Riviera V6-3.8L SC VIN 1 (1995)
PROM - Programmable Read Only Memory: All Technical Service Bulletins
Fuel System - 20-30 Second Rough Idle after Hot Restart
File in Section: 6E - Engine Fuel & Emission
Bulletin No.: 67-63-01
Date: May, 1996
Subject:
Rough Idle after Hot Restart (Replace Fuel Pressure Regulator and Mem-CAL)
Models:
1995 Buick Riviera
with 3800 Supercharged Engine (VIN 1 - RPO L67)
Condition
Some owners may comment about a 20-30 second rough idle condition after a hot re-start. This condition may be most noticeable after the vehicle has
been driven until fully warmed up, parked for about 1/2 hour, and them restarted.
Cause
The combination of a high RVP (Reid Vapor Pressure) fuel blend along with high fuel rail temperatures and low fuel rail pressure creates a condition
where the fuel in the rail and/or injectors begins to vaporize. The vaporization causes bubbles to form and creates a rough idle condition until the air is
purged from the fuel system (usually 20 - 30 seconds).
Important:
High altitude also makes the condition worse.
Correction
1.
Check for and repair any Diagnostic Trouble Codes that may be present.
2.
Install a 1996 design fuel pressure regulator which will increase the fuel system pressure from 39 psi to 52 psi (measured with vacuum hose
disconnected).
3.
Install the revised MEM-CAL.
Important:
Both the fuel pressure regulator and the revised MEM-CAL must be installed during the same repair visit.
Parts Information
Parts are currently available from GMSPO.
Warranty Information
Labor
Operation
Description
Labor Time
Use published
J6364
MEM-CAL - Replace
labor operation
time.
Use published
J5560
Regulator, Fuel
labor operation
Pressure - Replace
time.
