Engine - Idle Surge, No-Start or Stall
84mitsubishi01SUBJECT:
FBC ENGINE IDLE/SURGE CONDITION - (DSV)
NO. STB-84-14-006
DATE February 1984
1984 2.0L Cordia/Tredia MODEL 1984 California Montero
INTRODUCTION
Symptoms of road-load surge, no-start or no-idle below 1500 rpm on 1984 Feedback Carburetor (FBC) equipped 2.0L Cordia/Tredia models or California Montero models may be traceable to an open circuit in the Deceleration Solenoid Valve (DSV) on the carburetor.
FIGURE 1 - LOCATION OF DSV AND ESV:
FIGURE 2 - LOCATION OF JSV:
LOCATION OF THE DSV
The DSV is a normally-closed valve that is held open by electrical current. It is screwed into the carburetor below the dashpot (Figure 1) and may be identified by its blue and red leads. There are two other identical looking valves on the carburetor - one is the Enrichment Solenoid (ESV) (Figure 1), and the other is the Jet Solenoid Valve (JSV) (Figure 2). These two valves differ internally from the DSV, and the three are not interchangeable.
TROUBLESHOOTING DIAGNOSIS
When an open circuit occurs in the DSV, the valve closes, cutting off the idle fuel supply. The result of this is:
1. Engine won't idle below about 1500 rpm.
2. The engine may not start.
3. A surge may be noted at road load. If any of these symptoms appear, check the DSV for an open circuit.
FIGURE 3 - TEST FOR DSV OPEN CIRCUIT:
TEST PROCEDURE
1. Measure the resistance across terminal pins 4 and 7 on the carburetor connector (Figure 3). The resistance should be = 50 ohms if the DSV coil is OK. If the DSV fails this test, it is bad and must be replaced. Even if it passes, it may have an intermittent open circuit, and the only way to test for this condition is to replace the DSV with a new one and observe whether the surge, no-start, or no-idle condition disappears.
FIGURE 4 - REPLACEMENT DSVS:
REPLACEMENT
1. Unscrew the DSV from the carburetor and disconnect the red and blue leads from the connector. Observe whether the replaced DSV has a small white plastic ring near one of its terminals. This will help determine which of two replacement DSVs is needed. See Figure 4.
2. Check the vehicle build date on the vehicle certification label, If before 9/83, it has an "early" carburetor (no plastic ring on the DSV leads) and the correct replacement DSV is MD608699. If after 9/83, it has a "later" carburetor (white plastic ring on the DSV leads) and the correct replacement DSV is MD612005. See the table at right, and refer to Parts Bulletin MSPP008N84.
3. Install the correct DSV.
WARRANTY CONSIDERATION
Normal warranty procedures apply.