Srinath

My 97 F150 truck 4.6 with 300K stalls abruptly. While moving even, and most of the times I can put it in neutral while still rolling, and start it, and shift back to drive and keep going.
Sometimes it may not start back up like today when coming to a light.

Then, If I get under the hood and wiggle the wires to the ECU and for good measure the battery and ground wires, it would usually start and run fine, till it happens again.
However today it felt like it needed some gas to fire back up so I hit the gas pedal and it started and revved up. And ran fine the 20 miles home.

I get home and with it idling, I cant get it to stall by wiggling the wires in the ECU or battery/ground cables.

Could someone point me in the right direction. Thanks for helping.

Jbrew

You answered your own question...great place to start.

Srinath

Really ? OK what would that answer be ?
It cant be fuel, because it will run 80 mph, however today it stalled going 5 mph.
Electric - fine, it didn't start without me giving it gas today, but otherwise it may start without me pumping the gas pedal.

paker

I would go over simples ones first. I would replace spark plugs and wires if they are old, check fuel pressure, and clean grounds.

Jbrew

Apologize Srinath,- I read this sentence as "can" vs "can't", -

"I get home and with it idling, I cant get it to stall by wiggling the wires in the ECU or battery/ground cables."

Check your MEGA fuses. The two large fuses by the battery against the firewall. A temp by-pass is the easy and fool prof way.

Jbrew

BTW- MEGA fuses are electrical. The reason for temp power loose is due to the solder ball at center. They crack vs blow causing intermittent failure at any given time. Which kills power to the fuel pump here and there. You never know when it's going to happen.

Srinath

Awesome Jbrew and paker. I will search tomorrow when I have some more daylight as I get home,

Srinath

The fuse block on the fire wall ahead of the glove box - both fuses were OK.
But the connector block under it - moving the wires to the right - the ECU side on that connector toward the fire wall - the truck keeps running. Moving it away from the firewall toward the front of the truck, even a tiny bit, the truck will stall, and when attempting to restart could act like no fuel, or no spark, or start like all is fine.
I think its in the plug itself, which is tight and on there good, but a break in that could be easily "not readily visible" from outside.
Is there a way to trouble shoot it with a tester or some other means, cos it looks like its still about 40 wires. I'm hoping to narrow it down. Maybe losing ground - or something shorting to ground (which will leave some nice burn marks - which I don't see on it).

Jbrew

Is it the big plug/connector right above the AC accumulator ? Old problem, but the harness can get close enough to create a magnetic disturbance. In turn, ignition havoc. Also the harness can come in contact with accumulator, chaffing the wires. The old fix was to repair any damaged wires and/or,- tie back the harness further away from the accumulator.

Srinath

Its that big square thing and yes above AC aluminum thing and under the big fuses inside the fuse box on the firewall right in front of the glove box.
Zip tie it up and toward the firewall is the solution ? I love it when my propensity to ziptie everything is the recommended solution.
I'll look for tore up insulation etc on the wires and if none, ziptie away.