My DeLorean cranks but won't start after sitting. What should I check?

Short answer: If a DeLorean cranks but won't start after sitting, check for spark at the coil first. If it's weak or missing, clean and tighten the ballast resistor pack connections on the firewall. If it fires only when you swap the cold-start plugs, the problem is the thermo-time switch or its wiring. Don't leave plugs swapped: it floods fast, and fuel in the oil can damage the engine.

Symptom: The engine turns over normally but won't catch, even on starting fluid, often after months or a year parked.

What to check first

1. Check for a strong blue spark at the coil lead while someone cranks.
2. Clean and tighten the ballast resistor pack terminals on the firewall.
3. Make sure the cold start valve plug and the warm-up regulator plug (they look alike) are on the right parts.
4. Check the oil. If it's thin and overfull, fuel has gotten in; change it before cranking more.
5. If it starts only with the plugs swapped, test the thermo-time switch and its connector.

Likely causes

1. Ignition problem at the resistor pack or coil. The ballast resistor (a resistor pack on the firewall) feeds the coil. Its steel terminals rust and lose contact, killing the spark.
2. Flooded engine. Fuel soaking the plugs stops it firing. Swapped cold-start plugs can flood it fast.
3. Cold start valve or thermo-time switch circuit. The cold start valve adds extra fuel for a cold engine. The thermo-time switch decides when. Their plugs look alike and are easy to mix up.
4. Fuel system gummed up from sitting. After sitting, injectors, the pump, the filter and the fuel distributor can clog with old fuel.

What it usually costs

Owners in these threads didn't post prices.

Is it safe to keep driving?

A no-start isn't dangerous, but fuel in the oil can wreck the engine and starting fluid can backfire. Don't keep cranking a flooded engine.

DIY or shop?

Most of these checks are DIY with the workshop manual. Fuel distributor and injection work suits a DeLorean specialist.

Recalls, bulletins and complaints in plain words

• Recalls: NHTSA's recall and complaint lookups returned no data for this model in these years, which is normal for a car this old. Check your VIN at nhtsa.gov/recalls. If your car is part of a recall, the dealer fixes it for free.
• Plain words: The complaint count below shows how often owners reported problems that mention these words to NHTSA. A count is not proof of a defect.
• NHTSA complaints: 0 keyword-matched complaints for DeLorean DMC-12 1981–1983 (of 0 unique complaints queried, NHTSA complaints API by model year, queried 2026-10-30; keywords: start, fuel, stall) (NHTSA returned no data for 12 model-year queries). This counts complaints that mention these words. It is not a defect finding.

What owners report

• In Engine won't start on DMCTalk Forum, an owner restoring a DeLorean that sat a year had replaced fuel parts and found clogged injectors, but it still only cranked. Members said to clean and tighten the ballast resistor and coil connections, since corrosion there kills the spark, and to confirm a strong spark at the coil before chasing fuel. They also warned that repeated cranking can flood or even hydrolock the engine, and to check the oil for fuel.
• In Engine Cold Start Problem on DMCTalk Forum, a DeLorean that had sat would only start cold when the plug for the cold start valve was swapped with the other one. Members said that shows the cold start valve itself works and points to the thermo-time switch or its wiring and connector pins.

Quick tip

Spark first, then fuel. On these cars a rusty resistor terminal causes more no-starts than any expensive part.

Vehicle focus: DeLorean DMC-12, 1981-1983, PRV V6 with K-Jetronic fuel injection.

Safety / mechanic note

Flooding, fuel leaks and backfires are safety items. Verify with a mechanic.