Guest ottodoc Posted April 25, 2014 Share Posted April 25, 2014 rebuilt a vac. fuel pump on a 28 chevy and its drawing raw fuel into the vacuum line.any thoughts on how to correct this condition?while tank is in "fill mode", car runs rough and will load up and stall if not taken to a high idleonce tank is full and float toggles off the vac. port car smooths out till next fill cycle.tank does have .040 orifice in vac port.also has small tube where wiper vac. is attached.putting a small clear hose on this port attached to vac. gage, one can watch raw fuel weep into hoseduring fill cycle. Link to comment Share on other sites More sharing options...
oldford Posted April 25, 2014 Share Posted April 25, 2014 Sounds like the float is not adjusted correctly. Maybe rises too high before shutting off the valve, or the valve is not closing...Frank Link to comment Share on other sites More sharing options...
sambarn Posted April 25, 2014 Share Posted April 25, 2014 If gas enters the vacuum line, the valve is leaking. Either alignment or needle valve. The .040 retrictor. Shouldn't that be on the fuel fill side? Link to comment Share on other sites More sharing options...
rsb Posted April 25, 2014 Share Posted April 25, 2014 It sounds to me like one of the following possibilities:1. The float cracked, filled with fuel, and sank (most common)2. The float is not installed properly on the hook3. The float valve is sticking or leaking. Trash in valve.Regards,Ron Link to comment Share on other sites More sharing options...
GLong Posted April 28, 2014 Share Posted April 28, 2014 Sometimes the springs that the 'teeter-totter' levers are held in place with are too stiff. Take the top off the tank, and confirm the float is not full of gasoline. If it is not, then lift the float on it's guide, watching the levers and valves at the top. Sometimes the float can be pushed quite a bit higher than it should before the levers [the teeter-totter] will go over center and close the vacuum valve and open the vent valve. If the springs are new, stretch the spring a bit to weaken it. In the rebuild kits from one of the Stewart Warner tank guys, his directions state that the springs may need a slight stretching to weaken them. Hope this helps.GLong Link to comment Share on other sites More sharing options...
Guest ottodoc Posted April 28, 2014 Share Posted April 28, 2014 thank u on the replies I will try stretching the springs slightly. the float is new and I lapped the 2 brass valves as good as possibleif I hold either valve closed I cannot blow air thru them so I believe that is ok I checked the flapper valve and it holds as well.If I am understanding about the springs, if they are to strong it allows the tank to fill too much before the valves toggle off,correct? Link to comment Share on other sites More sharing options...
rsb Posted April 28, 2014 Share Posted April 28, 2014 (edited) I suppose you could always drain and remove the tank, then slowly fill it with a funnel through the fuel inlet. You could then observe when/if the float closes the vacuum valve. They used two types of Stewart tanks on the 28 chevy. One had the springs and 'teeter-totter' action as mentioned and you should hear it click when the valve closes. I assume that's the one you have.http://books.google.com/books?id=BtYbqYNbg0QC&dq=dyke's%20automobile%20vacuum%20tank&pg=PA165#v=onepage&q&f=falseRegards,Ron Edited April 28, 2014 by rsb (see edit history) Link to comment Share on other sites More sharing options...
hddennis Posted April 29, 2014 Share Posted April 29, 2014 Howard Dennis Link to comment Share on other sites More sharing options...
Guest ottodoc Posted April 29, 2014 Share Posted April 29, 2014 to howard, that's a great little booklet on the pumps. unfortunately I cannot blow it up far enough to read it. it may just have some good tips on this trouble im having. could you advise me on how to get a copy?to rsb, yes I do have the teeter-totter type pump. gonna give the spring stretch a try. it may be the answer to the trouble im havingif the tank fills too full before switching off. Link to comment Share on other sites More sharing options...
GLong Posted April 29, 2014 Share Posted April 29, 2014 Before stretching the springs. [since it's so darned difficult to 'un-stretch' them] I'd lift the float up and down several times and watch the action of the springs. levers, valves etc. It's a fine balance of lever movement vs spring tension, with a dash of friction thrown in for fun. Once you opperate the float up and down a few times, you will find the spring that is just a bit too stiff. I found this by holding the float up. Then used a small screwdriver or pick to gently 'help' the appropriate lever to 'trip' and close the suction/vacuum valve and open the atmosphere valve. Just operate it several times, you will be able to see what needs adjustment.GLong Link to comment Share on other sites More sharing options...
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