Just picked up a 1997 Blazer LT for my son's first car. 160K miles. Drove into onto a flat bed for transport as it had a significant coolant leak. After traveling through a rain storm, when we went to unload it, No Start. Plenty of Crank. Fuel Pressure on the guage was in spec. Appeared to have spark. Changed out distributor and Rotor. Started, but ran poor. Black Smoke, SES light on. Ran long enough to trace the coolant leak. Intake manifold Lower gasket. Completed thr repair and also changed out plugs and wires in that process. Thanks for the excellent info on the gasket replace. 1st time working on this vehicle and all went quite smooth. Started up and initially ran much better. Leak problem appears to be solved, but still set SES light. Scanned initially as P0300, then when cleared several times and re-set. Keeps coming back as P0305. The history on this vehicle is that it sat for about a year, so I am suspicious the problem is with fuel. Are there any effective cleaning procedures, etc. I will attempt to drain the remaining fuel, but I fear the damage may already be done in the injectors. Another piece of info os that when I replaced the lower gasket, I noticed a good deal of carbon soot in the intake manifold. I cleaned out as much as possible, but maybe this is a clue to a bigger problem?? I've searched and read through as many posts as I could find, which have given me great infomration, just trying to start down the path that might be the most likely candidate. I also picked up a coil but have not yet replaced it, thinking that I would probably have more than one cylinder misfiring if I had a coil issue.

 

did you do a compression test? try swapping plugs and wires around to see if you get the mis fire from cylinder 5 to move.

 

Thanks. Haven't checked compression yet, but will do that. Tried swapping wires and plugs. Initially ran a bit better code was actually gone for a few minutes. Maybe didn't get warm enough to run the code at first. MIL returned with a P0305. Cleared the code again. Returned this time with a P0304. Cleared again. MIL returned with a P0300. Running very poor. Very rich. Black carbon from the exhaust. NOt sure whether this is a fuel problem now or something much bigger. Big unknown in this is that the vehicle has sat for quite some time, so it may have some real issues. I'm going to put the new coil on as good measure, then get to work on the fuel draining and try some injector cleaning. Will end up checking the compression all around as well. Interesting that when I pulled the #1 plug to swap it with #5, it had black soot developing as well.

 

clean the EGR valve and port

 

Took off the EGR valve. Some carbon deposits, but not too bad. Cleaned out as best I could. Valve move easily. No friction. Swapped out the coil as well. No difference in operation. Have not been successful in getting the tank drained as of yet. Thought that would be easy, but no such luck

 

do you blow out the EGR valve with compressed air? it has to be compressed air... also take the distributor cap off and turn the rotor left and right to see how much play you have. it is very common very the dist. gear to wear out on these trucks...

 

I wasn't real sure how to clean it, so I didn't use compressed air. Just cleaned out as much carbon as I could with a brush and Q-tips. I'll tajke it back off and do a better job. When I replaced the distributor cap, I notice there was some play, which I thought was a bit odd. I would estimate about 3 to 4 degrees of play (Does the gear wear on the shaft? Reason I ask is that when I had the distributor out for the intake manifold gasket, I inspected the gear and I didn't notice anything unusual on the teeth themselves). I'll try and get a good measurement. Also, just an update I did take it out for a short ride. After it cools down for a while, It seems to run better. It lit up a P0300 code, which I cleared and continued to drive. I drove a couple of miles only (< 25 mph) and although it did not illuminate the MIL again, there were 2 codes pending. a P0172 and the P0300. I'll start researching the P0172 as maybe yet another clue.