sytyguy
Moderated User
We installed a brand new engine (one that I built) in Scott's '92, and it is running PIG rich at startup. It has a dead miss and pours fuel (accompanied by black smoke, fouling of plugs, etc....). Have tried varying fuel pressure to no avail. Here's what all we've changed/done:
- Set fuel pressure ranging from 48-32 psi
- Checked TPS, O2, IAT, CTS
- Tried 2 different chips (one modified/one stock)
- Checked for kinked line (nada)
- Checked for busted regulator (nada)
- Checked for open injectors (nada - fouls numerous plugs)
- Checked for vac leak (nada)
- ECM checked out good (Scantool reads, proper CEL flashing, etc...)
- Check for crossed wires (nada)
- Checked timing (close enough)
It blackened all the plugs, pours black smoke, and all sensors checked out fine.....which tells me that either it's getting abnormal pressure (not the case), the spark is too weak (it does stay running roughly with some pedal effort), or the ECM is commanding too much fuel (insert solution _____). All the grounds look good (esp. the ECM grounds), we're getting no codes (yet), and mechanically, the engine seems to be fine.
FWIW, it was a stock rebuild - stock cam, FM hypereutectic pistons, Comp lifters, stock valvetrain, etc.... Valvetrain appears to be adjusted properly (adjust half, rotate, adjust other half, etc....) and engine fires up convincingly.
Most of you know me, and I know a good deal about these trucks, but I'm hoping I overlooked something obvious. Any ideas? Hopefully I'll figure it out before anyone replies and makes me feel dumb... :wink:
Hood
- Set fuel pressure ranging from 48-32 psi
- Checked TPS, O2, IAT, CTS
- Tried 2 different chips (one modified/one stock)
- Checked for kinked line (nada)
- Checked for busted regulator (nada)
- Checked for open injectors (nada - fouls numerous plugs)
- Checked for vac leak (nada)
- ECM checked out good (Scantool reads, proper CEL flashing, etc...)
- Check for crossed wires (nada)
- Checked timing (close enough)
It blackened all the plugs, pours black smoke, and all sensors checked out fine.....which tells me that either it's getting abnormal pressure (not the case), the spark is too weak (it does stay running roughly with some pedal effort), or the ECM is commanding too much fuel (insert solution _____). All the grounds look good (esp. the ECM grounds), we're getting no codes (yet), and mechanically, the engine seems to be fine.
FWIW, it was a stock rebuild - stock cam, FM hypereutectic pistons, Comp lifters, stock valvetrain, etc.... Valvetrain appears to be adjusted properly (adjust half, rotate, adjust other half, etc....) and engine fires up convincingly.
Most of you know me, and I know a good deal about these trucks, but I'm hoping I overlooked something obvious. Any ideas? Hopefully I'll figure it out before anyone replies and makes me feel dumb... :wink:
Hood
