I'm losing patience.. Carb or fuel pump issues?

[Jimbotronics]

I know some of you have answered my quetions concerning carb issues over and over - now I see what's happening but can't figure out why and it's driving me crazy. The carb is fairly new - purchased from a board member. Shortly after installing I couldn't get gas to stop running into the bowl after I killed it and had the carb totally rebuilt. It seemed like that was the problem because afterwards it didin't do for a while. Now it's doing it again, it'll even die coming to a stop if you don't keep the engine reved. I checked the fuel pressure and it reflects about 5.5lbs. Could it be that the pump is bad and is intermitent? What I do know is that I've got $300 bucks invested in a used carb and I'm ready smash it and I'm not even sure it's the culprit...

[Longhorn Man]

What kind of carb?
Has your fuel tank ever been inspected/cleaned?
My money says there is dirt/rust entering the carb and making the needle valve stick. (that regulates the amount of fuel permitted into the bowls)

[GMC AMI]

It may be a pin hole in the float and it just will not float. A sinking float will permit the fuel to keep on flowing the same as dirt in the needle seat.

[Robert1970C20rstbukt]

I have the same problem. Whan I had the Quadrajet on my truck, gas came out the hole that the accellerator pump rod sticks out of, and the carb floods at idle, but not at WOT. Not sure what's wrong with it. Now I have an old Carter AFB on it and when you're at a stoplight or you're sitting with the tranny in gear and the brakes applied, it stumbles, then dies then it's a ***** to start up again. Not a good thing to happen in the middle of an intersection! If I have it in nuetral it runs great. Then when you shut the engine off gas drips off of the side of the carb. I'm gonna try a fuel pressure regulator, and I hope like hell that it works.

[Jimbotronics]

It's a holley 600. Mine and roberts issues are exactly the same. Haven't had the tank cleaned but the guy that rebuilt the carb said everything looked extremely clean (that's all he does is rebuilds carbs). He thought it had something to do with the fuel pressure as well.

[Robert1970C20rstbukt]

Mine's stated above, a carter AFB. The tank on my truck is clean, just surface rust. All lines are clean, new fuel filters, carb has been cleaned inside and out. Floats don't have any holes in 'em. Tomorrow I'll get the regulator and see what happens, but before that I'm gonna check the fuel pressure again. Yesterday it was like 6psi and that should be normal.

[Jimbotronics]

Robert - Let me know if the regulator does the trick so I can do the same. Althoughk, I don't have an in-line fuel filter so I guess that would be a good thing to do at the sametime.

I hate messing with carbs - i know crap about 'em.

[3 on the tree]

Get yourself one of those clear glass aircraft style filters with the replaceable elements. Then you can see what's going to your carb. Also, I had a 780 Holley do the same thing and it was a blown power valve. Has your rig had a backfire or sneeze prior to this problem-that will blow a power valve 9 times out of 10.

[Robert1970C20rstbukt]

Jimbotronics

I'll let you know tomorrow after I buy the regulator. I checked the pressure about 15 minutes ago and it was around 6psi, almost the same reading I got before so I'll pick one up and give it a shot. The inline filter is a good idea so no rust, etc gets to the filter in the carb and plugs it up.

[Jimbotronics]

Good idea 3 on the tree! No backfire just started flooding. Thanks Robert, let me know what the regulator does for ya. Cheers, Jim.

[GMC AMI]

Originally Posted by Jimbotronics

I don't have an in-line fuel filter

Jim not ragging on you but this is asking for carb, trouble. I have a hard time
thinking a fuel reg. is going to help but stranger things have happened. Did you ever see how much dirt is in the pump gas? I put gas in 5 gal. cans for my tractors and it is quite unbelieveable how much dirt is left at the bottom of the container sometimes. I would ask the guy who rebuilt it to take a quick
check of the needle seat and float adjustment just to make sure. Power valve
also will cause too rich condition. Did the carb. guy check this one out during rebuild? I hope you are back on the road soon.

[bobs409]

Did you have the fuel line unscrewed shortly before it started flooding? The reason I ask is I once changed the fuel filter (inside carb) on my '72 Malibu and when I tightened the line back on, a small sliver of a thread came off and got stuck in the needle/seat. I went for a ride and all was fine for about 5 miles but then I had to race the engine at every red light to get it home.

The piece was so small, you almost needed a magnifying glass to see it! It doesn't take much. The needle/seat is where I'd start looking.

[Jimbotronics]

He said he went through everything thoroghly - and it's ran fine for about two weeks.

Haven't had the fuel lines off, but I'll check/clean the needle seats and see that that does.

[jakeslim]

funny you should post this! I just went through this within last coupel of weeks. I had just installed a rebuilt carb and an electric fuel pump. The pump was supposed to pump around 5.5 or so. Gas kep spilling over the top. I even pulled the carb and cleaned it out thinking the float was stuck(as mentioned above).
The fix? Fuel regulator. I installed it and set it at 5.0 and problem fixed. No more fuel spilling out the top through vent holes. This should fix your problem. Cost of regulator was $23 bucks at auto parts store.
Mine was doing everything yours was doing so I would think this is your problem. Also, I thought it was dirty fuel etc, even bought one of those clear fuel filters as suggested but all along it was just the fuel pressure.

jakeslim

[Jimbotronics]

Good info Jakeslim - I'll prob do like Robert and install one. At a minimun it will eliminate the probability. Although I hope it cures the issue..

[jakeslim]

Jimbo,
Just saw you live in Rockledge. I'm "vacationing" in Rockledge this holiday. Small town(Rockledge), small world.

later,
jakeslim

[Jimbotronics]

lol - cool you'll hafta drop by and have a cold one. I work at Patrick so it's a bit of a drive but worth not having to deal with the hassle of Melbourne.

[Jimbotronics]

I installed the regulator today - drove it around town for about twenty minutes happy as a kid in a candy store... no stalling, no hesitation, no flooding. Then I'm a pulling into a convience store and there it goes it again same ol same ol... I cut the engine off, removed the breather, and looked down in the carb. Sure enough fuel is justa flowing. Tapped lightly around the carb a bit with a pair of pliers (all i had with me) and it stopped. Drove around another twenty mins with no issues. Leads me believe I need to install a filter and check the tank again.. gonna leave the regulator installed though.

[Robert1970C20rstbukt]

Went to AutoZone to get a pressure regulator and they didn't have one so now I gotta check oreillys and carquest tomorrow.................

[rockguy]

Jim
If you are running with no in line filter you will probably continue to have the problem. If when you tapped on the carb it stopped that is a clear indication that your float was stuck. Normally that is because of dirt. Try the fuel filter first. Its also cheaper. Steve

[Jimbotronics]

I went to discount auto and they didn't have one but Autozone did..lol

[Jimbotronics]

Rockguy - There's no inline filter at the moment, that'll definitely be next step.

[Robert1970C20rstbukt]

What did you ask for at AutoZone? They wanted all the info for my truck(1970, 3/4 ton, 350, 4bbl, etc) and they said they couldn't find one. I asked if they even had any in stock that I could look at and they said no. If you have the autozone part number for it I'd appreciate it.

[Jimbotronics]

He started going through that the same questions and I said, look all I want is an adjustible fuel regulator - shouldn't make a difference what it goes on. Then the guy says "OH, those are on isle three."

[Jimbotronics]

However, as Mike stated in #11 dirt is likely the problem. Have you tapped around on the carb? A good in-line fuel filter will be my next step.