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shotout1234

OK one of the most wanted items in America is the cover for the firewall mounted chassis load center on a 387 Peterbilt. So like numerous other owners mine didn't have a cover on it and trashed the fuse box. This truck has been an electrical nightmare. It's a 03 with a CM 870 and yes everything else was so bright and shiny and new on it when I bought it at auction I thought I would take a chance on the freedom line 12 speed transmission. What a mistake but I'll get to that later. so someone gave me a fresh fuse box with the wiring harness as I could not see any other way to start to get the electrical gremlins out of this thing. how much of my problems are tied to the transmission as a matter of interpretation I think. But here's my point, I'm not certain what application that the fuse box and wiring harness that I used was. from a caterpillar application. How bad of a mistake that I make? I have one harness lead that I don't know where that goes to and I don't have one for the power washers. so I have no power to the lift pump. If you give her ether she will start of course I don't do it for about a second but it's not an ignition problem it's a fuel problem. Or maybe it's the stinking transmission not sending the proper communication to the motor. I don't know, someone please just start to steer me in the right direction. today I run a direct line to the lift pump see if it's any good. In the interest of getting it running high was going to pump air into the fuel tanks to push the fuel past the lift pump. but then I'm up against the fuel stop solenoid. as you can see I'm no mechanic but I am determined. it has defeated Peterbilt, it has defeated three local garages but I will win eventually with some help from someone here. Before this damn thing breaks me. is probably TMI but I wanted to paint a picture of how lost I am as to which way to proceed. I suppose the Insite program would give me a lot of information as to where I'm lacking?

Rawze

Your post was all over the place like a bowl of spaghetti.

Are you saying that with ether.. it fires off and stays running on its own after that?. - Are able to drive away? .. or it just fires off a bit and dies again?. -= you were not very clear on that.

As far as the electric lift pump goes... there is a relay buried in the engine wiring harness that controls it via the ecm. I have seen many trucks where the relay was missing, or had gone bad. Also, sometimes the lift pump itself is bad.

Any ways ... to troubleshoot fuel supply + engine no start issues ...

Monitor the fuel pressure in Insite while cranking. If it is not above a set pressure reading, the engine computer will not even try to fire the cylinders.

here is a similar thread...
http://rawze.com/forums/showthread.php?t...6#pid11426

RocketScott

Slapping an unknown fuse box and wiring harness into your truck is almost guaranteed to be a headache. Wiring requires attention to detail

You need to get everything connected correctly before trying to troubleshoot. All the little electrons need to go where they are supposed to and stay away from where they're not. Ignoring that will keep it from running at best. At worst you'll let the magic smoke out of components

Baco74

Those transmissions work on 24V,and they have voltage doubler mounted on the top off trany.If they go bad your not going to start.

Rawze

(05-20-2023 )Baco74 Wrote: Those transmissions work on 24V,and they have voltage doubler mounted on the top off trany.If they go bad your not going to start.

The feedom-line tranny manual can be found publicly here ...
ref https://assets.wellertruck.com/reference...-guide.pdf