1990 engine flooding
08-07-2014, 02:32 PM
#1
4th Gear
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1990 engine flooding
when cold, engine starts up and idles/ drives perfectly. After idling for some time and warming up, the engine begins to flood itself and black smoke pours out of the exhaust until eventually the engine dies. Any ideas as to why this happens?
I should also mention that if you begin driving right after starting the engine, the car will run perfectly until it is shut off again.
I should also mention that if you begin driving right after starting the engine, the car will run perfectly until it is shut off again.
08-07-2014, 03:52 PM
#2
when cold, engine starts up and idles/ drives perfectly. After idling for some time and warming up, the engine begins to flood itself and black smoke pours out of the exhaust until eventually the engine dies. Any ideas as to why this happens?
I should also mention that if you begin driving right after starting the engine, the car will run perfectly until it is shut off again.
I should also mention that if you begin driving right after starting the engine, the car will run perfectly until it is shut off again.
you have an obvious fuel system failure, either...
the blown Fuel pressure regulator diaphragm, or damaged FPR plunger
or
a stuck, damaged fuel injector or several
or
a shorted fuel injection harness.
Whats happening and why...
the reg for ex, test this by pulling the vac hose off the reg after its "flooded" itself.
see if there is wet gas in the vac hose. IF there IS, the reg diaphragm is definitely the problem and MUST be replaced immediately.
IF the vac hose is dry, and the engine floods, move on to fuel injectors.
This is a batch-fired inj system. That means that 1 electrical circuit fire all 4 injectors in that bank. Short out 1 injector and all 4 short out. When they short they always short out to the OPEN position. Open fuel injectors under 40 psi of pressure will FILL a cylinder with liquid in a second. IF that crank shaft continues to turn, you WILL cause a piston to attempt to compress the liquid and it WILL BREAK that piston, or bent the rod like a pretzel, or tweak the crank. THIS CAN BE FATAL !
I'm leaning toward an electrical short since you say its intermittent and comes at different times. Get it to idle, then start wiggling the injection harness around until you get a result.
I would NOT drive this car until you find the source of the problem. Like I said, a flooded engine that TRIES to rotate WILL break or bend something...and it can be disastrous. This is known as "hydro'ing" the engine. Trying to compress fluids is not possible in this universe.
believe me, I know. Go ahead and ask me how I know.........
Seriously, if its flooding to the point of blowing lots of black smoke and trying to stall the engine, and if the starter acts like its having a hard time cranking the engine to restart, you are within fractions of a mm of blowing the motor.
EFI engines do not flood. If they DO, something is seriously wrong.
EVEN IF....it were not so bad as to hydro the motor, you are still washing all the lubricating oil off the cyl walls and rings, bearings and other wear parts, which will accelerate the wear by 1000 times. Your killing it by continuing to drive it in this condition !
Do another quick, easy test....
pull the dip stick and sniff the oil. IF you can smell ANY gasoline odor, call the tow truck ! IF the dipstick shows TOO MUCH oil in the crankcase, tow it. That's NOT oil....its raw gas in the oil and that's NOT good !
It is entirely possible that you have some other problem that's unrelated to the fuel system. BUT, knowing the severe consequences of a fuel system failure like I have described, its well worth your time to investigate and KNOW what you're dealing with. Fix it today and it's only a $75 FPR diaphragm. Wait till tomorrow and it could be a total rebuild.
Keep us posted. These engines have this FPR or injector problem and its not uncommon.
Good luck !
08-07-2014, 07:36 PM
#3
Race Director
GREAT reply...I am curiously waiting for the poster to reply.
Fuel in you oil is a grenade waiting to go off....especially if it is excessive. I have had some fuel injected engines that have come in my shop with oil so high on the dip stick...that when I drained it....there must have been a gallon of fuel in the crankcase.
DUB
Fuel in you oil is a grenade waiting to go off....especially if it is excessive. I have had some fuel injected engines that have come in my shop with oil so high on the dip stick...that when I drained it....there must have been a gallon of fuel in the crankcase.
DUB
08-08-2014, 08:10 AM
#4
GREAT reply...I am curiously waiting for the poster to reply.
Fuel in you oil is a grenade waiting to go off....especially if it is excessive. I have had some fuel injected engines that have come in my shop with oil so high on the dip stick...that when I drained it....there must have been a gallon of fuel in the crankcase.
DUB
Fuel in you oil is a grenade waiting to go off....especially if it is excessive. I have had some fuel injected engines that have come in my shop with oil so high on the dip stick...that when I drained it....there must have been a gallon of fuel in the crankcase.
DUB
I had an experience that literally scared the **** outta me and caused me to run out of the garage screaming !
Engine was flooding and barely able to crank over....I had not put 2 + 2 together yet....this was also early in my C4 ownership back around 1990....
long story, short......
it finally burped, backfired and started. Ran like crap gurgling and chugging. Sitting half in the driver seat to keep a foot on the gas pedal and looking behind for smoke color for a clue and I see LIQUID spraying out of the tail pipes....1st thought....Friggin great ! Coolant...damn. It's head gasket time,.
That's about when I realize the overwhelming odor of GASOLINE ! Then I realize that it ain;t coolant.....its RAW GAS blowing out the pipes! All this is happening about the same time...
lots of "shock and aw " hitting me at once.....
I bailed. Ran out of the garage trying to find the cell ph while running. Had every intention of calling the fire dept before I burnt the house down.
After a few minutes and nothing started burning, I returned...cautiously walking up to, then IN the garage with fumes so thick it was hard to inhale.
Investigation revealed the #1 injector had shorted to ground thru the inj coil body and was ARCING from the inj to the intake manifold....nice big blue arc with each rt bank inj cycle. This in turn shorted the whole rt bank...causing them ALL to be hung WFO.
Gasoline dripped from my FLOODED exhaust system for hours. Had to roll the car out of the garage and let the wind take the fumes that lasted the rest of the day.
Pulled the dipstick and it was FULL to the top. Must have been at least 1.5 GAL of extra liquid in the crank case. When drained, the fluid gushed out like water under pressure...thin and LOTS of it.
Took 3 oil changes to get most of the gas smell out of there. I kept the 4th and ran it for a week before changing it again.
Got NO idea what kept that thing from blowing to pieces....with the rt bank pumping raw gas into the front Y pipe like a garden hose was stuffed in there and the left bank adding red hot exhaust,.
normally fire and fuel do not mix........Somehow I avoided hydro'ing that engine. Somehow...just dumb luck. It should have blown apart and bent rods and broken any of the 4 pistons in the rt bank. Or all....
I walked away from THAT near disaster with a new found respect for high pressure fuel injection. Nothing will send a chill down your spine faster than the thought of sitting in a car that's about to explode and burn !
08-08-2014, 02:30 PM
#5
Race Director
Check the CTS (Coolant Temperature Sensor) on the front of the intake manifold. If it is disconnected, a broken wire or there is a bad connection the ECM will think the coolant is -40° and it will richen the mixture.
Another possibility (as mentioned earlier) is that the FPR (Fuel Pressure Regulator) diaphragm has ruptured and it dumping raw fuel into the plenum through the vacuum line. To check for this, take the vacuum line off the FPR and turn on the ignition (don't start the engine). Check for fuel coming out of the FPR. The fuel pump only runs for 2 seconds at ignition on, so either have someone else turn on the ignition or put a rag or something under the FPR to see if it gets wet with fuel. When my FPR diaphragm ruptured I had a fire in my engine compartment, so this is something you should take care of right away.
Another possibility (as mentioned earlier) is that the FPR (Fuel Pressure Regulator) diaphragm has ruptured and it dumping raw fuel into the plenum through the vacuum line. To check for this, take the vacuum line off the FPR and turn on the ignition (don't start the engine). Check for fuel coming out of the FPR. The fuel pump only runs for 2 seconds at ignition on, so either have someone else turn on the ignition or put a rag or something under the FPR to see if it gets wet with fuel. When my FPR diaphragm ruptured I had a fire in my engine compartment, so this is something you should take care of right away.
08-08-2014, 05:48 PM
#6
Race Director
leesvet,
I am HONESTLY GLAD to read that you escaped a MAJOR TRAGEDY in your above description of events on 'that day'.
I also...have a TOTAL RESPECT for pressurized fuel systems....and high energy ignition systems...and many others.
DUB
I am HONESTLY GLAD to read that you escaped a MAJOR TRAGEDY in your above description of events on 'that day'.
I also...have a TOTAL RESPECT for pressurized fuel systems....and high energy ignition systems...and many others.
DUB
08-11-2014, 10:31 AM
#8
Drifting
Dub,
I had an experience that literally scared the **** outta me and caused me to run out of the garage screaming !
Engine was flooding and barely able to crank over....I had not put 2 + 2 together yet....this was also early in my C4 ownership back around 1990....
long story, short......
it finally burped, backfired and started. Ran like crap gurgling and chugging. Sitting half in the driver seat to keep a foot on the gas pedal and looking behind for smoke color for a clue and I see LIQUID spraying out of the tail pipes....1st thought....Friggin great ! Coolant...damn. It's head gasket time,.
That's about when I realize the overwhelming odor of GASOLINE ! Then I realize that it ain;t coolant.....its RAW GAS blowing out the pipes! All this is happening about the same time...
lots of "shock and aw " hitting me at once.....
I bailed. Ran out of the garage trying to find the cell ph while running. Had every intention of calling the fire dept before I burnt the house down.
After a few minutes and nothing started burning, I returned...cautiously walking up to, then IN the garage with fumes so thick it was hard to inhale.
Investigation revealed the #1 injector had shorted to ground thru the inj coil body and was ARCING from the inj to the intake manifold....nice big blue arc with each rt bank inj cycle. This in turn shorted the whole rt bank...causing them ALL to be hung WFO.
Gasoline dripped from my FLOODED exhaust system for hours. Had to roll the car out of the garage and let the wind take the fumes that lasted the rest of the day.
Pulled the dipstick and it was FULL to the top. Must have been at least 1.5 GAL of extra liquid in the crank case. When drained, the fluid gushed out like water under pressure...thin and LOTS of it.
Took 3 oil changes to get most of the gas smell out of there. I kept the 4th and ran it for a week before changing it again.
Got NO idea what kept that thing from blowing to pieces....with the rt bank pumping raw gas into the front Y pipe like a garden hose was stuffed in there and the left bank adding red hot exhaust,.
normally fire and fuel do not mix........
Somehow I avoided hydro'ing that engine. Somehow...just dumb luck. It should have blown apart and bent rods and broken any of the 4 pistons in the rt bank. Or all....
I walked away from THAT near disaster with a new found respect for high pressure fuel injection. Nothing will send a chill down your spine faster than the thought of sitting in a car that's about to explode and burn !
I had an experience that literally scared the **** outta me and caused me to run out of the garage screaming !
Engine was flooding and barely able to crank over....I had not put 2 + 2 together yet....this was also early in my C4 ownership back around 1990....
long story, short......
it finally burped, backfired and started. Ran like crap gurgling and chugging. Sitting half in the driver seat to keep a foot on the gas pedal and looking behind for smoke color for a clue and I see LIQUID spraying out of the tail pipes....1st thought....Friggin great ! Coolant...damn. It's head gasket time,.
That's about when I realize the overwhelming odor of GASOLINE ! Then I realize that it ain;t coolant.....its RAW GAS blowing out the pipes! All this is happening about the same time...
lots of "shock and aw " hitting me at once.....
I bailed. Ran out of the garage trying to find the cell ph while running. Had every intention of calling the fire dept before I burnt the house down.
After a few minutes and nothing started burning, I returned...cautiously walking up to, then IN the garage with fumes so thick it was hard to inhale.
Investigation revealed the #1 injector had shorted to ground thru the inj coil body and was ARCING from the inj to the intake manifold....nice big blue arc with each rt bank inj cycle. This in turn shorted the whole rt bank...causing them ALL to be hung WFO.
Gasoline dripped from my FLOODED exhaust system for hours. Had to roll the car out of the garage and let the wind take the fumes that lasted the rest of the day.
Pulled the dipstick and it was FULL to the top. Must have been at least 1.5 GAL of extra liquid in the crank case. When drained, the fluid gushed out like water under pressure...thin and LOTS of it.
Took 3 oil changes to get most of the gas smell out of there. I kept the 4th and ran it for a week before changing it again.
Got NO idea what kept that thing from blowing to pieces....with the rt bank pumping raw gas into the front Y pipe like a garden hose was stuffed in there and the left bank adding red hot exhaust,.
normally fire and fuel do not mix........Somehow I avoided hydro'ing that engine. Somehow...just dumb luck. It should have blown apart and bent rods and broken any of the 4 pistons in the rt bank. Or all....
I walked away from THAT near disaster with a new found respect for high pressure fuel injection. Nothing will send a chill down your spine faster than the thought of sitting in a car that's about to explode and burn !
Crazy s***. Just goes to show you, anything's possible. You must have GM's rare "explosive/sadistic" personality version Corvette, that obviously likes you enough to keep you alive, but apparently enjoys terrifying the living s*** outta you. Especially considering that fiberglass is like wood to a fire.
I seem to remember a long time ago up here on the forum....maybe 8 years ago or so, one of the members said he woke up one morning to a KABOOM in his house that rocked the walls. It's sounded funnier than s*** until I realized it was his Corvette. I seem to remember him talking about leaving a cigarette near the engine or something of the like(can't remember how he explained the igniting factor) and he posted a pic of his garage door blown open, piles of smoking black crap in every direction and in the very center, a roasted black chassis with what resembled four wheels on each corner. I remember thinking....I know these vettes definitely give you the most bang for the buck, especially with the opposite sex, but damn, that's ridiculous.
Last edited by MaSTeRofDZaSTeR; 08-11-2014 at 10:34 AM.