Demon 650 stalling
#1
Demon 650 stalling
Hey Guys,
I have a 91 Firebird with a 68 Impala 350 sbc in it that has a Demon 650 carb on it. I bought the car maybe 2 months ago and it drove home problem free for 2hrs of highway. I registered it yesterday and today it started having stalling problems. It will be driving along (35ish) and start gargling as if it were sucking air or not getting enough fuel, the first couple times it did this then died. My brother and I figured out that when it did this (usually at steady mid throttle) you could let off to idle for a bit and it would recover and you could go another minute or so... When it starts dying, the oil pressure drops like crazy, is this caused by the dropped rpms or could this be a related problems? The fuel pressure at idle is about 3.5psi which seems solid for a mild street motor, the regulator and gauge are in the engine bay so i can not watch them while driving. After dying, the car will start right back up after a couple seconds of waiting but there will be little or no fuel in the sight glass on the carb. It seems that it just doesnt have enough fuel for constant throttle or there is an air leak. Where can I start? Fuel pump? Test for air leaks? The car seems to respond fine to heavy acceleration but not consistent pull of fuel.
Thanks in advance,
Tyler
I have a 91 Firebird with a 68 Impala 350 sbc in it that has a Demon 650 carb on it. I bought the car maybe 2 months ago and it drove home problem free for 2hrs of highway. I registered it yesterday and today it started having stalling problems. It will be driving along (35ish) and start gargling as if it were sucking air or not getting enough fuel, the first couple times it did this then died. My brother and I figured out that when it did this (usually at steady mid throttle) you could let off to idle for a bit and it would recover and you could go another minute or so... When it starts dying, the oil pressure drops like crazy, is this caused by the dropped rpms or could this be a related problems? The fuel pressure at idle is about 3.5psi which seems solid for a mild street motor, the regulator and gauge are in the engine bay so i can not watch them while driving. After dying, the car will start right back up after a couple seconds of waiting but there will be little or no fuel in the sight glass on the carb. It seems that it just doesnt have enough fuel for constant throttle or there is an air leak. Where can I start? Fuel pump? Test for air leaks? The car seems to respond fine to heavy acceleration but not consistent pull of fuel.
Thanks in advance,
Tyler
#3
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Car: '86 Bird, 96 ImpalaSS, 98 C1500XCab
Engine: LG4, LT1, L31
Transmission: 700R4, 4L60E, 4L60E
Axle/Gears: 3.73 Tors, 4.88 spool, 3.73 Eaton
Re: Demon 650 stalling
sounds like either a fuel filter plugged or the pickup sock in the tank clogged.
#4
Re: Demon 650 stalling
oh wow, those are two things I hadnt considered yet... where would the filter be located? Best bet to check it and replace completely? I would assume it needs one even if that isnt the problem.
#6
Re: Demon 650 stalling
I raised the float height and have a new fuel filter for a carb setup that I am ready to put in but am limited by New England weather, don't feel like lying in mud/snow/ice in the dark to replace it so I am waiting to use a friends shop. It has been running much better and the raised float height and addition of a real exhaust (used to be true dual glasspack side pipes) have definitely helped it out. I plan on doing the filter and re-adjusting the fuel pressure and then i think it should be good to go. I don't think pump only because 1) no bad noises from it and 2) no hard-starts
#7
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#8
Re: Demon 650 stalling
OK, I set it to half height in the sight glass earlier but the pressure is currently below 6. Will the filter affect the pressure or should I set the fuel pressure now even if I haven't done the filter yet?
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