Initial symptoms: Running rough, hesitation.
Having previously had a clogged/sticking Needle in the carb, I decided to rebuild with a kit from Holley.
After much cursing and gnashing of teeth, adjusting and readjusting, it started and ran. Hesitation seems worse, especially when accelerating from a full stop.
Drove it about 25 minutes. Then it was very hard to start and ultimately died.
Fuel filter was full of sludge. Replaced filter and pump.
Crank, no start.
Then I noticed the distributor has come loose.
I reset the timing.
Crank, no start.
It is getting spark.
The carb bowl is at the right level, so gas is getting to the carb.
When I crank, the throttle plates are wet.

What should I check next?

 

I would drop the tank that sludge came from and see about cleaning it or replacing it.
How old is the fuel in this tank?


Why did the dist. come lose?

If you have spark and have fresh fuel in the carb could it be flooded?
How do the plugs look? Are they wet from fuel? How old are they and what is the gap?
You sure you have the timing set right being the dist. came lose.
Try turning it a little in each direction and see if it will start.
Dave ----

 

Pretty new. This is my daily driver so fuel turnover is pretty good.

Not sure. The hold-down bolt was loose. Beyond that, it's a mystery


Plugs are new and verified the gap. But they aren't wet.
Does that suggest I'm not getting enough gas in the right places?

I found TDC on #1 and stabbed the dist so that the rotor was pointed to 1 position on the cap.
Someone had previously marked the balancer at 10 BTDC, so that was handy.

 

Coupla things....when you say you have spark, is it a nice snapping blue one or a yeller/orangie type?

And you've verified #1 is at TDC on the compression stroke, yes? I only ask because there are two times when #1 is at TDC.

 

Spark color: I've been concerned that it was a weak yellow thing. Last night I checked the connectors and wiring and afterwards, it seemed like I had a bright blue spark.

I'll double check that. Should I treat "weak spark" as "No spark"?

TDC
When I rotate the engine either by hand or by jumping the starter relay, it blows my finger out. So that should be compression right? This also lines up with the mark on my balancer.

 

If me I think I would treat weak spark as no spark as a way to fix it. But before replacing any IGN parts pull the plug for the IGN box & coil connection to make sure they have good connections. A member found IGN box plug had a bad connection, fixed it and truck runs like new now.


Yes it sounds like you did get TDC maybe you have to advance the timing a little more?
With timing light and a helper, hook timing light up and have helper crank motor over and turn the dist. till you get 10* BTDC and then lock the dist. down tight.


Back to that sludge in the fuel filter thing. If the tank checks out good and you have a fast turn over of fuel then where did it come from?
Sludge in fuel filter is not normal and needs to be looked into and fixed.


You said the carb has fuel in it & the plates are wet but you also said the plugs were dry. Maybe try a little starting fluid or pour a little gas down the carb to see if it will start / run.
Might need to pull the carb apart again for a good cleaning if the filter had sludge.
Dave ----

 

Agree with FuzzFace2. Check the ICM's connections.... distributor connections, sludge, etc.

Weak/no spark is indicative of an ICM going south, coil problems, ballast resistor wire problems, stator problems, etc, and/or electrical connections by all. You have the DSII distributor, yes?

There's numerous troublshooting tests to be had for all problems.

You have a DVOM, yes?

Withe engine off, the air cleaner off, peek down the venturis while blipping the throttle. You should see 2 squirts of fuel when you do this.

 

Some answers to questions above:

DSII distributor.
I am getting two squirts when I hit the throttle.

Update:
Putting a bit of gas right in the carb consistently gets it to start up for a few seconds.

So I am looking at a fuel issue for sure now.
Clearly, I need to clean or replace the tank. And maybe the sending unit is in rough shape too. I'll know more when I get it off.

In order to troubleshoot the cause of the current no-fuel condition, I'd like to isolate things a bit. Can I take a gas can and run a hose from there to the (mechanical) fuel pump?

Also going to pull the carb and give it a cleaning again.

 

Sure, you can use an auxiliary fuel tank like that, it's even a good idea to do so for troubleshooting purposes.

I don't at all recommend doing anything to the carburetor at the same time, though; one thing at a time and one thing only, so you know what you messed with in the event something goes really haywire (or is suddenly fixed, as the case may be).

 

It depends.

If you want to set a gas can next to the truck for troubleshooting in your driveway, have at it. That should work great.

If you want to drive to work, you're going to need a really long hose..

 

I was seriously worried that you were going to give an overly-verbose, technobabble-filled explanation, thanks for the humor.

 

Couple things come to mind.

First you can disconnect the fuel line from the carb and run it into a bucket. Then crank the motor over for a bit and see how much fuel you have in the bucket. If you don't have any fuel pumped into your bucket, you ain't gettin' any gas to the carb and you need to look into the fuel delivery system.

If you are getting gas put the fuel line back on the carb and look at the timing. The traditional shade tree way to get your base timing is to keep advancing it until the starter starts bogging down and then back it off until it doesn't. Then you road test it for pinging. If you hear any pinging retard the timing until it doesn't ping any more and then it should be about right.

Anyway, if it runs smooth on a few shots of starting fluid here and there your timing must be about right. But if the starter spins the motor freely and it runs poorly when you can get it started, then you probably need to advance the base timing a bit.

Last time I replaced a distributor I left a big old manifold vacuum line disconnected and boy did it idle poorly until I figured that out!

Oh, and ctubitus, Some people enjoy KR's techno-babble. I envy his ability 'cause I can't sling it anywhere near as good as him!

 

Dang it.

 

Ran a hose from a gas can to the pump and no go.
Next steps:
How can I test the fuel pump? It's brand-spanking new, but there is always the likelihood I botched the install.
If the pump seems ok, then I need to see if there is some clogging in the carb.


And to acknowledge advice rev'd above, I am definitely looking into the condition of the tank.

 

Just read about "bagging" the line to the carb and cranking the engine to test the pump. That will be tonight's first step.