truck fires but wont idle

[VOoDoO70]

The trucks been sitting awhile for close to a year, truck will crank over but wont idle and Im stumped. Heres the setup 1970 C10 sbc( not stock) with an electric external fuel pump mounted on the frame, coming from an in cab tank, to a 600 Edelbrock carb. No fuel pressure regulator. When I turn the ignition the fuel pump starts humming and shows 6.5 psi on the gauge in the fuel line, then I crank it fires right up but you have to keep your foot tapping the pedal to keep it running. I noticed the fuel filter by the carb does not fill up. As I mentioned the truck has sat for awhile but I since then have replaced the carb with a brand new one, and drained out all the old fuel from the entire fuel system. I even blew the metal line and fuel pump with compressed air. I feel like Im missing something, but dont know what else to look for. This is my current fuel system. Any imput?

[phat69]

The the fuel line off the carb and see how much it flows. You should rewire that pump. solder the connection or at least get the butt splices with the heat shrink. If your 12+ wire is smaller than the lead coming out of the pump it should be replaced with at least the same gauge.

[aerotest]

Idle jets are probably gummed up.

[Coley]

So hang on a second.....
The fuel filter that does not fill up....is not by the carb based on the pics, its down in front of the block right?
Now, the pressure gauge which Is by the carb ends up showing 6.5 psi right?
Try disconnecting the fuel line from the upper gauge (near the carb) and run this into a bucket or gas can and see if the pump starts to fill it up and how consistent the flow is.
I would start with that.....simply troubleshooting.

My two bits.
Coley

[VOoDoO70]

Originally Posted by Coley

So hang on a second.....
The fuel filter that does not fill up....is not by the carb based on the pics, its down in front of the block right?
Now, the pressure gauge which Is by the carb ends up showing 6.5 psi right?
Try disconnecting the fuel line from the upper gauge (near the carb) and run this into a bucket or gas can and see if the pump starts to fill it up and how consistent the flow is.
I would start with that.....simply troubleshooting.

My two bits.
Coley

Yes the fuel filter is down in front of the block, I disconnected the hose right before the fuel gauge going to the carb and ran it into a gas can while I turned on the fuel pump. The fuel pump is NOT the problem it's getting plenty of fuel going to the carb. The carb is spitting fuel as it should when you rev the engine, just cant get it to idle. I tried adjusting the carb mixture screws and idle screw but no change. I feel like it has to be something simple. What else could be the culprit?

[Greasey Harley]

Check for vacuum leaks?

[rockyrivermark]

Too much fuel pressure. Very common prob on edelbrock and brought up here last month.
Get pressure regulator and reduce to 5 psi.
I'd bet that fixes it.
Mark

[WorkinLonghorn]

I'll tell you one thing. If you ever have that v-belt break, there is a good chance that that little plastic see-through filter will be shattered and you will have a major problem. I once bought a car with this set-up and about a month later the belt snapped and broke the filter and my car became a freeway fireball. If they had YouTube back then I'm sure I would have been a star. -BA

[rockyrivermark]

Read this thread. Same prob you have
Many didn't believe that it was a fuel pressure problem but that's exactly what it was
6.5 is too much pressure even though edelbrock specs say 6.5 is max.

http://67-72chevytrucks.com/vboard/s...d.php?t=759963

[VOoDoO70]

Ok update I relocated the fuel filter out of harms way added a fuel pressure regulator and for some reason it does not change the pressure shown on the gauge. The gauge is steady at 6.5psi even adjusting the allen screw up or down while the fuel pump is on priming. I can't get the motor to stay on to adjust the regulator at idle. Also as I try and keep the motor running it will die and spit fuel out of the top of the carb. WTF!

[7 Devils]

Originally Posted by VOoDoO70

Ok update I relocated the fuel filter out of harms way added a fuel pressure regulator and for some reason it does not change the pressure shown on the gauge. The gauge is steady at 6.5psi even adjusting the allen screw up or down while the fuel pump is on priming. I can't get the motor to stay on to adjust the regulator at idle. Also as I try and keep the motor running it will die and spit fuel out of the top of the carb. WTF!

If you rev the motor up off idle and hold throttle position will it stay running at sat 1800 rpm?

[rockyrivermark]

Definitely have to get the pressure down
When at idle do you see gas flooding in the carb?

[VOoDoO70]

I took the carb apart checked the floats they are good, cleaned the screens behind the needle and seats everything is good. The carb was actually clean since its brand new. No flooding in the carb just cant get it to run on its own.

[Aberdare]

This is old school... so check the following:

1) Choke not closing properly. Adjust choke if necessary.

2) Big vacuum leak on engine somewhere. Use vacuum gauge to check. Fix the leak. You may have put the base gasket on wrong or it is the wrong one for this carb & engine combination.

3) Choke pull off setting incorrect. Adjust to factory specs. Carb can get bumped in shipping or transportation and can accidentally change the setting.

4) Fast idle RPM set too slow. Adjust to recommended RPM.

5)Low fuel delivery. Correct delivery to carb. Usually it is a plugged up filter.

6) Electrical or compression problems on the engine. Do complete tune up & diagnosis to correct the problem.

7) Float level set very low. Check & adjust the float level to factory specs.

8) No voltage/ground to the idle solenoid (if equipped). Check for power & ground. Repair the problem as required.

9) Defective idle solenoid. Replace/repair problem as required.

[VOoDoO70]

If I start the engine and throttle the pedal to hold the rpms it will stay running. Once I let off the pedal it dies. Aberdare, Im not sure what steps 3 4 8 and 9 actually mean as far as checking them on my setup to see if they are properly set.

[7 Devils]

Originally Posted by VOoDoO70

If I start the engine and throttle the pedal to hold the rpms it will stay running. Once I let off the pedal it dies. Aberdare, Im not sure what steps 3 4 8 and 9 actually mean as far as checking them on my setup to see if they are properly set.

Have you pulled any of the plugs to see if they are getting foulded? A vacuum gauge would be helpful so you could veriy no leaks or timing.

Dan

[Aberdare]

Originally Posted by VOoDoO70

If I start the engine and throttle the pedal to hold the rpms it will stay running. Once I let off the pedal it dies. Aberdare, Im not sure what steps 3 4 8 and 9 actually mean as far as checking them on my setup to see if they are properly set.

These are not "STEPS" - they are items to be checking... from most common to least probable. This is old school diagnostics... so print yourself off the specifications sheet for your carb, and start checking.

From personal experience I would say that #2 is your most likely culprit.

[rockyrivermark]

Get that fuel pressure down first.
Can't stress enough how edelbrock carbs are funny about fuel pressure.

[VOoDoO70]

Originally Posted by rockyrivermark

Get that fuel pressure down first.
Can't stress enough how edelbrock carbs are funny about fuel pressure.

I went out and bought another fuel pressure regulator as the one I installed previously had no effect on the fuel pressure, Im installing it as we speak. So going down the checklist I starting messing with the choke and discovered if I close the choke and clamp it down the truck will idle! Sounds right too. Once I hit the throttle it will die. Do I need to adust my fast idle screw? The cam and screw are currently not touching unless I manually close the choke by hand. I never have the choke closed but once I did so it actually stayed on. Ive never messed with the fast idle screw how is it supposed to be set?

[Aberdare]

Originally Posted by VOoDoO70

I went out and bought another fuel pressure regulator as the one I installed previously had no effect on the fuel pressure, Im installing it as we speak. So going down the checklist I starting messing with the choke and discovered if I close the choke and clamp it down the truck will idle! Sounds right too. Once I hit the throttle it will die. Do I need to adust my fast idle screw? The cam and screw are currently not touching unless I manually close the choke by hand. I never have the choke closed but once I did so it actually stayed on. Ive never messed with the fast idle screw how is it supposed to be set?

Now... think about this... Choke - What does the choke do? What is its purpose?

... with the choke is closed, the engine idles... what does this tell us? I know what it tells me. -- less air -- same amount of fuel... therefore; idle mixture is incorrect... but WHY is the idle mixture incorrect? Wrong setting? Idle speed? Fast idle? Vac Leak?

Mhmmm... sounds to me like a vacuum leak is your culprit - Item #2.

[CC69Rat]

Originally Posted by rockyrivermark

Get that fuel pressure down first.
Can't stress enough how edelbrock carbs are funny about fuel pressure.

Yep -- the electric FP and Edelbrock carb is the issue. Fuel pressure regulator is a must for those carbs. Too much pressure can cause what youre describing with it dumping gas down the bowls too.

If you read up more on that carb, it will also tell you you'll need a carb spacer or the heat will radiate up through the body of the carb itself and cause vapor lock (fuel is boiling in the bowls)

Not only that, Edelbrock recommends their $100+ fuel pump for it. A stock mechanical fuel pump is too much for a 1406 / 1407. I can only imagine what kind of pressure the electric pump is pushing to it.

I see two options for you my friend -- change to a Holley, or a fuel pressure regulator ( a good one) which negates the benefits you'll see from the electric pump.

[VOoDoO70]

Originally Posted by CC69Rat

Yep -- the electric FP and Edelbrock carb is the issue. Fuel pressure regulator is a must for those carbs. Too much pressure can cause what youre describing with it dumping gas down the bowls too.

If you read up more on that carb, it will also tell you you'll need a carb spacer or the heat will radiate up through the body of the carb itself and cause vapor lock (fuel is boiling in the bowls)

Not only that, Edelbrock recommends their $100+ fuel pump for it. A stock mechanical fuel pump is too much for a 1406 / 1407. I can only imagine what kind of pressure the electric pump is pushing to it.

I see two options for you my friend -- change to a Holley, or a fuel pressure regulator ( a good one) which negates the benefits you'll see from the electric pump.

Ive always been a holley guy, hell I run a holley on my camaro, the truck came with the Edelbrock when I bought it and didnt see a reason to change it at that time since it ran well. I bought another fuel pressure regulator but need to install it, just been tied up at work. I also bought new plugs and wires since its been sitting for awhile. I will update once I get a chance to slap everything on. Thanks for the help

[special-K]

I've been away, just got back, haven't read thread through, but saw the title and first thread. I'm sure there have been many helpful suggestions but let's get our terminology straight for now and all future issues. If people want good help and get straight to the issue, I suggest knowing the difference between cranking over, firing, and running.

From what little I have read here I see your truck cranks over, fires, and starts, but the issue in not idling.
*Cranking over means battery and engine will turn engine. No spark and/or no fuel

* Firing means you at least get some spark and some fuel. No start

* Starting means just that. It's running. If it doesn't, look back to other two

* Idling means sit there and run w/o giving gas

Just trying to help people help themselves with giving correct information to start things in the right direction and get straight to the issue.

[rockyrivermark]

Yep. I put a 1/2" spacer. Cheap. $25. Funny thing I have phenolic at my shop, could have made us easily. Works well.
I have a stock mechanical pump but gauge reads 5 psi so good.
Get the pressure down and report back of that helps.
Mark