Fuel in intake but not getting into cylinders

[Newfie98]

Here's a weird one for you guys.

Just finished putting in a used 355 SBC in my C10 last fall just before the snow started to fly. Made a few trips around the block in it and it ran ok but needed some adjustments that I thought I would sort out this summer.

Fast forward to last month and I put a brand new 600 CFM Holley carb on it and the truck started and ran better than ever. Never did get a chance to drive it with the new carb on it as I was finishing up a few other odds and ends with it when it started to act up. I shut it off one evening and went to start it the next morning and all of sudden it wouldn't start which was a bit of a surprise as it used to fire up first flick of the key with the new carb on it.

After digging into I have discovered that I have good spark and compression, but no gas in the cylinders. I can see gas in the carb through the glass sight plugs and if I pull the carb the intake is wet with fuel (not overflowing but wet enough that it should start). However, when I pull some of the spark plugs they are dry.

I am not sure how to explain this. I have done a few things in trying to diagnose this:

Pulled the valve cover and cranked it over to ensure the timing chain wasn't broken or that something else wasn't blocking the valves from opening.

Swapped an older Holley 650CFM carb on it that I had lying around just to make sure the new carb wasn't the issue (you never know!)and I get the same trouble.

Pulled the distributor and reset the timing by putting #1 on TDC just to make sure the timing wasn't the issue.

Changed the coil as I read on another forum someone having a similar problem and this fixed it but still no luck.

So at this point the truck will crank and turn over fine but won't try to start at all. Fuel is getting to the carb and intake but not getting pulled into the cylinders.

Anyone out there have any thoughts on why this could be?

Thanks,

Cameron

 

[Snoots]

Broken timing chain?
Check to see if the distributor is turning while you crank it.

 

[Matt69olds]

Pull the plugs, if they are wet with fuel they won’t fire. If the intake had fuel in it, I would check and see if you have the float level set too high, a leaking fuel needle/seat, or some other reason the engine is flooded.

Disable the ignition, pull all the plugs. Crank the engine over several times to blow out the excess fuel. You may have luck cleaning the plugs, probably best to replace them.

 

[Newfie98]

Distributor turns fine when cranking and I have good spark.

The float level is set correctly in the carb, fuel level is right at the bottom of the sight glass.

My issue seems to be a lack of fuel as the plugs (which are brand new) are dry when I pull them.

 

[Snoots]

Mechanical or electric fuel pump? Either way, disconnect the fuel line at the carb and crank it.
I'm of the belief that fuel at the bottom of the sight glass is too low.

 

[mtnmankev]

If I had the problem of fuel not making it into the cylinders on my truck engine, I would expect to find either a bird or packrat nest built in there blocking the flow.
My home is ground zero for weird things to happen.

 

[Newfie98]

Mechanical pump, plenty of fuel spraying out when I unhook the lines at the carb. The carb bowl was full above the sight glass when I first installed it out of the box but I adjusted the floats so that the fuel level was good at the bottom of the sight glass.

If I take fuel from a bottle and pour it directly into the carb it will still just crank and make no attempt to start, and the plugs remain dry.

I doubt there is any nest in my intake as it ran good one day and went to start the next morning and I've been having the same trouble ever since.

 

[Radiohead]

Still has compression? If I missed that my apologies.

 

[Galane]

Broken timing chain?
Check to see if the distributor is turning while you crank it.

It helps if you actually read the OP before you reply.

"Pulled the valve cover and cranked it over to ensure the timing chain wasn't broken or that something else wasn't blocking the valves from opening."

 

[Galane]

Pull the plugs, if they are wet with fuel they won’t fire. If the intake had fuel in it, I would check and see if you have the float level set too high, a leaking fuel needle/seat, or some other reason the engine is flooded.

Disable the ignition, pull all the plugs. Crank the engine over several times to blow out the excess fuel. You may have luck cleaning the plugs, probably best to replace them.

Oh good grief. Why don't people READ every word? He said "However, when I pull some of the spark plugs they are dry."

 

[Galane]

A used engine you say? Small block Chevy engines are notorious for getting their lifters stuck where they won't rotate. What soon follows is wiping out the camshaft. They'll keep running until there's not enough valve lift happening.

Had a 1978 Chevy van that ran well but also ran coolant out the exhaust. The prior owner had ignored the leaking heater and ran it dry enough to crack both heads. While replacing the heads with a set of rebuilds I decided I should pull a lifter to check and see how they looked. Hooo-boy. Extremely worn. Pulled another and it was worse. Almost every lifter had its base gouged out. No idea how it ran so smoothly. So the engine got a 327 performance regrind cam (the only SBC cam in stock anywhere locally) and a new set of lifters. Really woke that van up, and helped it drain the 40+ gallon tank extra fast.

 

[Snoots]

It helps if you actually read the OP before you reply.

"Pulled the valve cover and cranked it over to ensure the timing chain wasn't broken or that something else wasn't blocking the valves from opening."

Not my pay grade.

 

[Radiohead]

It helps if you actually read the OP before you reply.

"Pulled the valve cover and cranked it over to ensure the timing chain wasn't broken or that something else wasn't blocking the valves from opening."

When half the country runs on delusion, you expect reading comprehension? Lol

 

[Matt69olds]

Oh good grief. Why don't people READ every word? He said "However, when I pull some of the spark plugs they are dry."

How careless of me, I failed to specify the dry plugs are probably fine.

The OP mentioned when he pulled the plugs, some were dry. That suggests some were wet with fuel. Those won’t fire.

Now, everyone happy?

 

[Newfie98]

Whoa I didn't mean to start anything here haha.

After talking to another older fella who is very knowledgeable with these engines he suggested that the timing was off. He thinks the reason I am not seeing gas on the plugs is that it is being sucked out through the exhaust valve before it can fire.

I have tried re-timing the engine by removing the valve cover and setting the rotor towards number one and vacuum advance towards number six. I hooked up my timing light while cranking the engine over and aligned the mark on my balancer with the timing tab. This hasn't fixed my issue but if I continue to turn the distributor clockwise towards the firewall (way past where the timing should be) I start to get some life, the engine attempts to start and almost wants to go.

I know you will all be saying to check the mark on your balancer and timing tab but I have used these same marks to time this engine before with no trouble in the past.

I am going to double check my plug wires tomorrow to make sure they are in the correct order (should be as I didn't mess with it before I started having issues) but I feel I am getting closer to source of my problems.