1976 Bronco 302 ... CARB BACKFIRE!!!Help!!!

[Sourjack89]

Had some recent work done on my 76 Bronco...alternator, water pump, thermostat etc...a few of the spark plug wires got disconnected. Carb was also rebuilt at this time. Hooked everything back up today and it will crank but not start at all, not even on a couple cylinders. After I sprayed starting fluid in the carb it made a loud backfire sound...what gives? 41,000 original miles - this bronco is starting to become the BANE of my existence.

 

[bronconut73]

Check your firing order.

 

[bronconut73]

Is this showing the whole firing order....?
Well it shows most of it, lol

 

[B RON CO]

Hi, after double checking the firing order, maybe you didn't give the fuel pump enough time to fill the fuel bowl. Look in the top of the carb, engine off, hold the choke open and open the throttle. You should see two nice accelerator pump squirts. If you don't get an accelerator pump squirt, either there is not enough gas in the carb, or the accelerator pump circuit is messed up.
If you do get a pump squirt, make sure the choke is closed. If you removed the distributor, maybe it was not installed correctly, and you have to set it up on #1 from the beginning. Good luck

 

[half cab]

Yup sounds like several crossed plug wires or that carb build was questionable.

 

[Broncobowsher]

With the work done, crossed plug wires. Something going to the wrong hole.

 

[No Hay]

My '76 has the 351 cam firing order. Check for that.

 

[Sourjack89]

Hi guys - thanks for all the tips!!! I will try going back to square one with the plug wires. Will also check the pump shot...

 

[Rustytruck]

Make sure the center coil wire at the distributor is properly seated at both ends.

 

[DirtDonk]

Did you do the work at your home, or was this work performed at a shop? If shop, did it run to get home? If at home, is there any chance the distributor got removed during the work? Or was it just the wires.

What about disturbed wires around the engine? Any loose or missing wires, or a disconnected connector at the back of the engine? Do you know you're getting consistent spark? The spitting says that you're at least getting some. But it's hard to tell the difference between bad timing, and only an occasional spark.

It'd be just Bronco-typical though, if the ignition module decided to take a dump right after you did the totally unrelated work. That's how these things roll...
Every time I washed and waxed my car on a weekend, the next Monday something would die and keep me from starting, or it would run like crap.
Just the nature of the real world I guess.%)

Paul

 

[Sourjack89]

Done in the driveway by a mobile mechanic...SO my mechanic says he rotated the distributor in order to replace the water pump. Now I have to figure out what position it should be in for the correct timing to start and run, what do you guys suggest?

 

[Sourjack89]

Also this is a first start after carb rebuild, how do you suggest to fill the fuel bowls? Does cranking achieve this? Do I need a shot of starting fluid to jump start things?

 

[Rustytruck]

avoid using starting fluid. make a small funnel out of aluminium foil or use a plastic squeeze bottle and put fuel down the carb fuel bowl vents on the top of the carb. (2 holes about 3/8" in diameter on top of the carb) it should hold a little less than 1/4 cup of fuel. don't spill fuel all over the place or a backfire will light it all up. Clean up any spills and let it dry up before starting the engine. Start the engine outside and have the means to smother and put out any fire.

 

[B RON CO]

Hi, look at a firing order and distributor diagram. The vacuum canister should be in the front, and #1 on the distributor cap should be at about 1 o'clock, and the rotor basically pointing at the brake master cylinder.
I would not use starting fluid.
The carb should fill by itself, by cranking the engine. If you crank the starter 20 to 30 seconds there should be enough fuel. Hold open the choke and see if the accelerator pump squirts. That will tell you you have fuel. These older carb engines may need a couple of extra pumps on the gas pedal to get going, especially if they haven't run for a while.
On my Bronco I could easily pump the pedal 4 or 5 times to get it fired up after it sits a few days. My 66 Mustang, just hit the pedal once to set the choke, and it fires right up.
Of course if the ignition timing is way off you have to get it in the ball park.
Good luck

 

[Skiddy]

Done in the driveway by a mobile mechanic...SO my mechanic says he rotated the distributor in order to replace the water pump. Now I have to figure out what position it should be in for the correct timing to start and run, what do you guys suggest?

call him back out and have him retime it

 

[half cab]

call him back out and have him retime it

This/\/\

Say he had to rotate the timing to install a water pump?