

then truck had intemittent freeway stumble that eventually led to dying during idle at start up.

Mechanic replaced fuel pump. Said pressure was reading low.

3hours of run time later the problem is back.

Start it up. As it goes to low idle it nearly dies then idles some more and gets to full heat sink and dies. Subsequent restarts are hard and the idle time before dying shortens.

 

So maybe i got a bad pump or maybe there's something causing the pump to go out.

what could cause a pump to go out in about 3hours?

[Cadha13]

Have you changed the fuel filter? Sounds like fuel starvation.

One other question, how can you put a four wire O2 sensor onto a one wire harness?