Dry Fuel Filter - no fuel to carb (86 C10)

[ninety6]

Hey guys... finally got back to working on my C10 after a summer break (building a deck).

When i got it earlier this year i got it running, but, if quit on me after a few runs up and down the driveway. i figured the old fuel clogged up the carb (oops), as after that no fuel was getting into the Carb, but it would run find on starter fluid for a few seconds.

So, I've drained the tank, put in 5 Gallons of fresh gas, and cleaned/rebuilt the carb. Truck will run fine if i pour gas into the throat for a few seconds until that gas it out....

However, the fuel filter is dry. So, no gas is getting into the fuel filter and therefore into the carb. I removed the check-valve in the fuel filter as i thought that looked strange, but that didn't help (i'll put it back in once i get this working).

With the fuel line disconnected, the pump shoots fuel out. I didn't measure it, but it poured all over the floor when i first cranked it after putting the carb back on (and no reconnecting the fuel line, oops!).

So i need some tips on what to check next? Is it possible the pump is too weak to push even the air out of the filter/carb to start taking fuel, but when not connected to the carb still shoots out a lot of fuel? Or is something in the carb somehow still clogged and not letting the fuel push its way in to the carb?

thoughts? Thanks!

[ninety6]

forgot to mention. prior to all the above, truck was sitting for 3-4 years... .

[Dead Parrot]

Assuming a mechanical fuel pump and Qjet carb with internal filter.

As a test, get a Fram G3 filter, some 3/8 fuel hose and put the filter on the suction side of the fuel pump. Remove the existing filter, reconnect everything and see if it runs.

Some folks will say you aren't supposed to run one on the suction side but after using my special talent of cross threading QJet fuel filter housing threads too many times, been running one there for many years.

[geezer#99]

Take the line off at the carb, stick the end in a bucket and crank it until you get good flow.
Then hook it to the carb, dribble some fuel into the carb and it should fire up.

[ninety6]

yes, mechanical pump into stock quadrajet. (305).

I have good flow when the line is off the carb.... -- made a huge mess on the floor when i forgot to hook it up! it does fire up with gas in the carb -- but fuel doesn't continue flowing in...

[geezer#99]

Check the inlet filter.
Might be plugged or installed wrong.

[ninety6]

inlet filter is good: Fuel line --> fitting --> rubber gasket --> filter --> spring --> carb.

i tried both the old and the new filter, they don't even get wet with fuel. I remove the check plug and spring to make sure that wasn't stopping the flow. just seems really weird to have gas pumping out when the fuel line is off the carb, and nothing going through when it is...

[geezer#99]

Next!!!
Needle/seat installed wrong or stuck.

[ninety6]

is the needle/seat the next hop in fuel flow?

Basically the same thing happened before i rebuilt the carb. I may have to suck it up and take the top of the carb back off and check. I used the new seat and needle from the rebuilt kit-- i did notice that when the float is down, the needle isn't 'up' (due to the gap in the little clip -- but both old and new were like this) -- but i'm assuming the fuel pressure is supposed to push the needle up, and then it's pushed back down when the float rises.

i did make sure that the passage between the fuel filter area and the inside of the carb were clean. -- as in carb cleaner sprayed through without trouble.

i might try this with everything assembled and see if anything comes in to the carb (if i could even see it..)

Oh -- i did try blowing some air into the fuel filter area - but it was nearly impossible to tell where it came out -- some definitely came out the little port right next to the fuel filter inlet, but it didn't really help me...

[geezer#99]

The float controls the needle. Not fuel pressure.
Float drops, fuel comes in.
Float rises, fuel flow quits.

You likely have your float set wrong keeping the needle seated(no fuel flow).

[ninety6]

The float moves up and down properly -- (and i adjusted it to 13/32 per the rebuilt kit and a couple other sources -- it was at like 20/32nd or something, way off).

But, when the float is DOWN, the needle isn't pulled up -- if i tighten that tiny clip, then the needle would move up. I read elsewhere that the fuel pressure essentially pushed the needle up, and that if you didn't even use the clip, it wouldn't operate any differently. I wasn't real sure about how true that was.

So, with that said, is it important that the top of the needle is essentially in contact with the float at all times, even when dry? Basically, the old one i pulled out and the new one installed as it came -- the clip leaves a little space between the top of the needle and the bottom of the float. (i made sure to install the clip correctly on the flat part of the float and not the hole).

If the fuel PSI isn't enough to push the needle up, then this could definitely be the source of my problem. -- if it relies fully only the float to open as well as close...

[ninety6]

Ok, i took my better air compresser end, and put it on low pressure (maybe 10PSI), and put it sealed into the fuel inlet. So the air when through that, the filter, and into the carb. i heard a little pop -- i'm wondering if i somehow mashed the needle into the seat during assembly and got it stuck. the little pop was likely the needle unsticking (it sounded like a tiny cork).

Now it runs nice and smooth it seems -- but idles REALLY high!

So, on to the next task... but at least it's running again! i'll keep an eye on it, hopefully i won't have to remove the carb again.. and now i have fresh gas!

[ninety6]

False alert on the high idle. It was actually the rod going from the carb to that rubber diaphragm on the firewall. It was suck "back" -- loosened that up and idle is good. Runs MUCH better than before the carb rebuild... now it needs brakes, fluids, belts, oil change, and me to finish buffing it and she'll hopefully be ready to roll!

hopefully a cold start tomorrow works as it should!

[Little Flo 77]

Great thread, now I am curious to hear if the cold start worked as it should have?

I have a 77' C10 Stepside that does not like to cold start. Pour a little gas in the carb and I can get it to start up. Once I get the engine warmed up it will start every time.

[ninety6]

Originally Posted by Little Flo 77

Great thread, now I am curious to hear if the cold start worked as it should have?

I have a 77' C10 Stepside that does not like to cold start. Pour a little gas in the carb and I can get it to start up. Once I get the engine warmed up it will start every time.

Multiple Cold starts the following day were perfect, started right up! I think my idle might be a little low, but she's still running. I think the really fast "idle" - where i mentioned the rod stuck -- i think thats the cruise control diaphragm. Hopefully it's still good after sitting multiple days or week, time will tell!

On the carb rebuild video i watched, they mentioned a condition similar to what you mentioned -- on the bottom of the carb there are little plugs that are hammered in to the carb. They keep the gas in the bowl from draining out. If they work themselves loose over time they let gas drain out of the carb slowly causing there to be no gas in the carb the next time you start. Perhaps thats your problem?

Check out this video at the 19:40 mark. He shows the plugs and talks about how to fix them.
https://www.youtube.com/watch?v=oLpUqS9zrP8

[geezer#99]

Originally Posted by Little Flo 77

Great thread, now I am curious to hear if the cold start worked as it should have?

I have a 77' C10 Stepside that does not like to cold start. Pour a little gas in the carb and I can get it to start up. Once I get the engine warmed up it will start every time.

Fix your accelerator pump and adjust your choke and it'll start at 40 below.

[Little Flo 77]

Originally Posted by ninety6

Multiple Cold starts the following day were perfect, started right up! I think my idle might be a little low, but she's still running. I think the really fast "idle" - where i mentioned the rod stuck -- i think thats the cruise control diaphragm. Hopefully it's still good after sitting multiple days or week, time will tell!

On the carb rebuild video i watched, they mentioned a condition similar to what you mentioned -- on the bottom of the carb there are little plugs that are hammered in to the carb. They keep the gas in the bowl from draining out. If they work themselves loose over time they let gas drain out of the carb slowly causing there to be no gas in the carb the next time you start. Perhaps thats your problem?

Check out this video at the 19:40 mark. He shows the plugs and talks about how to fix them.
https://www.youtube.com/watch?v=oLpUqS9zrP8

I too have read and watch a few videos of what you have just mentioned about those plugs. I haven't had time to really dig into the problem yet. That will happen this days off hopefully. Start with the easy trouble shooting first and go from there.

[Little Flo 77]

Originally Posted by geezer#99

Fix your accelerator pump and adjust your choke and it'll start at 40 below.

This is definitely something I am going to look into. I appreciate the feed back fellas.