Author Topic: Carb. issue....need help. (Read 1423 times)

70 StangMan · « **on:** January, 09, 2012, 01:39:35 PM »

Alright...I put on a rebuilt Autolite 2100 carb. a few months ago. What I'm finding out now is that in order to get the engine to fire and run (after sitting a few days) , a small amount of gas MUST be poured into the top of the carb. or the engine will just turn over and over (forever) without firing. Once said gas is dumped in it will run fine and start over and over. There is gas in the bowl prior to attempt to start (about a 1/2" below the top) and is full after the engine turns over a few times but not fired. Any ideas ????

AzPete · « **Reply #1 on:** January, 09, 2012, 01:49:54 PM »

What happens if you pump the gas pedal a couple times prior to start?

70 StangMan · « **Reply #2 on:** January, 09, 2012, 02:02:05 PM »

Quote from: AzPete on January, 09, 2012, 01:49:54 PM

What happens if you pump the gas pedal a couple times prior to start?

Nothing at all. Same result.

silverblueBP · « **Reply #3 on:** January, 09, 2012, 02:06:06 PM »

Hmmm, fuel pump should fill the bowls. Over the winter, I drain the Holley carb and when I go to restart in the spring, I fill up the bowls through the vent tube and it fires right up. As long as I don't drain the carb, it always fires off even after sitting for a month.

Do you have an electric or mechanical fuel pump?

70 StangMan · « **Reply #4 on:** January, 09, 2012, 02:08:49 PM »

Almost new mechanical pump.

silverblueBP · « **Reply #5 on:** January, 09, 2012, 02:12:07 PM »

Have you check the fuel pressure? Disconnect fuel line and crank it over into a jug if you don't have a gauge.

edit - nevermind, I went back and re-read your post.

AzPete · « **Reply #6 on:** January, 09, 2012, 02:26:57 PM »

Pumping the gas pedal should shoot fuel down the carb. Remove the air cleaner and watch down the carb as you manually pump the throttle linkage. Does it shoot gas? If so, then pumping several times will be nthe same as pouring a small amount in the carb,

Sounds to me like you have a vac. leak. Takes an exceptional amount of gas to counter act the excessive air flow form a leak.......

silverblueBP · « **Reply #7 on:** January, 09, 2012, 02:30:06 PM »

What he said.

70 StangMan · « **Reply #8 on:** January, 09, 2012, 02:51:07 PM »

Quote from: AzPete on January, 09, 2012, 02:26:57 PM

Pumping the gas pedal should shoot fuel down the carb. Remove the air cleaner and watch down the carb as you manually pump the throttle linkage. Does it shoot gas? If so, then pumping several times will be nthe same as pouring a small amount in the carb,

Sounds to me like you have a vac. leak. Takes an exceptional amount of gas to counter act the excessive air flow form a leak.......

Just checked...Yes, when pumping the throttle linkage it does squirt gas into the carb. Could it be the choke is set to far closed ?? Just thinking out loud.

AzPete · « **Reply #9 on:** January, 09, 2012, 03:01:46 PM »

The choke will open enough to allow starting.

If you attempt to start it and pump the pedal numerous times(I mean a whole bunch while cranking the starter), does it start? Still sounds like it is taking more gas to start....because there is to much air. How much black smoke from the tail pipes once it starts?

silverblueBP · « **Reply #10 on:** January, 09, 2012, 03:04:26 PM »

You don't need a choke in Florida! My carb doesn't have a choke.

AzPete · « **Reply #11 on:** January, 09, 2012, 03:05:20 PM »

Quote from: silverblueBP on January, 09, 2012, 03:04:26 PM

You don't need a choke in Florida! My carb doesn't have a choke.

When you go from start to explode....no choke needed.....

70 StangMan · « **Reply #12 on:** January, 09, 2012, 03:12:43 PM »

Quote from: AzPete on January, 09, 2012, 03:01:46 PM

The choke will open enough to allow starting.

If you attempt to start it and pump the pedal numerous times(I mean a whole bunch while cranking the starter), does it start? Still sounds like it is taking more gas to start....because there is to much air. How much black smoke from the tail pipes once it starts?

Tried pumping like I was getting paid for it, I tried holding the pedal all the way to the floor, I tried not pumping at all (all on different occasions) trying to find the magic formula...but the results are always the same. Nada unless fuel is added to the carb.

70 StangMan · « **Reply #13 on:** January, 09, 2012, 03:14:08 PM »

No black smoke that I can see in the mirror

silverblueBP · « **Reply #14 on:** January, 09, 2012, 03:16:46 PM »

Get a Holley.

AzPete · « **Reply #15 on:** January, 09, 2012, 03:18:57 PM »

Convert to a 4100.....

Has the car backfired at all......power valve could be bad.

70 StangMan · « **Reply #16 on:** January, 09, 2012, 03:44:55 PM »

Never a back fire

70 StangMan · « **Reply #17 on:** January, 09, 2012, 03:48:22 PM »

Quote from: AzPete on January, 09, 2012, 03:18:57 PM

Convert to a 4100.....

Has the car backfired at all......power valve could be bad.

I really need to make this one work...$ wise. I want a aluminum intake w/4 barrel but that will have to wait till the money situation gets better.

AzPete · « **Reply #18 on:** January, 09, 2012, 04:04:55 PM »

What was the reason for getting the rebuilt card to begin with?

70 StangMan · « **Reply #19 on:** January, 09, 2012, 04:19:46 PM »

I couldn't tell what all the PO had done to make it still run. Leaked at the acc. pump. ( gas would puddle up on the intake) Broken fresh air inlet for the choke. Sh*t wired up here and there. I found a very good deal on a re-man. so I decided to start fresh and eliminate all the problems (so I thought)

AzPete · « **Reply #20 on:** January, 09, 2012, 04:23:51 PM »

You may need to go back and check timing and all.....a basic tune up check....to see if anything was out of adjustment to make the previous pos work.

70 StangMan · « **Reply #21 on:** January, 09, 2012, 04:43:15 PM »

Quote from: AzPete on January, 09, 2012, 04:23:51 PM

You may need to go back and check timing and all.....a basic tune up check....to see if anything was out of adjustment to make the previous pos work.

That is kinda what's confusing me. When I bolted on this one it fired right up and ran but now it won't. I did run the pcv hose to a inlet on the intake that was capped off. (the other used to go into the base of the old carb but this one has no input). I'm wondering if that screwed things up. That is the only thing different that I can think of.

AzPete · « **Reply #22 on:** January, 09, 2012, 04:47:41 PM »

That could......it is said that the cylinders that it flows to may be running leaner than the rest since it is an air source after the carb. Might have to seek a spacer with a PCV port.

70 StangMan · « **Reply #23 on:** January, 09, 2012, 04:50:33 PM »

Quote from: AzPete on January, 09, 2012, 04:47:41 PM

That could......it is said that the cylinders that it flows to may be running leaner than the rest since it is an air source after the carb. Might have to seek a spacer with a PCV port.

I did before doing what I did. 4V seems to be the common one. But I might want to keep looking. Maybe cap off the inlet and see if it makes a difference I'm thinking.