280zwitha383 Posted February 20, 2007 Share Posted February 20, 2007 If I can get a few quick ideas I'll try and tackle this tonight. Anyway I have a street avenger 670cfm and recently the primary float bowl is draining into the engine and causes bad starts. If I let it sit for a few days I have to either prime it or pour gas into the float. I've adjusted the accelerator pump with no luck. It seemed like this happened after I changed out the jets but I've swapped jets out again and still no change. I've also changed the gaskets. The only other thing I can think of is maybe the power valve has blown out (I haven't checked it) but I'm not running noticeably richer so I really don't know. Any help? I posted this in the troubleshooting/gen. info. forum and noone replied so I thought maybe someone would see it and have an idea. Thanks in advance. Quote Link to comment Share on other sites More sharing options...
jnjdragracing Posted February 20, 2007 Share Posted February 20, 2007 I have seen the primary seep gas when the float level is to high. Hopeflly you are adjusting the float level correctly. I have always removed the sight glass / brass plug. Cranked the engine and watch the fuel level. I always set mine a little blow the sight hole, then I press on the fender and some gas should trickle out. Adjust the fuel regulator to about 6 - 7 psi, then with a screwdriver and 5/8 wrench turn the float adjustment to achieve this setting, while loosen the top then turning the wrench. Adjust down for less gas and adjust up for more gas. You will need to keep the top snug while turning but not to tight. Hope this makes since. If the float level is set correctly and it contiunes to leak gas, then the needle seat is not sealing. Could be trash or bad needle seat. Hope this is some help. John If I can get a few quick ideas I'll try and tackle this tonight. Anyway I have a street avenger 670cfm and recently the primary float bowl is draining into the engine and causes bad starts. If I let it sit for a few days I have to either prime it or pour gas into the float. I've adjusted the accelerator pump with no luck. It seemed like this happened after I changed out the jets but I've swapped jets out again and still no change. I've also changed the gaskets. The only other thing I can think of is maybe the power valve has blown out (I haven't checked it) but I'm not running noticeably richer so I really don't know. Any help? I posted this in the troubleshooting/gen. info. forum and noone replied so I thought maybe someone would see it and have an idea. Thanks in advance. Quote Link to comment Share on other sites More sharing options...
280zwitha383 Posted February 20, 2007 Author Share Posted February 20, 2007 That would make it empty out though? Quote Link to comment Share on other sites More sharing options...
grumpyvette Posted February 20, 2007 Share Posted February 20, 2007 the setting the float level suggestion is valid, Id also check and most likely replace the power valve ,ESPECIALLY if the cars EVER BACKFIRED or COUGHTED back, but Ive got a few questions, (1) first how do you know the gas is draining into the intake?, (2)and how do you know the float bowls are empty? (3)whats your fuel pressure at the carb? (4)have you tested the needle and seat valves for crud/leakage (they are a high probability? (5)are you useing a GOOD fuel filter? (6)are you useing a return style pressure regulator? (7)when you let the car sit,have you pulled the sight plugs to verify the bowls empty I really wish you were closer, because this stuff is easy to diagnose (hands on) (8)whats the carbs vacuum reading at idle, at what rpm? Quote Link to comment Share on other sites More sharing options...
GeeZ Posted February 20, 2007 Share Posted February 20, 2007 I glad I not the only person that had problems with Holley carb, though I don't have any anwers. Quote Link to comment Share on other sites More sharing options...
280zwitha383 Posted February 20, 2007 Author Share Posted February 20, 2007 the setting the float level suggestion is valid, Id also check and most likely replace the power valve ,ESPECIALLY if the cars EVER BACKFIRED or COUGHTED back, but Ive got a few questions, (1) first how do you know the gas is draining into the intake?, Well, it's got to go somewhere. I don't know where else it would go. (2)and how do you know the float bowls are empty? Well, I don't know for sure how much gas is in them but when I start it after a few days of sitting I pour a substantial amount of gas into the primary bowl, pump it and it fires up pretty easily (3)whats your fuel pressure at the carb? I don't know. I'm just using a stock mechanical fuel pump I think for an '85 Silverado (don't know if that matters) (4)have you tested the needle and seat valves for crud/leakage (they are a high probability? No, I looked at them earlier and I actually switched them (put the primary on the secondary and vice versa). How would you go about testing them? (5)are you useing a GOOD fuel filter? Good question, I don't know what brand of filter it is but you can see through it. It was pretty cheap I know that much too. (6)are you useing a return style pressure regulator? No, just running a stock fuel pump (7)when you let the car sit,have you pulled the sight plugs to verify the bowls empty I really wish you were closer, because this stuff is easy to diagnose (hands on) Yes, everytime it won't start I pour fuel into the primary bowl (8)whats the carbs vacuum reading at idle, at what rpm? I got about 12psi today, don't know exactly what rpm but close to 800. I've never got more than 12 psi at idle and I can't really affect the psi by turning the idle mixture screws (and never have been able to) I took both bowls, floats, and metering blocks off and cleaned and inspected. My power valve will keep suction for as long as I was patient enough to hold it it just occured to me hours later that it has a needle and seat on the front of it which could be a potential proble, but everything else looked pretty clean. The only other deviation I had was when I pulled off the gas inlet on the primary bowl the little copper/bronze filter did not have a gasket on it and the one on the secondary inlet did. I had never taken the inlets off before and unless I dropped it without knowing I have never had a gasket on it. How does the accelerator pump not continually leak into the intake. For that matter why do the jets not continually trickly into the intake. Holley carbs have so few crucial parts that I've never really paid much attention to how they work, just swapped stuff out. Quote Link to comment Share on other sites More sharing options...
280zwitha383 Posted February 20, 2007 Author Share Posted February 20, 2007 Oh yeah, it's been a long time since I have backfired out the intake. I had my timing way off. It backfires pretty often the last couple of days because I went over a curb that I didn't know was there on a "off ramp". But my carb problem has been going on for a few months. I just got tired of messing with it. The more I think about it, it seems to me that it almost has to be the accelerator pump because that is physically the lowest thing in the bowl and if it was the power valve or something else how would it drain out so much that there is no gas where the accelerator pump is. If there was I would be able to pump the gas and start my car but that doesn't work. I just don't see how all of it would come out unless it was siphoning. Quote Link to comment Share on other sites More sharing options...
grumpyvette Posted February 20, 2007 Share Posted February 20, 2007 its SOUNDS like a blown power valve to me! but like I said this stuff is easy to diagnose hands on, since your not all that carb rebuild skilled Id suggest replacing the power valve and gaskets first and throw the clear fuel filter in the dumpster, and get a QUALITY fuel filter the stock one from a 1985 corvette can be adapted fairly easily Quote Link to comment Share on other sites More sharing options...
280zwitha383 Posted February 21, 2007 Author Share Posted February 21, 2007 If the power valve will hold suction against your hand how can it be blown? I know there is a needle and seat on the other side of it and maybe that's not sealing but I still can't understand how it can drain all the way down. Quote Link to comment Share on other sites More sharing options...
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