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1997 Deville that is a smoke machine


tysonh80

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Hi guys,

I am a student at an automotive tech school. For a week or so I've been trying different tests on this 1997 deville trying to figure out why it smokes like a mofo. I'll list the things I've tried or tested at this point. I'm not really sure where else to check at this point. To me it seems to have several different problems.

Here were my initial observations with the car:

Misfire on #7 that caused a check engine light and was throwing a code for it.

With a camera inside #7 the top of the piston is much cleaner than the other pistons.

Compression test on #7 turned out normal.

Massive amounts of white smoke from exhaust after 2 minutes of engine running.

Black residue being ejected from tail pipes. Same residue that is located inside the intake. Same black residue drips down from where manifold meets the cat.

Exhaust smells like fuel 99% of the time, although today it smelled like oil.

Oil pressure is normal.

Coolant level normal and stable.

Temp. level normal.

Vacuum tested at 20 psi on intake.

Removed the injector on #7 put a camera inside. Both valves move when we bumped the engine.

Moved the injector from #7 and switched it with #3. Check engine light went off. Still smokes like a mofo.

The plugs on the car have a lot of black build up on them.

Sometimes when it smokes it doesn't smell like anything at all but the volume of smoke is incredible. Some how the build up in the intake is getting all the way to the exhaust and being ejected from the tail pipe. I would think we would get a code from the o2 sensor if a lot of unburned fuel is going passed it. My instructor told us to check something on the transmission but it turns out that this year doesn't have it. I've also read on this forum to check for a ruptured FPR. I haven't done this yet. I used a multi meter to test the ohms and voltage at each injector and they all were the basically the same. We also checked and confirmed the injector on #7 was firing. I initial thought because the top of the piston was clean, a valve was stuck open thus allowing the combustion mixture to escape. This turned out to be false. Letting it run or driving it doesn't stop the smoke. Sorry for the long post. Trying to get all the info in here. Thanks!

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Fpr diaphragm can rupture. I believe this allows fuel to be sucked thru vacuum hose. Will a totally failed Fpr suck lots of fuel into intake? Unplug Fpr vacuum hose and see what motor does.

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Sounds like the engine is running excessively rich on all cylinders. One or more injectors could be leaking. You'd need to lift the fuel rail and turn the key to ON and see if fuel is leaking from the injectors. Replace any that are leaking.

The fuel pressure regulator could be leaking as well - remove the vacuum line and start the engine. If there is fuel leaking out of the fuel pressure regulator nipple, the fuel pressure regulator is bad.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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You don't even have to start the engine to check the FPR, just turn the key on to pressureize the fuel system. Then check for leaks at the FPR. If there is gas, replace the FPR.

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