280zwitha383 Posted February 6, 2007 Share Posted February 6, 2007 I've got a Holley 670 Street Avenger and after a few days it will completely empty out and I'll have to either prime it or pour gas into the float. I've replaced the gaskets but I haven't stopped it. Any ideas? It has to be something fairly simple but I can't figure out what. Quote Link to comment Share on other sites More sharing options...
gretchen/jason Posted February 25, 2007 Share Posted February 25, 2007 Have ya tried taking it off the engine and letting it sit say with some rags under it . Just to look for leaks . I have a demon carb same as a holley uses the same parts at least and after about 4 days of sitting the bowls are about half empty , im leaning towards it evaporating out the float bowl vent tube . I have seen my carb leak some out the venturies after i drive it i am guessing its just pressure that makes it drip . i doubt it could get sucked back into the tank but maybe try pinching off the feed line to see what happens . Jason Quote Link to comment Share on other sites More sharing options...
bjhines Posted February 25, 2007 Share Posted February 25, 2007 Is the bowl vent tube clogged? Quote Link to comment Share on other sites More sharing options...
mamba_888 Posted February 25, 2007 Share Posted February 25, 2007 Could it be a stuck Power Valve? I suggest you open up the carb and give it a go through. Don't know how old it is but the older the more you need to open it up and rebuild it. Quote Link to comment Share on other sites More sharing options...
280zwitha383 Posted February 26, 2007 Author Share Posted February 26, 2007 Well, I went though it on Saturday of week before last. I didn't replace anything, just switched the floats from prim. to sec. The power valve held suction against my thumb for as long as I cared to hold it and I cleaned everything out pretty good. I didn't look at the needle and seat on the power valve because I didn't think about it at the time. Setting the thing on rags is not a bad idea. Where is the vent tube? I started another thread about this in the non-tech board a few days ago because noone replied to this one. Then all of the sudden today all of this... http://forums.hybridz.org/showthread.php?t=119384 Quote Link to comment Share on other sites More sharing options...
PhZ Posted March 3, 2007 Share Posted March 3, 2007 The carburator on my truck is always empty when I go to start it after a few weeks, but the fuel pump prims it up again after a couple turns. Why would it matter if the floats are empty, it should still fill back up after a few turns. Why would you have to prime it? There's where I'd start. How long between starts, a few days or a few weeks? Maybe my truck carb is bad too? Hmmm, it's only two years old and always did this, but I never cared because it refills and starts after three seconds or less. Quote Link to comment Share on other sites More sharing options...
280zwitha383 Posted March 8, 2007 Author Share Posted March 8, 2007 You might have something there. Maybe the fuel pump is lacking also. I have been having a cutoff at 5500+ rpm's but I don't usually take it up much more than that so I haven't really worried about it. If I get in after a couple of days the pump will never catch up I don't think. I've cranked and cranked and eventually I will have to pour gas into the float. Then if I don't put a whole lot in it will sputter like it's about to run out of gas and then bam. I'm in business. Do you have a mechanical fuel pump on your truck or is it electric? Quote Link to comment Share on other sites More sharing options...
PhZ Posted March 9, 2007 Share Posted March 9, 2007 It sounds like your fuel pump can't keep up, if you have a mechanical one, you should rebuild it or replace it. If you have an electric one, you should measure the pressure, it should be around 5-6 psi. If it is not, then you need a better fuel pump. I have an aftermarket electric fuel pump on my Z, it puts out 11psi at the pump by the tank. Then I use a regulator in the engine compartment to regulate it to 5.5psi. I have stock lines and it still pulls strong at 6k. I did have an issue when I first hooked it up, I put a fuel filter between the regulator and the carbs once and it felt like it ran out of fuel above 4k, which is rediculous. So I put the filter before the regulator and no problem since. If you've searched "fuel pumps" on the forum, there is a lot of good information about the pitfalls of a remote pump. They recommend bigger lines if you only run a 7psi pump at the tank, and a lot of people have trouble running a pump in the engine compartment for variuos reasons. More detail: I have a cutoff/primer switch, so when I haven't used the Z for a long time, the bowls are empty, but when I flip the primer switch for just a second or two, the bowls are full again, then the car starts. On the Z it takes a good 6 weeks for the bowls to go dry. Now that I think about it, all these bowls from all these carburators just evaporating into the air can't be good for the environment... Quote Link to comment Share on other sites More sharing options...
280zwitha383 Posted March 9, 2007 Author Share Posted March 9, 2007 Haha, well I'll put a new pump on it. I didn't notice my cutting out until I went from single 2.5" to duals. I used to be able to take it up to 7.5k!!! I did that on accident but it was still pulling.... haha. I have my filter in between the pump and the carb and I guess it should be before the pump to keep crap out of the pump also. Maybe tomorrow.... Quote Link to comment Share on other sites More sharing options...
PhZ Posted March 10, 2007 Share Posted March 10, 2007 Well, the filter sometimes does go between the pump and carburator, my truck is this way. But the Z definately had the filter on the section of the fuel line before the pump. Quote Link to comment Share on other sites More sharing options...
iaconsultants Posted March 11, 2007 Share Posted March 11, 2007 If I remember correct about another diaphram that is under the float bowl on the primary side. Make sure that is not leaking and that it makes the correct gasket type of seal. Also check to make sure your float levels are set correct and that the floats actuate the valves properly. Quote Link to comment Share on other sites More sharing options...
Mikelly Posted March 11, 2007 Share Posted March 11, 2007 You also might want to check your DIPSTICK... Smell for gas, and too much oil... It would suck if you had other issues with that carb and all that gas was going into the heads, down past the pistons, washing the rings along the way, trickling over the bearing (They really don't like gas!) and into the oil... Just a thought... Mike Quote Link to comment Share on other sites More sharing options...
280zwitha383 Posted March 12, 2007 Author Share Posted March 12, 2007 I did smell the oil a few weeks ago for that reason and it didn't strike me as gassy. I was going to replace the powervalve today and poke around a little bit but I got the idea that I was going to spray a little paint. After that I was pooped. Oh well, there's always next weekend. Quote Link to comment Share on other sites More sharing options...
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