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Beyond frustrated. 2000 blazer 240k

So I’m in the middle of rebuilding the 4l60e tranny but once I get it done there are still issues. Firstly there is a strong gasoline smell when it has been running. Avg of 7-10 mpg versus 15 previously. I have cold weather extreme hard starts. Starting fluid works most of the time but not always. New battery, plugs, wires and distributor cap. I am missing the cat and always have a check engine light as a result. I have changed the upper and lower intake gaskets. Incredible oil leak from the oil pan and possibly elsewhere. I have a complete engine gasket kit sitting at the post office awaiting pickup so hopefully the leaks will be coming. Does anyone have ideas? I do all my own work, but newer cars aren’t my forte, I mostly just get lucky and stumble across the fix but this has been two years in the making and I have stumped the locals.

You can do what you want but it sounds like you are wasting your time and money.

An air leak at the exhaust manifold gasket (or anywhere upstream of the first o2 sensor) could cause a fuel odor coming out the exhaust pipe. When that happens the computer thinks there’s too much o2 in the exhaust stream coming out of the engine, so it increases the amount of gasoline injected to try to burn it off. But that doesn’t work b/c the o2 is entering the exhaust stream after the combustion process, and so can’t be burned in the cylinder. The other common causes of too-rich operation is the thermostat has failed, or the engine coolant temp sensor has failed. Ignition problems of course can cause that too, but when that happens it is usually pretty obvious the engine is misfiring, rough idling, stalling, hesitation, etc.

You see pretty knowledgeable about Blazers there OP. Ray addressed a Blazer question in his newspaper column recently. About how to convert a 4wd Blazer to a 2wd, rear wheel drive in other words. Ray suggested the entire front axle had to be replaced. I was curious if the front axle could remain in place (therefore leaving the front suspension system intact) but just remove the front axle shafts from inside the front axle tube. I think I could do that on my 4wd truck, but do you think that’s possible on a Blazer?

Misfire on miscellaneous cylinders only ever one shown though. The cat was replaced by a flexible piece. I will check the sensor however the thermostat was probably replaced last year. Thanks for the thoughts.

Additionally this is a daily driver and I’d just like another year before we buy another vehicle.

Short and long term fuel trim readings are very helpful for figuring out rich/lean operation problems. Might pay to have a shop make those readings for you w/their scan tool, if yours doesn’t offer that function. Shouldn’t cost much for just that service.

For Pete’s sake George what does that have to do with the OP’s problem?


No . . . this truck has IFS

Leave well enough alone

Lost me. If you were asking me…sounds like a terrible idea. The amount of work you’d be doing, easier to find a two wheel model.

Holy Common Sense, Batman!

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Not worth the trouble

George was referring to a newspaper column that was probably reprinted from 30 years ago. K10 Blazers in the 1970’s and 80’s had solid front axles, nothing in common with S10 Blazers.

If you smell gasoline there must be a leak, have you tried to locate the leak? I doubt you will find gasoline leaking from the exhaust manifold. Look into repairing the misfire.

As for that fuel smell/leak, a few possibilities come to mind

The fuel pressure regulator, which is under the plastic plenum

One of the plastic fuel lines for the poppets has split, again under the plenum

One of the o-rings for the steel fuel feed and return lines has split, or the fittings are loose

If it’s one of the lines or poppets, that would explain the fuel smell AND the misfires

I have a full size 84 jimmy as well the statement still stands. It’s a big project.

Regarding your help that is extremely helpful. When changing the intake gaskets I didn’t change any o rings or gaskets. It’s possible they are worn and may have broken when I removed them to tear down the engine. I will replace them when I pick up the kit I ordered on Monday. Unfortunately success won’t be seen quickly. Still waiting on parts for the transmission. I will update as soon as I can get everything back together.

Can you clarify that, please?

So I’m presuming you replaced the upper and lower intake gaskets, but not the o-rings for the fuel lines?

That’s correct I removed the two lines on top as well as the distributor, plenum and intake to change the seals I did replace the plenum gasket because it came with the intake gaskets.

Thanks for the feedback, I think understand what db and Nevada mean. For the vintage Blazers with the solid front axles it might be possible, but not with the newer ones which use independent suspension on the front, not a solid axle tube from one side to the other. That makes sense. I was just curious about the techology is all, not intending to cause a commotion.

By gasoline smell do you mean as in leaking raw gasoline or do you mean an incredibly stench from rich running out the exhaust?

You state you have a complete engine gasket set waiting to be picked up at the post office. What are your intentions with that? Tearing apart a quarter million mile engine to replace gaskets is often a bad idea.

OIl pan gasket leaking? Maybe it’s not the pan at all but a leaking rear main. Maybe the rear main is leaking because the journal is horribly scored from miles or the main bearings are gone.
When opening up a high miles engine one quite often runs into a WTH next situation.

I can’t answer that. It smells strong. As for the kit. I highly doubt I will use all of it. My reasoning…autozone sells the oil pan gasket for 30$. The kit which includes the oil pan gasket cost me 50$. Intake gaskets cost me 30. Valve cover gaskets 19$. Lastly I don’t know that it’s not the rear main. I don’t know anything till I can look at it. But normally oil runs to the rear of a vehicle. Oil at the front suggests gasket. However I can’t say that for sure. Capillary action might pull oil along the seam.