96 5.7 problems

[Big dreams]

hello everyone I’m new here and I’m still figuring out the site. I have a 1996 Chevy C3500 5.7L 4L80E
About a week ago the truck kept blowing the ecm 1 fuse some times it lasted a for mins before it blew others the min u put the key on it popped. Was told the fuel pump was going out I changed that and went to start it wouldn’t start the ignition coil went out on top of that changed that. Now I got her running and she idols fine revs fine but the min you go down the road and the sec you stop accelerating she kills
Some times she starts right back other you gotta try a couple times sounds like it’s camed when it don’t start right away but then again you can start it right back up in a min r two and she will idol fine and rev fine and it will stay idolling for as long as you want left her idol over 30 mins and nothing happens it only happens when trying to go down the road
I have gave it a tune up and the beginning of the year I just changed the crank sensor cause a so called mechanic friend said that was my problem when the ecm fuse was popping was also told as long as the truck was running it would relearn it self
Well I bought a scan tool to see about digging deeper seen the cam position retard was -13 when it should be between -2 to +2 well I turn the detribtor enough to get it at a + 1 and not it’s not throwing a p1345 code any more but it still killing going down the road some ppl telling the computer going out
I have seen tonight while messing with the truck the scan tool would lose communication sometimes
I do wanna upgrade to the 411 ecm I msg lextech just waiting on a response from the man
Any help would be greatly appreciate thanks in advance

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[Schurkey]

What is the fuel pressure? When was the last time it got a fresh fuel filter?

Look at the data stream. What is the short- and long-term fuel trim at idle (not idol)? What is the coolant temperature sensor showing when you FIRST TURN THE KEY ON? Should be the same as outside temperature. Do the O2 sensor voltages vary after the truck is in closed-loop operation?

Does the EGR valve work?

Find a GM service manual for the vehicle. What is EVERY power draw for the fuse that pops repeatedly? Have you checked the wire harness that is powered by that fuse?

I would un-plug every wire harness on the computer, inspect the pins on the computer and the harness plugs, and plug the harnesses back in firmly.

 

[Big dreams]

I don’t know what the fuel pressure is it got a fuel filter about a year ago

The fuse the only think I found that ran off it was the ecm and fuel pump

Egr valve I’m guessing it works I avg 11.5 mpg with the truck it it all ran fine till the ecm1 fuse blew

I’m waiting for it to go into closed loop as off 2 mins of idleing it still shows open loop

 

[Big dreams]

Live data stream

 

[Big dreams]

It’s showing it’s in closed loop now

 

[Big dreams]

This is 15 mins of idleing

 

[Big dreams]

Still not having any luck everything just seems fine even the plugs look good

The truck does good moving around the yard

It just seems like wants I get up to hwy speed it’s like I would just turn the key off

 

[Big dreams]

Changed the fuel pump again cause the new one I put in the sending unit wasn’t working swapped it out and now the gauge is working and now I can drive it longer before it acts up I got 3 miles out of it hit a bump it shut off I put it in neutral and the time I was on the shoulder it was back running so I turned around got half a mile it cut out put it make in neutral couple seconds it was back running fine and made it back home with it doing that only one more time fuel pressure with the key on motors off and with the pump running for that couple seconds is 61psi when the pump kicks off it drops to 52 with the motor running it sits around 52 rev up it goes to 60

I been checking wires and don’t see to fine any bad

 

[brian c lindsey]

maybe a bad ground