Why does my Cadillac Fleetwood blow black smoke or smell like gas, then die?

Short answer: Black smoke or a strong gas smell from the tailpipe means the engine is getting too much fuel. On the 1993–1996 Fleetwood with throttle-body injection, a member pointed to a torn fuel pressure regulator diaphragm, which lets raw gas into the engine. A leaking injector or weak spark can do the same. If it then cranks but won't start, listen for the fuel pump.

Symptom: After sitting, it sputtered, blew black smoke and died, and now it catches but won't run. Or you smell raw gas at the tailpipe and the engine cuts out while driving.

What to check first

1. Turn the key to on and listen for the fuel pump to run for a couple of seconds.
2. Have fuel pressure tested, and check the regulator vacuum hose for gas, which means a torn diaphragm.
3. Look at the spark plugs. Black, wet plugs mean it's running rich.
4. Watch the injectors in the throttle body with the engine cranking for dripping.
5. Find a shop or car club that knows these older Cadillacs.

Likely causes

1. Ruptured fuel pressure regulator diaphragm. The regulator keeps fuel pressure steady. When its diaphragm tears, raw gas gets pulled into the engine, which floods it. A member pointed to it on a 1993 car.
2. Fuel injection problem. On these throttle-body injected engines, a stuck or leaking injector can dump too much fuel.
3. Ignition problem. A bad plug or other spark problem leaves unburned fuel, which you smell at the tailpipe.
4. Fuel pump, relay or fuse. For a crank-but-won't-start, members said to listen for the pump first.

What it usually costs

No owner posted prices in these threads.

Is it safe to keep driving?

A strong gas smell is a fire risk, and a car that cuts out while driving is a crash risk. Park it until it's checked. Verify with a mechanic.

DIY or shop?

Mostly shop. Plug checks are DIY, but fuel pressure and injector testing are best done by a shop.

Recalls, bulletins and complaints in plain words

• Related recalls: NHTSA lists this recall touching this area of the Cadillac Fleetwood: 94V210000 (1994 model year, fuel tank strap fasteners). Check your VIN at nhtsa.gov/recalls. If your car is part of this recall, the dealer fixes it for free.
• Plain words: On some 1994 cars, the fasteners for the fuel tank straps weren't tightened, so the tank could sag and drag. That isn't the cause of black smoke or a gas smell at the tailpipe, but if you smell gas under the car, get it checked right away. Still run your VIN. Verify with a mechanic.
• NHTSA complaints: 9 keyword-matched complaints for Cadillac Fleetwood 1993–1996 (of 85 unique complaints queried, NHTSA complaints API by model year, queried 2026-10-28; keywords: smoke, gas smell, fuel smell, stall, won't start, cut out, dies, rough, regulator, injector). This counts complaints that mention these words. It is not a defect finding.

What owners report

• In 1995 Cadillac Fleetwood black smoke and now won't start on Car Talk, an 87,000-mile 1995 Fleetwood sat for three weeks, then sputtered, blew black smoke from both tailpipes and died. Now it cranks and catches but won't run, with no codes. A new fuel pressure regulator didn't help. Members said to listen for the fuel pump at key-on, then check the injection system, and noted black smoke can mean too much fuel.
• In 1993 Cadillac Fleetwood - Gas smell from exhaust on Car Talk, a 1993 Fleetwood smelled strongly of gas from the exhaust and cut out while driving, and the shop couldn't find the cause. Members noted it has the Chevy 350 V8 with throttle-body fuel injection and pointed to the injection system or ignition. One said to check whether the fuel pressure regulator diaphragm in the throttle body had ruptured, and others suggested asking a local car club for a shop that knows these cars.

Quick tip

Pull the small vacuum hose off the fuel pressure regulator. If gas is in it, you've found your problem.

Vehicle focus: 1993–1996 Cadillac Fleetwood (rear-wheel drive, US).

Safety / mechanic note

Gas leaks are a fire risk. Don't smoke or work near sparks, and relieve fuel pressure before opening any line. Verify with a mechanic.