Hello, I have 73 302 maverick. I have changed the intake and carb to a holly street avenger 4 barrel about 5 years ago. The last time I drove the car was a year ago, which stopped running because of a faulty intake gasket. I drove the car for about a year and a half before it died. The car has 45,000 original miles on it. Today I replaced the gasket and I can not keep the car running, It will run as long as I spray carb cleaner but when I give it gas it back fires through the carb and dies. I think it might be a tuning or timing issue. please help I miss driving the mav.
Might be something as simple as a dirty spark plug or fuel filter/clogged fuel pump. The backfiring sounds like a timing issue, it only takes a few minutes to check the timing and its free if you already have the light(or know someone you can borrow it from) so Id check that first.
I think JPS is onto something. Actually, from what I understand, the reason for the backfiring is that the fuel/air mixture is lean (yes, bad timing could cause the condition, but if you haven't changed the timing, then the likelihood of it being that is reduced). The fact that it runs on the carb cleaner indicates that the mixture is not not getting enough fuel - thus the possible culprit being the fuel pump, or no gas clogged line (as JPS pointed out) old gas gasket not properly seated Mars and Jupiter are not properly aligned Solar Flares and Polar Bears Or ... something else
If you pulled the distributor to change gasket that would be the first thing to check that you got it back in right. Back firing through carb is a indication of improper timing, hopefully you didnt blow the power valve out in the carb.
Thanks for the quick reply! Today I changed all the spark plugs, wires and fuel filter. I forgot how much of a pain in the ass it is to get to the middle spark plugs. I will call a buddy with a timing light.
No you just have to tear carb down and put new valve in, you probably didnt blow the valve but if gas starts to pour out the top of carb when you get it running power valve is most likely the culpert
The fuel filter seems to have a steady flow of fuel. When the car runs on the carb cleaner it runs smooth. I have never been that good at tuning the holly carb. When I do the steps in order according to the manual I can never get just right.
I was thinking of getting a NOS bottled filled with carb cleaner and just spray when the carb starts to die
I am sure what ever your problem is a lot of money will fix it. Probably just something simple. Do you have fresh gas in it?
Old gas may be an issue but.You are getting the backfire due to a lean condition(lack of fuel in proper amounts)Do you have fuel after the filter??? at the carb??? if so you may have a stuck needle not allowing fuel into the primary float bowl(if not filter is plugged or installed backwards).Do you get any fuel out of the carb when you pump the throttle??? check it and see.You have a fuel delivery problem pure and simple.Not to many things in that circuit to check.Good luck!!
if the carb has been sitting for a yr. with the same fuel in it,it "needs" to be rebuilt,metering blocks passages plug up with varnished or old fuel,baseline setting on holley carbs air fuel mixtue screws are as follows, turn screw all the way in til it just seats,back out 1 1/2 turns,as far as the backfiring goes ,as the others have said it's a timng or firing order issue,hope this helps. this is just an after thought,you DIDNT BY ANY CHANCE HAPPEN TO USE A WIRE WHEEL TO CLEAN THE HEADS FOR THE NEW INTAKE GASKETS DID YOU? I MADE THAT MISTAKE ONCE COST ME AN ENGINE,OIL PUMP SUCKED UP A LIL PIECE OF WIRE WHEEL,LOCKED THAT PUMP SO FAST IT MADE THE PUMP DRIVE ROD LOOK LIKE A DRILL BIT AND SNAPPED IT IN HALF.
