Weird probelm

[caminokid]

I have a problem that makes no sense. Its a 250 L6 auto. It has spark. All the ignition stuff is new. New fuel pump. New starter. Dump gas into the carb and it wont fire. I took off the carb...and the manifold had gas in it. I pulled the plugs...and they are dry. I dont know what the problem is. It makes no sense. Anybody got any ideas? I have never seen this before. I have never had a problem with a L6 running.

[OlChev67]

that is a weird problem. I know there is somebody out there that can give you better thoughts, but heres some of mine.
-Are the plugs good?
-Maybe something is grounding when trying to crank the engine
-How long has it been since its been running?
-Is it HEI or points distributor?
if the plugs are dry, and you are dumping gas in, maybe its not getting to the cylinders? stuck valves, plugged manifold.

Check all simple things before you tear into something.
Hope I helped

[caminokid]

Originally Posted by OlChev67

that is a weird problem. I know there is somebody out there that can give you better thoughts, but heres some of mine.
-Are the plugs good?
-Maybe something is grounding when trying to crank the engine
-How long has it been since its been running?
-Is it HEI or points distributor?
if the plugs are dry, and you are dumping gas in, maybe its not getting to the cylinders? stuck valves, plugged manifold.

Check all simple things before you tear into something.
Hope I helped

I dont know how long its been since it ran last. All new ignition parts...cap rotor plugs wires coil starter HEI...But the plugs are dry when I pulled them out to check them.

Maybe stuck valves...next thing I am checking.

[Luvlegs]

I know you said it has spark but are you sure there is 12v feeding the coil? - not the original wiring (drops voltage to 9v I think) that would keep you from actually getting the 12v needed to really make it spark. Plugs gapped at .045?

After re-reading (doh) I see the plugs are dry indicating the fuel is not getting to them.... hmmmm maybe try a small shot of ether... hmmmm..... can you turn it over by hand? Geesch - thought I had an idea but now, I'm flailing.... well, this'll keep ya at the top if nothing else....

[Palf70Step]

I am thinking maybe a broke timing chain not allowing the vales to open.

Pull the valve cover and see if your valves are even moving.

[cdowns]

Originally Posted by Palf70Step

I am thinking maybe a broke timing chain not allowing the vales to open.

Pull the valve cover and see if your valves are even moving.

no timing chain 6cyl
how did you check spark? with a spark plug out touching the block while engine turns over?
ignition stuff new?? is it installed correvctly? if points did you set dwell with a meter?

[caminokid]

Originally Posted by cdowns

no timing chain 6cyl
how did you check spark? with a spark plug out touching the block while engine turns over?

Yeah that what I did. The valves are opening. Took the valve cover off...watched all of them move.

[Luvlegs]

Here's a weird possibility - is the engine painted? the manifold? Any chance the guy that put it together masked off the ports, painted it and then put it together and left the tape on? When bringing to TDC, are you getting a puff out of the plug hole?

[GMCBubba]

luvlegs, it sounds like you're speaking from personal experience!

i'm sure i'd do something dumb like that

[Luvlegs]

A few years ago, I ALMOST did it with a cylinder head - I was trying to figure out if the holes were going to line up with the new gasket and then DOH! I took the tape off... ya never know when it comes to POs.... Like my buddy that had his dad look at a hot 396 Chevelle - PO couldn't get it to run at all - sold it "as is" out of frustration - CHEAP! - they towed it about a mile away - my buddy was upset about his dad spending his money on the car but he thought dad could get it going for him. They pulled over his dad said "pop the hood" - he hooked up a wire and a vaccum line and it fired right up - he drove it home smiling like he'd won the lottery!

[beautimus]

first off i wouldn't be to concerned that the plugs are dry.
the plugs come in from the side of the head, you could have a bunch of gasoline standing on the piston top and it still might be dry. (just my opinion) with that said, lets walk through this. if i mess this up somebody chime in and correct me.

lets assume that this thing was running a while ago, has been sitting up and your trying to get this puppy to run again. is that correct?

now you pull it out of the weeds and do the tune up stuff. but it just spins and spins. you check for spark, because you know that you just put points, plugs, wires,and maybe a condensor, cap and rotor. (if i'm on the right track let us know).
okay first off, is the spark blue and strong or orange and weak?
(Orange could mean that the coil is weak or something else is not right in the ignition system)
okay, if its strong and blue, your good lets move on from there.
okay next is gas, is the gas your using fresh gas or does it smell old?
you have pretty much taken the fuel system out of the equation by pourin gas down the carb. so if its getting some gas and good spark,it should try to start. thats all i can think of ,
and if its stuff you already know, please don't be offended. sometimes it helps me think a problem through if i walk it through like this. i'm hopping it will help you too.
good luck to you, Tony

[68gmsee]

Originally Posted by beautimus

first off i wouldn't be to concerned that the plugs are dry.
the plugs come in from the side of the head, you could have a bunch of gasoline standing on the piston top and it still might be dry. (just my opinion) with that said, lets walk through this. if i mess this up somebody chime in and correct me.

That's correct... Just because they're dry doesn't mean there's no fuel getting to the pistons..

One thing I would try: Have someone crank it and place your hand or hands over the carb to cover it completely. You should feel some suction.

Check your timing again. Makes sure the #1 piston is on the compression stroke and at TDC.

Then check to make sure your pulley lines up with the mark for TDC and insure your rotor is pointing to the #1 piston.

With ignition key set to on, move your distributor until you get a spark from the #1 plug wire to the ground. That's a good starting point.

[hyarbour]

Could the distributor be 180 out; or worse yet, the cam?

[72BLUZ]

The Cam Or Timing Is What I'm Thinking. But If Its Electronic Ignition It Could Be In The Distributor

[caminokid]

Yeah I have good strong spark. The head is a integral head...meaning the head and manifold is molded together. Cant take the Intake off the head....somebodys good idea in the 70's. All the valves are moving. Timing is right on the money. The distributor is rebuilt. The coil is new. Fuel pump is new. Starter is new. Using fresh gas. I unhooked the fuel line...for awhile there I wasnt getting any gas at all. The gauge said I had a half a tank. After I got gas to come up...the gas smelled good. No varnish smell.

Tony...no Offense taken. The run through helps. It just proves I havent missed anything you mentioned. My other thought is maybe a critter has gotten into the manifold and made a nest deep inside it. But I cant take the intake off the see what has happened.

I wish I had all the L6 parts I had back in the 80's. I would have another head and intake to toss on there.

I know this sound crazy...I am going to part out the truck for my 69. I just would like to see that 6 run before I rip the truck apart. I know someone may need a 6 for their truck someday. I might be the one that needs it for all I know. If I was to keep the truck I would drop a 350 in it real quick. I have one sitting.

[jhow66]

Take each plug out and squirt some oil in each hole. Turn engine over some then reinstall plugs. Cylinder walls my be dry.

[Boog]

Do a compression test on it. It'll tell ya if ya need to go any further.

[68gmsee]

Originally Posted by Boog

Do a compression test on it. It'll tell ya if ya need to go any further.

Originally Posted by 68gmsee

One thing I would try: Have someone crank it and place your hand or hands over the carb to cover it completely. You should feel some suction.

The hands over the carb is a quick check to see if rings are working. But, a compression test would tell a lot. Maybe previous person didn't adjust the lifters correctly. Too tight, and there won't be any compression or suction.

[Blue_71]

i have to agree-- do a compression test. you could have stuck rings from sitting, or bent valves, or valves too tight (always open)

[caminokid]

I know its getting suction to the carb. When it turns over...you can see the choke move. Meaning I watch it get sucked down. I am going to get a compression tester tomorrow.

[Luvlegs]

Soooo... any updates?

[caminokid]

Started parting it out. Wasnt going to mess with it anymore. The 69 is getting fixed.

[Luvlegs]

PM sent

[caminokid]

You guys are going to love this. I was tearing the truck apart. I seen it had a catalytic converter on it. I knew those are worth money at the scrap yard. So Pulled it off. The damn thing was plugged! I put a battery back on the frame rail and hooked it up. I squirted some gas in the carb...and Bam! It started! Everyone here including me didnt think about that. Lesson learned.

[herb101]

I've had the exact same problem on an import many years ago. I was under the impression this was an older truck and never dreamed to expect a cat being part of the picture. Sorry I assumed that - I could have spoken up about the cat stalling the engine.

Herb