Author Topic: Flooding Carby!! (Read 6395 times)

Petey · « **on:** December 18, 2012, 04:28:26 pm »

I'm having trouble starting the f/back after it's been running for a while. Turn off ignition, when I try to restart it, seems like the carby is flooding and starting up is very difficult. When I do get it to run, it blows fuel out the exhaust and runs with lots of missing and takes a minute to settle back into steady idle. If I turn off the engine and try to restart, same thing happens all over again!
New Holley Street Avenger 4 barrel with electric choke fitted to the engine six months ago. Used to run fine until the last few weeks (has been sitting for a month prior to that) and nothing has been changed since. Can't be a fuel blockage as it runs fine, even when started cold after a week sitting in the garage, but it sure as hell hates to be stopped and restarted!
Any ideas what the problem is?
PT

IGALOP · « **Reply #1 on:** December 18, 2012, 05:23:28 pm »

Idle screw adjustment maybe. Screw them in till they gently seat then back them out approx 1 1/2 turns is usually a good start point.

69candy · « **Reply #2 on:** December 18, 2012, 06:43:52 pm »

sticking needle and seat???

GLENN 70 · « **Reply #3 on:** December 18, 2012, 08:09:52 pm »

Its the needle and seat ,will have dirt in it .Are you running a filter .You will have to take out the needle and seat ,then tap in your hand and blow clean ,refit and reset float levels .You need to take out side plug to get level right ,just so a small amount of fuel comes out when you give the car a side shake ,have a rag to catch fuel overflow .Start with needle screwed down , unscrew plug check level ,if low put side plug back in and do again and again to right . Good luck,would help if someone could do this for you . cheers glenn .

Frank70 · « **Reply #4 on:** December 18, 2012, 08:54:41 pm »

Yeah, I reckon needle and seat stuck. while it is running rough, give the carby a solid whack with a plastic mallet and if the problem goes away, then you found the culprit.

Cheers,
Frank.

GLENN 70 · « **Reply #5 on:** December 18, 2012, 09:01:44 pm »

Frank sometimes you can TAP the screw on top of the needle and seat and it will help but if its a bit of shit floating around in fuel bowl it will came back .To do this job you really need to know what you are doing .easy when you know how to do a problem when you dont .

Petey · « **Reply #6 on:** December 18, 2012, 10:14:00 pm »

Thanks guys,
Tonight I couldn't get it to run on all cylinders after it had been sitting since last night. In fact it ran so rough it stalled and would not start again at all.Strong petrol smell under the hood and no doubt the engine is flooded. I looked down the throttle and pulled the cable to full open and the amount of fuel squirting into the bowls was way more than before.
I have had the carby apart before to put smaller jets in and it ran fine until the last few weeks, so checking float levels and adjusting needle and seat should not be too difficult. Always prepared to give it a go anyway.
Thanks again and I will let you know if that is the problem.
PT

GLENN 70 · « **Reply #7 on:** December 18, 2012, 10:23:09 pm »

Two ways to tell 1st take air cleaner off ,look into carby after trying to start engine you will see fuel dripping in or over flowing out of breather tubes ,2nd take out side plug and if fuel comes out this means float is too high or needle and seat is the problem . hope you did not go to small in jets .

Petey · « **Reply #8 on:** December 19, 2012, 06:30:14 am »

Went down two sizes from standard jets supplied when new. The carby is a 770CFM on a 347 stroker and I thought it might be a little too big. Was definitely running rich before and seemed to be better with the smaller ones 70 primary and 73 secondary.
PT

griff · « **Reply #9 on:** December 19, 2012, 08:50:50 am »

speaking from experience a few times... absolutely needle and seat problem as these maintain your fuel level in the bowls, regardless of whether its a 10 year or 10 day old carby. youve got to have a decent inline filter to stop small particles lodging within the needle tip, if this happens the fuel will just keep pouring in under fuel pump pressure.
ive had this happen twice, in particular last year after starting it up at 10pm in a hospital outdoor carpark, bloody raining of course to really piss u off, started to drive out and it stalled, the fuel stench was ridiculous so popped the air cleaner to see fuel streaming down thru the carby and no doubt filling the intake quite nicely. so there i was with no freaking torch, screwdriver in hand pulling the carby apart and cleaning the needle and seat. next day i installed an inline filter on the fuel pump inlet. never had a problem since and recent inspection showed no sedimentation in the fuel bowls so the filter works well.
lesson: if its gonna happen itll be at the most inconvenient time and place.

Macka · « **Reply #10 on:** December 19, 2012, 01:35:54 pm »

Pete, it does sound like its getting too much fuel. Check the needle and seat first and power valve. Do you run a filter?

Also do a plug chop and check each plug to see how they have been burning. If its doing it now and running way too rich when it starts up and then burns things off a bit when it gets hotter could also be a problem here. A few things you can check is air to fuel ratios on a dyno or changing jets and going to a hotter plug type. Best to get someone in the know to do it. Let us know the outcome.

69candy · « **Reply #11 on:** December 19, 2012, 06:15:45 pm »

Didn't forget to tighten up one of the jets?? JusT saying. Seen stranger things. If it has brass floats. check to see they do not have a pin hole in them.

GLENN 70 · « **Reply #12 on:** December 19, 2012, 07:52:51 pm »

A 770 is a bloody big carby for a 347 ,a 670 would have been the right one if spinning to around 6200 revs . I have a 670 on my 347 runs great good on fuel and has good top end power up to, well off the 140 mph speedo anyway. 6200 rpm top gear with 3.25 ratio and 15 inch wheels . ps only twice and runs low 12s all day .

66 Stang · « **Reply #13 on:** December 20, 2012, 11:34:22 am »

Can anyone recommend a good inline fuel filter to be installed before the fuel pump, what brand and code.

Frank70 · « **Reply #14 on:** December 20, 2012, 01:10:15 pm »

Quote from: 66 Stang on December 20, 2012, 11:34:22 am

Can anyone recommend a good inline fuel filter to be installed before the fuel pump, what brand and code.

Aeroflow billet one or Holley chrome one . Or this :

http://www.ebay.com.au/itm/UNIVERSAL-GLASS-FUEL-FILTER-CHEV-FORD-HOLDEN-CAMARO-S9245-/400345894901?pt=AU_Car_Parts_Accessories&hash=item5d36798ff5

Personally I dont like the Ryco plastic ones from a fire hazard point of view, but as long as it's placed away from exhaust , they are prob fine too.

Cheers,
Frank.

Frank70 · « **Reply #15 on:** December 20, 2012, 01:13:03 pm »

Actually I just realised you were asking about a filter BEFORE the fuel pump.

Can't say I use one and most people don't on a mechinical pump. One after the pump should be all you need.

Unless you are running an electric pump and/or fuel injection. Then just one like a Falcon runs should be OK.

Your standard sender will have a small screen filter in it.

Cheers,
Frank.

GLENN 70 · « **Reply #16 on:** December 20, 2012, 01:51:54 pm »

A ryco inline filter is fine, part number Z153K its for 3/8 fuel line that you should be running .Fit between pump and carby not before pump .

Petey · « **Reply #17 on:** December 20, 2012, 10:04:19 pm »

Thanks guys, all fixed! Took the primary needle & seat out and gave it a good blow out and light oil. was working fine and slid up & down so reinstalled and adjusted float levelto the bottom of the sight window. Started up first go and after a little adjustment to the idle and choke she runs sweet.
I do have a Summit Racing large in line filter between the fuel pump and carby. All the lines and fittings are 3/8" so I think all is covered.
Appreciate all the helpful information. Now to find some time and nice weather to go for a cruise!
PT

GLENN 70 · « **Reply #18 on:** December 20, 2012, 10:10:24 pm »

Good to hear ,i always carry a flat blade screwdriver and spanner for that reason ,holley carbs are known for that problem .

Macka · « **Reply #19 on:** December 20, 2012, 10:29:26 pm »

Good job Pete.

evan · « **Reply #20 on:** December 20, 2012, 11:16:34 pm »

Here's a tip:

Next time it happens (& it will), smack the top of the needle & seat with a spanner, hammer, whatever! I never bother removing it any more.

Evan.

Flooding Carby!!

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Author Topic: Flooding Carby!! (Read 6395 times)