New edlebrock help

[BigRed Beast]

My son's truck, a '72 Blazer.

We've been through a few carbs in the past two years, so we finally broke down and bought a new Edlebrock 1406--600cfm w/ electric choke. it's on an Edlebrock manifold, stock 350, mechanical fuel pump with a 38 gallon fuel tank.

Bolted it on, started right up, a couple adjustments and he's off. Less than a week later, he's broke down in the school parking lot, no start, gas pouring out of the carb. I should also note that those are the same symptoms of the Quadrajet we just replaced.

It's his daily driver--or was--so I can only repeat what he said he observed prior to the break down. He mentioned that it was hard to start when warm; that he had to play with the accelerator when coming to a hard stop to keep it from stalling. His tach indicated about 7-800 rpm at idle.
Also, we are in the Denver area, so altitude is above 5000 feet.

First, am I looking at a carb issue, or is there another culprit? Second, if it is a carb issue, are the stock float settings suspect, and is the Quadrajet similarity just that--a coincidence?

I know you guru's have some thoughts, and perhaps need more info to help trouble shoot...fire away!

[Turkey nest]

I have a solution! I know there are several technical reasons why your having this issue but I will give you what worked for me. I have the same carb and had the same issue read thru some post and decided to try the easiest solution I added an inline fuel pressure regulator dialed it into 4.5 psi and it took care of the warm start issue as well as at idle fuel dumping problem. My truck starts better eccelerates better and way better fuel mileage. Bought the regulator at O'reilly auto parts for about $35.00 bucks. Hope this helps.
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[Tom Vogel]

sounded like a fuel pressure issue to me too.

[jaros44sr]

sounds like that may be the culprit,read somewhere on here, probably the engine section, that these quadrajets do not like alot of fuel pressure. regulater seems like the cheapest and easiest place to start

i think it might have been as low as 4 psi, or off road at 2psi

[AlaskaMatt]

5 psi max for the fuel pressure. I agree with the rest, too much fuel pressure.

[BigRed Beast]

Heading to O'Reilly. $33.99 before tax for the regulator. Let y'all know in about an hour!

[BigRed Beast]

Installed a Mr. Gasket fuel pressure regulator just before the fuel filter. Started the truck on a setting of 3.5, it ran, slowed, sputtered and quit. Went to start again and had fuel bubbling up from the float overflow ports. Set the regulator to 0 to see if it continued to flood and it did not. Moved it up to 1 and lost the battery (between trying to restart and the hour long tow home, we ran it down). Got the battery on a charger now, so we'll give it another shot in about an hour.

[Turkey nest]

I should have mentioned this before but now I'm thinking the fuel pump might be the possible issue.
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[FoxHound]

I had the same fuel leak problem from the exact same carb. What I did was put on a fuel pressure regulator (like the other guys are saying), re-calibrated the floats, and installed a spring-loaded 4wd needle and seat set. This took care of the problem. Also make sure nothing is clogging the carb (if your son's blazer has an old gas tank and he runs it to almost empty, it could be picking up sludge from the bottom of the tank). Just some things to think about, hope this helps.

[BigRed Beast]

Charged the battery and gave her a crank with the regulator on 2. Got it started, but it wasn't pretty--ran rough., so I'm guessing it had just enough fuel to start. Less than a minute of run time, sputtered out. Upon attempted restart, gas through the float vents again, so we shut it down. I'm going to see if resetting the floats will do anything, and may put a call into a local shop to see if they any suggestions.

Keep you posted.

[Nothinghead]

When you installed the carb, did you just throw it on, or did you tune the floats and everything else? Did you set the choke per the directions, and set the float distances?

[BigRed Beast]

If I had to hazard a guess, I'd say nothing was done to the floats and minor adjustments to the choke. My son and his friends put the carb on. His friends have quite a bit of experience with automotive in general, and old cars in specific, so I have a tendency to think that they did things right. The fact that the truck started and ran well for 2-3 days after the install kind of confirms it.

But, since I'm the guy who gets to tow the truck, it fell to me to figure it out. I went through the instructions and didn't see anything about setting the floats and only minor instructions about the electric choke. I made a visual inspection and the choke appeared to be wired correctly.

Guess we'll be playing with it this weekend...

[Nothinghead]

The directions from the manual are here:
http://www.google.com/url?sa=t&rct=j...h0KZjo9ymkG4bA

it goes into detail on the tolerances for everything.

if you click that link, it will start to download a PDF of the manual. It's legit

[cleszkie]

If it ran fine for a few days, that right there means that all of the tolerances and settings are probably OK. Sound like you got some gunk in your jets. I used to run a 1406 and learned that it didn't take much gunk to significantly affect its performance. Everytime it started acting like yours, I pulled it, cleaned it, and it worked fine again. Got tired of babying the 1406, so i swapped in a Q-jet and have not had issues since. If you keep the 1406, I recommned a fuel filter before and after the fuel pump, in case its your fuel pump thats sending fragments into your carb. Good luck.

[tubbedII]

Since this problem is happening to multiple carbs and the regulator isn't fixing it, I'm leaning towards particles in the fuel. I'd pull the carb and give it a good cleaning and reset the floats. Then toss in a new filter and maybe even try to clean the tank...

This is what worked with my holley...

[ERASER5]

When my new Edlebrock did that, I found dirt under the needle valve. I am not sure how or why there was dirt, but it was certainly there. A few days later it happened again, then never again, so far. That was a bunch of years ago. New steel line from the pump up, new glass filter (I changed it to a metal one later), new chrome made-for-Edelbrock line to carb, new carb. No idea where that dirt came from.

[BigRed Beast]

Totally frustrating...brought it to one of the neighbor's (a local city mechanic) and could not duplicate the flooding.

We took a reading on the fuel pressure and dialed it to 3.5 psi. Hooked the fuel back up, cranked it and it started right now. Dialed down the electric choke, dialed down the idle to about 800 rpm, put the kid in it and had him run it around to get it to operating temp before he brought it back. Shut it down, waited a few minutes and started it up--again, no flooding, a little harder to start, but nothing like it had been. The only observation the mechanic made was to install a spacer between the carb and the manifold to eliminate heat potentially boiling the fuel.

I guess I'm going with the dirt at the needle valve theory. Don't know when or where it got some crud in there, nor do I know when it got out of there--maybe when we cranked it with the fuel line disconnected? We had dropped the tank to install a new sending unit about a year ago, so I'm sure there isn't a ton of stuff in the tank.

Not real happy, would have preferred some gaping problem. Now, it'll feel like we're rolling the dice everytime he drives somewhere. Bummer.

[ol'blu72]

I would not stop there. It sound like you are all right and have some junk going through the carb. This will come back and be an intermittent problem if you dont at minimum put on new fuel filters. You should have one just after the tank and one after the pump. I would probably also pull the carb and clean it out with some carb cleaner.

[BigRed Beast]

Good idea on the secondary filter. I'll do that later today.

Any ideas as to why the beast is reluctant to start when it's warm? Is that a boiling gas issue, hence installing a carb spacer would help?

[D.PASSMORE]

My elderbrock did the same after a few weeks of street driving. Put a 4x4 needle/seat and when I looked at the floats. Man were they off. I think getting tossed around in shipping mess up the floats. I then calibrated w/ needle and and spring kit. No problems since. BTW - I used a elderbrock mech. fuel pump too.

[Ole Beater]

Hard start could be the timing is too advanced. You could try retarding it a little or maybe moving the vacuum advance hose to the ported unported connection on the carb.