The Stovebolt Site Forums The Shop Area Engine Shop GOT GAS, GOT SPARK, WON'T START!

I have checked my electric system and seem to have spark at my coil and plugs.
I have also checked, step by step, from the pump to the carb, to the fuel bowl, and down the throttle body. I pushed the pump piston and gas came out a hole, and the power jet assembly (I think) in the float bowl pushed down and sprang up. When I took off the throttle body there was gas going into the governor throat. So I think I am OK on getting gas to the engine. I sprayed some starter fluid in the carb and cranked her over. I got a couple of gasps and finally a small bang. That's all, but I could smell that something had caught! I can't get any more than this, though. What next?

sounds like it might be a "timing" issue..... check and make sure you haven't jumped time.....
Bring #1 up on TDC...and make sure the rotor is pointing at #1 on the dist cap.
Michael

I would check first the compression and second the timing. If you are getting gas, spark & air and it still doesn't run you either have low compression and/or it's not firing the plugs at the correct time. Check your compression with all of the spark plugs removed.

is it firing at the plugs themselves or the wire end//try a new set of plugs, they could be fuel fouled,brian

Here is what I would do: Sounds like the timing is way off. Twist the distributor way around and try the starting fluid again to see if you are getting closer. If not twist it around the other way. If one of them work noticeably better then I would reset my distributor. This is fire-extinguisher-at-hand time. Starting fluid is extremely flammable. An old engine out-of-tune could backfire through the crankcase too so be careful. Hope this helps.

I decided to check the timing, using my maintenance manual instructions. (I don't have tools for compresion testing.) I reset the manual advance, then hand cranked the engine until the pointer and flywheel mark lined up. But the rotor pointed to the #3 wire, not the #1. So I'm thinking the timing is way off or the spark plug wires are in the wrong distrib cap holes. Looking at the engine from the passenger side, my firing order is 1-5-3-6-2-4 (It's a 228 in a '53 GMC.) The order on the distrib cap, from the 12 o'clock position, was 6-1-2-3-4-5. I pulled the plugs and stuck them in 4-5-6-1-2-3. In other words I rotated all plugs clockwise 2 holes. (I hope that makes sense.) I turned the distrib housing until the points were opened and tightened things up.
With a fire extinguisher beside me, I cranked her over. I did get some firing, and some smoke blowing out the carb. A complete, accurate tune-up is a little beyond me, so I am thinking of having some old-timers at a local garage look it over. What do you think?

Okay, take the number 1 spark plug out of the hole. Take the dist cap off so you can see the rotor. Place your thumb over the empty spark plug hole. Have someone else turn the engine over while you watch where the rotor is pointing and note which way it is turning. When your thumb is blown away from the spark plug hole, make note of where the rotor was pointing. That should be where you need the #1 plug wire going. Then following the direction the rotor turns place the next plug wire so it goes to the #5, then #3, then #6, then #2, then the last hole in the distributor cap that's left will go to #4.

They shouldn't be on the cap in order 6-1-2-3-4-5 or 4-5-6-1-2-3. 1-5-3-6-2-4 is correct. Start with 1, then take the wire from 5, then the 3... I once wired it backwards... 1-4-2-6-3-5 on a 270 gmc. The engine still ran, but not very well! It seemed as though only 3 cylinders were firing. I was still able to get my truck up to freeway speeds. it was running really rough and I thought it needed a rebuild, but it was my dailey driver and I was going to drive it till it stopped! 2 weeks later I realized my mistake and got the old girl running right.

GMC 6s are tough and forgiving motors!

Same thing happened to me. Somehow I reversed two spark plug wires. Since I KNEW that I had the plugs in the correct firing order, I nearly tore my hair out trying to figure out what was wrong. I finally gave up and took it to a shop where they checked the firing order on the distributor switched two wires and fine tuned the timing. Now it purrs.

All right, guys ... I followed your good advice. After putting the plugs into the cap in proper order, I turned her over, and lo and behold, I got some decent firing. It almost sounded like it wanted to go! I got three or four fires, then a big "chunk", then three or four more fires and another "chunk". The
"chunk" would momentarily stop the turnover. I'm wondering if I have a bad plug, if timing is off, or ...

I think I can see the light at the end of the tunnel!

sounds like timing is off 180 degrees

I'm assuming the "chunk" is one cylinder firing too soon which would stop the rotation of the engine. It looks like you still have timing issues. These things are difficult to diagnose without seeing/hearing the engine. Taking it to the old timers you spoke of may be a good idea, especially if they'll let you watch & ask questions while they work on it.

Sounds like timing.
Have you ever seen this truck run?
Is you fuel new or old?
Is your exhaust open or clogged or bent?
I think some more diagnosis is ness. Pull out #1 plug, with a long thin screwdriver stuck in the hole use a wrench to turn over the engine untill you feel the piston move the screwdriver. When the piston moves the screwdriver to the top of the piston stroke (TDC or top dead center) look in the hole just above and to the rt. of the starter. This is the timing hole. Inside the hole you should see a ball emdeded into the flywheel or a line cut into the flywheel. If you don't see the ball or line, move the crankshaft with a wrench an inch in both directions untill you see the ball or line. With the ball or line in view remove the distributor cap and watch the rotor,with your wrench move the crankshaft untill the rotor begins to move and stop. Now make a mental note of where the ball or line is positioned in the hole. With your wrench move the crankshaft the oppisite direction and look for the rotor to move and then stop and look at the ball or line. Did the ball or line move more than 1/2 inch before the rotor turned? If it did you have timing gear or chain problems. If not put the plug back in and move the distributor as someone else spins it over and try to start the truck. If you rule out all other possibilities of spark, fuel,compression,and timing unbolt the exhaust and try to start it again. It might just be restricted. Good luck

Talk about obstructed exhaust, I got it to run a bit, and you should of seen the mice nests come shooting out!

I loosened the distrib clamp screw and turned the distrib back and forth to loosen it up. I rechecked the timing mark and rotor, set up the points, and replaced the plug wires in proper order (1-5-3-6-2-4). I pulled out the choke, pulled the throttle out quite a way, and turned her over. It popped once, it popped twice, I pushed the choke in, it fired and turned, fired more (with a few backfires), and then took off to the races at high rev! I throttled down and let her run for a couple of minutes. As I eased off the throttle more the engine lost power and quit. I have started a few more times the same way. I am concerned about the backfires, and why the engine "overrides" them when it gets going. Probably need to tune-up some more.

Sweet! Nothing better than hearing that engine fire up after it had been sleeping a while.
Check all of your vacuum lines for leaks. Pay speacial attention to the line that goes to the windshield wipers. If you have any other open holes in the intake plug them up. After you are sure you have no vacuum leaks, you could try to adjust the air/ fuel mixture of the carb.

You are 1/2 way there!

To expand upon what BigBadSwingDaddy said...

Have a look at your idler adjustment, too. It kind of sounds like it may be out of wack as well. Check the mixture first, though.