Why is my Plymouth Colt so hard to start when it's cold?

Short answer: If your Colt is hard to start or stalls only when cold and is fine once warm, the first thing to test is the coolant temperature sensor. It tells the computer the engine is cold so it adds extra fuel. A bad one makes a cold engine run lean. One 1989 owner also heard the main relay clicking on and off while it struggled, which is worth checking, since that relay powers the fuel injection.

Symptom: On cold mornings it cranks and cranks, maybe catches, then stalls unless you hold the gas down. Once it's warm it starts right up and runs fine for the rest of the day. The check engine light may come on.

What to check first

1. Have the coolant temperature sensor tested (resistance should change as the engine warms). A wrong cold reading is the top suspect.
2. Listen for the main relay. If it clicks on and off while cranking, have the relay and its solder joints checked.
3. Read stored trouble codes. These cars use older flash-code or scan-tool systems; a shop can read them.
4. Check for vacuum leaks at hoses and the intake, which hurt cold starts most.
5. Have fuel pressure checked to make sure it holds overnight.

Likely causes

1. Coolant temperature sensor. The first suggestion in the 1989 thread. A bad sensor makes the computer think a cold engine is warm.
2. Main (MPI) relay. The 1989 owner heard it clicking on and off during cold starts. This relay feeds the fuel injection.
3. Vacuum leak. Cracked hoses let in extra air, which matters most when the engine is cold.
4. Weak fuel pressure or a leaky injector. Worth testing if the sensor and relay check out.

What it usually costs

No owner posted prices in these threads. A coolant temperature sensor and a relay are cheap parts. Fuel system testing is mostly labor.

Is it safe to keep driving?

It's usually safe to drive once warm, but stalling at an intersection right after a cold start is dangerous. Let it warm up before pulling into traffic until it's fixed. Verify with a mechanic.

DIY or shop?

DIY for the sensor and relay. Testing the sensor with a meter and swapping a relay are simple. Fuel pressure testing needs a gauge, so many owners use a shop.

Recalls, bulletins and complaints in plain words

• Recalls: NHTSA lists no recall for starting or stalling on the Plymouth Colt in the model years we could check on 2026-10-27 (the recall lookup returned an error for 2 model-year queries). Check your VIN at nhtsa.gov/recalls. If your car is part of a recall, the dealer fixes it for free.
• Plain words: No recall we found matches this problem, so it's a normal repair, not a free recall fix. Still run your VIN, since other recalls may be open.
• NHTSA complaints: 4 keyword-matched complaints for Plymouth Colt 1985–1994 (of 129 unique complaints queried, NHTSA complaints API by model year, queried 2026-10-27; keywords: no start, no crank, click, starter, ignition switch, stall, dies, cold, hard start, relay, crank) (NHTSA returned no complaint data for 1 model-year queries). This counts complaints that mention these words. It is not a defect finding.

What owners report

• In Plymouth Colt - Trouble Starting Engine When Cold on Car Talk, a 1989 Colt with the 1.5L fuel-injected engine turned on its check engine light and clicked its main relay on and off when started cold. Holding the gas down kept it from stalling until it warmed up. A member's reply was to check the coolant temperature sensor.
• In Hard to start when colt on Car Talk, a 1992 Colt 1.5 needed 10 to 20 minutes of cranking and tries to start in the morning, then bogged down for a few minutes before running fine all day. Members asked for more detail and one asked about a turbo seal leak, but this car had no turbo. No final fix was posted.

Quick tip

Cold-only problems usually come down to whatever tells the computer it's cold. Test the coolant temp sensor before you replace anything expensive.

Vehicle focus: 1985–1994 Plymouth Colt (Mitsubishi Mirage twin), mainly the 1.5L.

Safety / mechanic note

Long cranking can overheat the starter. Crank 10 seconds at a time and rest it in between. Verify with a mechanic.