Blazer Forum - Chevy Blazer Forums - Engine swap; Now it cranks but won't start

ok, this might get long...

I bought a '98 Chevy blazer LT, loaded up leather and the goodies. it is a vin W. I bought the blazer knowing it needed an engine, It started up and ran it just knocked pretty bad. but it was running, before the swap. anyway, I tore the old engine out and then realized there was a vin 'x' or 'w', my blazer is a W and unfortunately the donor engine was an X, also unfortunately was that it came from a 2wd truck not a 4x4 like my blazer. so we swapped the oil pan and oil pump. the junk yard assured, then reassured me it would work even though I realize the x has less HP??? there seems to be some confusion on this. but I don't want to turn this thread into a dissection of x's and w's. :)

after we swapped the needed pieces we wrestled it back into place, bolted everything up, etc. a couple things I noticed, one; both engines have two temp sensors, one right on the top front of the engine in the thermo housing and another on on the drivers side of the block, about the exhaust manifold and below the valve cover gasket. the sensor on the side of the block has a single black wire about 12 inches long coming off of it that has an electrical connector that mounts to a bracket on top of the engine. the second sensor in the thermo housing has a yellow and black wire feeding it. here was my issue, the one in front plugged in fine but the harness does not seem to support the one on the drivers side! there is not connector coming off the harness to plug into the sensor! so I guess i'll start it up and see if the gauge works, or so I was trying to do :/

also, there were about three black wires bugged together right over the trans bell-housing. I don't know why there like that but I figured if it ran before just leave good enough alone. these are not the wires that ground the the rear of the heads.

on the donor engines distributor, on the bottom portion (not the cap) where the screw threads in was cracked when I got it, so that screw is not very secure.

so here I am now; I have it all together, save the temp sensor, but the engine cranks and cranks but will not start! the battery is weak but I had it on a charger some today and then was jump starting it. the voltmeter on the dash was reading under 14 but when cranking it didn't seem to be draining the battery. it was still hooked up with jumper cables the whole time. I really don't think it was lack of juice in the battery, it seemed to be cranking fine. is there something that wouldn't allow it to start if the battery was totally shot, even if it was cranking over with the jumper's connected?

I was getting fuel, I depressed the valve stem looking thing on the fuel lines and it came squirting out. also, I removed the spark plugs to check for spark and there seemed to be plenty of fuel on them. except for two maybe, the number 1 and 6 cylinders, those have a different plug wire boot on them and seemed a little dryer than the rest. I wasn't able to get number 3 because it was blocked by the steering shaft. as far as checking for spark goes I don't have a lot of xp, they were sparking but it didn't seem really blue or orange, more just white??? some of the plugs seemed more blue but would that depend on how well it was grounded on the engine?

when cranking for an extended period (5-10 seconds) it almost gave a muffled backfires? kind of in sync with the engine crank. I don't know if I have just a couple cylinders trying to fire off and the others are dead? I really have no idea.

I recently had a no start issue with my little nissan sentra, and was at my whits end after checking everything I could. I read online those cars are known to have flooding issues if you start them up for only a short period of time. something about not letting it reach operating temperature allows gas to drip in the engine, effectively flooding it and not allowing it to start. which was my case with the car. we started it several time loading/unloading it from the car dolly. I read to remove the fuel pump fuse and crank the car a few times then continue cranking it while slipping the fuse in and out till it started, and by golly it worked!! I removed the fuse on the blazer and cranked a few times then replaced it but no luck... not sure what to do. could the cap not being tightly clamped on the distributor (because the cracked screw socket noted earlier) cause this issue? its not like its jumping all around or anything, the screw just isn't biting well.

one last tid bit; the crank sensor connector had a chip out of it so we replaced it with the one off the old engine. we threaded out the bolt and bolted it on the donor engine, simple as that. or is there more to swapping the sensor than that? my first engine swap was the nissan discussed above and it went a lot smoother than this! beginners luck I guess..