sandman825 Posted January 29, 2010 Share Posted January 29, 2010 Hey guys I've been having a problem with my '73 with Weber DGVs thats really got me stumped. Its kind of a long story but I would really appreciate your help. It started out when the accelerator pumps stopped spraying, so whenever I stepped on the gas pedal the engine would just sputter out and die. It would idle fine once it got started though. So I figured it was clogged up with junk since the car had been sitting for a very long time. I took them apart and rebuilt them, replaced fuel filters, and also blew out the fuel lines with compressed air. This worked for a little while, but after a few starts of the engine, (Its not being driven, just getting worked on) the pumps quit spraying again. Soooo, I dropped the gas tank and removed the carbs to clean them out thinking maybe gunk was still getting pushed through the line from the tank and into the carbs. After re-installation I had the same effect as before. It worked for a short period then the accelerator pumps gave up again. I've repeated this process once more, dunking the carbs in those big cans of cleaner, but I'm still at square one. I read a thread by a guy having the same problem but for the life of me I can't find it again, sorry. But he solved his problem when he found out the coarse filter on the electric fuel pump was clogged with garbage. I've replace mine already but still the same problem. So do you think maybe I still have crap in my fuel system somehow? My uncle proposed that the aftermarket/universal electric fuel pump might be creating too much fuel pressure, filling the bowls too high and causing the floats to stick in the closed position. Does this sound plausible? Any help would be appreciated, thanks. Quote Link to comment Share on other sites More sharing options...
theghosttanker Posted January 31, 2010 Share Posted January 31, 2010 The 73 has two fuel pumps, the electric by the tank and the mechanical on the motor. The electric fuel pump was added to help clear vapor lock problems and is not needed at all, and if it not working properly it can give the problems you describe. The system of relays and wires that control the electric pump is a PITA, and if you are working on the car you may not have it running consistently. Webers are indeed very sensitive to fuel pressure although the sticking float problem is one I've never encountered. I suggest you try running the car exclusively on the mechanical pump. Remove the electric one and just pipe fuel straight to the underhood filter and then to the underhood pump.Webers run great on the mechanical pump alone. Quote Link to comment Share on other sites More sharing options...
MikeyZee Posted February 1, 2010 Share Posted February 1, 2010 Hey, my son had the same problem with his 72 240z and the Weber DGVs. His problem turned out to be a dirty tank. We ended up having his tank boiled out at a radiator shop for about $100 and he has not had the fuel delivery problem again. When the fuel level got low enough it would suck up the dirt from the tank and clogged the filter under the hood. There were issues like the rear carb would not spray, the front would. We switched the carbs and they worked for a few minutes then the rear carb would stop working. Just blew my mind cause I knew we had just put a new filter on it. Like I said it was just when the tank got low. For the pump, you can just rely on the mechanical fuel pump and see if you can get it to run consistent. The electric pump was just to fix a vapor lock type of issue. The DGVs only call for a few pounds or pressure maybe 4-5psi. You could measure the fuel pressure at each carb and different places before and after the fuel filter and stuff. Quote Link to comment Share on other sites More sharing options...
MikeyZee Posted February 1, 2010 Share Posted February 1, 2010 http://forums.hybridz.org/showthread.php?t=138772&highlight=DGV+fuel+pressure Quote Link to comment Share on other sites More sharing options...
sandman825 Posted February 2, 2010 Author Share Posted February 2, 2010 That thread sounds just like the problems I'm having. I tried dropping the tank once before to clean it out, but I just put some...idk degreaser or something in there to swish around. After that I just shoved a vacuum in it to pick up the solids I could see. I'm guessing I'll have to try your more thorough cleaning method. Might as well as remove the electric fuel pump and see how that goes too. Thanks alot, I appreciate the help. Quote Link to comment Share on other sites More sharing options...
MikeyZee Posted February 2, 2010 Share Posted February 2, 2010 You could also try feeding the carbs from a gas can instead of the tank. It may help eliminate certain parts of the system. I unhooked the fuel supply from the under hood filter and ran a hose into a jerry can to help diagnose. Good Luck! Quote Link to comment Share on other sites More sharing options...
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