Issues with Conversion

[weazel]

I have been getting closer and closer to getting my 88 half ton on the road. But I've hit a road block.

I had originally had the engine running great with a harness I made.
Fast forward a few months, I attempted to build another harness, but with one that was in better shape. Got everything together, tried to fire it but kept popping fuses. Had such a headache with it, I went back to my harness I had it running with. Still no start. But it didn't pop any fuses.

More troubleshooting, got it to fire. But man it idles rough, lopes hard. Checked into with efi and saw max rail pressure. I've swapped out three fca but no change.

Any ideas where to go? The fca plug is at 3v off and let on. Idling I'm seeing 7.4v. I'm adding a pick of some of of the info efi gave me

 

[Harbin_22]

Not sure if it is related, but why is engine temp at 302°? Maybe something grounded or even unplugged that needs to be plugged in to complete the 5v circuit.

 

[weazel]

I noticed that too.
I've gone over and over the harness, but can't seem to find anything that's not plugged in.

 

[dirtydmax]

Had an issue like yours and ended up being a broken rail pressure sensor wire at the plug.

 

[weazel]

Did you attempt measuring voltage on your plug?

One side showed ground, and the other read 3v with the engine off key on. And 7.4v with it unplugged and idling.

A friend of mine is bringing a known good fca tomorrow to try, I'm really hoping that I just had bad fcas..

If he's not able to make it by, I'll try to ohm out the sensor wires. Thanks for the ideas so far to try

 

[dirtydmax]

Did you attempt measuring voltage on your plug?

One side showed ground, and the other read 3v with the engine off key on. And 7.4v with it unplugged and idling.

A friend of mine is bringing a known good fca tomorrow to try, I'm really hoping that I just had bad fcas..

If he's not able to make it by, I'll try to ohm out the sensor wires. Thanks for the ideas so far to try

Dont quote me but i think that 7.4 is wide open.think i recall mine being 1 ground,1 3.x and the 3rd a 7.x at idle with the broken wire.A broken wire at that plug caused my rail to max and ran like a bag $hit.got a new plug from Ben and all was good from there out.The wires seem to break really easy in that spot.

 

[jlawles2]

IIRC someone had an issue with their rail pressure being maxed out after HG. Turned out they had the FPR plug crossed with the low coolant plug (or another one).

 

[weazel]

Ok, I'm going to check into that for sure dirtydmax!

And I better double check the connectors, the rail pressure sensor and fca plugs look the same, now that you said that, I'm going to see if I can swap them, if it's a swapped plug that I messed up, I bet it's one of those two. The coolant plug is different than the fca plug. Now I did have that plastic protector deal off of the harness there for awhile as I was going to loom the harness there on top of the block to give me more room under the hood, and then decided to throw it back in there, so if I did swap plugs by accident, that's when I did it lol. Thanks for the thoughts guys, I'll get back on it after work today and see what I can come up with.

 

[weazel]

Curiosity got to me so I looked up some pictures of the two plug for the fca and rail pressure sensor. I don't think there's any way I could've swapped those two, as the fca is a two wire plug, and the rail sensor is a three wire..

So on to the next thought...

 

[rfletes79]

Ect 302............

I noticed that too.
I've gone over and over the harness, but can't seem to find anything that's not plugged in.

Not sure if you've already figured out the ECT issue yet but i've ran across the same issue with my car. Ended being a loose connection at the bell connector (engine side). I cant remember which color it was but if, while the ignition is on, you watch your data (on EFIlive) and start wiggling wires in the back of the
bell connector, believe its the lower of the 2, you should be able to narrow it down. If you peel back the wire loom at the ECT sensor you can identify the wire colors to look for at the bell connector. With the temp reading 302 it will idle high and prob be in some sort of limp mode.

Hopefully this helps.

 

[weazel]

http://s625.photobucket.com/user/we...AB-4168-919F-4FC35F77855C.mp4.html?sort=3&o=0

Here's how it idles. Does not respond to throttle input at all, but from what I've been told, at max rail pressure it won't let you do anything anyway.

 

[weazel]

A friend of mine and I did a lot of troubleshooting tonight.

Checked voltage values from the ECM to the fpr, tried running new cabling to eliminate a possible bad connection at the bale connector. Swapped out rail sensor. Attempted a few other things, but no change. The truck lopes hard at idle with the fpr/fca unplugged. As soon as you plug it back in, it will kill the engine.

To me, all the things we tried, leads me to believe something is wrong inside the ECM... Any thoughts about this assumption?

 

[RPM Motorsports]

How do you have the fuel plumbed? I tried to run two CP3's with a cp3 dedicated to each rail (temp), not tied together and using one rail for the sensor. Did the same as your describing until I tied the two rails together.

 

[weazel]

I've got 1/2" line from the tank to the feed tube on the rear/drivers side of the engine, and plumbing from there is all stock. I'm using 3/8" hose to return from the same point (smaller tube behind feed tube) back to the tank.

 

[RPM Motorsports]

I'm referring to the hard lines, stock form/location?

 

[weazel]

Yes, correct. Only difference from a stock truck versus this one is I'm using rubber lines to and from the tank..

 

[Bustedknuckles]

I helped diagnose a truck that acted about like you are describing, the FRP sensor iirc was plugged in with the plug upside down, i cant remember how it happened though, i think it was because the harness was off a newer truck.

 

[weazel]

That was one thing we looked into. We attempted to plug the fca plug in backwards, but it physically wouldn't go.

I went ahead and found another ECM to try. After disabling VATS, I was able to start the engine and it ran damn near perfect. So with the first harness, something was wrong with it and shorted out something in the previous ECM.

I'm going to clean up my messes, resolder these connections on this harness and continue on with the project. Thank all you guys for your opinions and advice with this issue, it ended up being a shorted ECM...