1992 Chevy Lumina - sometimes it starts, sometimes it don't, flip a coin

Saturday Evening: vehicle lurching or bucking while driving down the road

Sunday afternoon: similar, card dies altogether, but cranks strong

- changed air filter, fuel filter, inserted concentrated Heet and concentrated STP fuel injector cleaner. No change. Vehicle engine light comes on when attempting to start, and stays on, but no codes are stored. Checked fuse and relay associated w/fuel pump (swapped 2 relays, identical part #'s), no change.

Monday morning: car starts fine

Monday evening: drove it short distances, problem appears to have disappeared.

Tuesday, Wednesday, Thursday, etc: same results

Saturday afternoon: drove the car for about 10 miles, started to lurch/ buck, then dies, refuses to start. Maybe it isn't entirely accurate to describe it as lurching/bucking, but rather a refusal by the car to accelerate or maintain acceleration/constant speed.

Sunday morning: car starts fine. While accelerating (when parked), car cuts out about 4 times, but resumes, eventually dies, but restarts. Later, car won't start at all. Still later, car starts. When cranking (when it wouldn't start) I'd either hear the fuel pump come on or shut off (in any event I heard it). When the car was cutting out (but didn't die altogether), I can smell something like rotten eggs (of course I've smelled it before, but this smell was *different* or just not as strong).

- what to do? Does hearing the fuel pump mean everything is kosher inside the tank (integral pump and sending unit located in tank)? Or could that filter be clogged and be causing the problem? Can a fuel pump filter (inside the tank) be blown out w/compressed air?

Could these problems be related to a clogged cat or other exhaust components? Would cutting out the cat and installing a strait/test pipe tell that tale (I can always save the cat and have it spotted back on)? There is a small hole on the side of the body of the muffler, that drips a fair amount of water, even dirty water perhaps, and, though I won't swear to it, w/a faint smell of gasoline.

I'm told fuel pumps just die usually, and aren't intermittent. There's a wire/connector near the driver side strut tower, is that the place where you apply 12 volts to determine if fuel pump will come on? Even if it does, that doesn't tell me if it's intermittent, does it?

Could the problem be an electrical connection (having to do w/the fuel pump) that's intermittent? If you've been following these posts, I was the guy w/the leaky power steering pressure hose (no it wasn't the return line, sorry). Could that fluid have gotten somewhere it shouldn't and fouled something up? To me it doesn't sound like it though.

Of course the *Ford* owners are gloating right now. Everything that ain't a Chevy falls into the *Ford* category.

What are the other possibilities? I doubt it has anything to do with ignition components, because when cranking the car (when it won't start), and again it cranks strong, I don't smell any gasoline.

Incidentally, can you drop the fuel tank when the car is up on ramps, or is there insufficient clearance?

Thanks in advance...

Reply to
Chris
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All kinds of things could be wrong. First pull a plug and verify you have good spark. Then check the pressure at the fuel rail.

If you don't have spark, does the ECU know the engine is turning?

Without actually checking fuel, air, spark, and timing, you really don't have much information.

They could, but there are plenty of easier ways to find that problem, including just unbolting the manifold. If the engine turns over easily, though, that's an unlikely one.

Fuel pumps are often intermittent.

You need to actually measure fuel pressure before you go poking around with the fuel system. Otherwise you will just be wasting your time.

The ECU will not turn on the injectors if it doesn't see the distributor turning. And it will shut the fuel pressure off after a few seconds if the engine doesn't start up by itself. So the fuel odor is no longer a useful diagnostic like it was in the carb days.

--scott

Reply to
Scott Dorsey

My (understanding is, that smell (SO2) occurs when the catalytic converter is overwhelmed with unburned fuel. IOW, flooded.

And, just something to consider, we had a car with somewhat similar behavior (an 80's Buick, IIRC), that was due to a bad air-flow sensor (MAF).

G
Reply to
George

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