Fuel & spark but no start

[redhorseshoe]

So continues the ongoing saga of my poor ol' 73. . . Engine turns over but rarely starts. When it does start, it only idles for a minute or two and then dies. Runs nice and smooth when it's running then it's like someone turns the key off and it just shuts down.
There is fuel getting to the carb which was just completely rebuilt and there is also spark. The spark though, is a dull orange color, not bright blue like it should be. I just replaced the coil today and no improvement at all.
Any ideas???

 

[67EB_in_619]

bad wires? bad battery/alt?

 

[jckkys]

How did it run before the carburetor was rebuilt?

 

[RustBeltRefugee]

Do you have points and condenser ignition or electronic ignition? I had points do something similar to what you are describing. Changed over to Pertronix.

 

[JAFO]

Bad condenser can cause poor spark. The condenser is just a capacitor there to protect the points from burning premature. If the condenser is acting like a short or partial short it would inhibit the function of the points and coil. Fuel, air, spark. Running smooth, then dies sounds like a fuel delivery issue to me, unless the points are closing up or the condenser does something weird when hot. Or you have a loose wire some place in the ignition. Could try feeding the coil 12 volts directly to rule out the ignition.

Divide and conquer. Dumb down the ignition to 12 volts to the coil and if still the same pour gas in the carb.

For spark, you turn it over holding the coil wire with air gap to ground and you see it crack an arch. Should be OK.
Fuel, you could try pouring (small amounts) fuel down into the carb while it idles. If you can keep it running then I would focus on fuel delivery.

1. Stuck needle valve (even though new).
2. clogged fuel filter, which means the fuel in the carb bowl is not resupplied quick enough.
3. You could try routing the fuel from the fuel filter (using a long fuel line) to a jug and then crank the engine. Make totally sure fuel is flowing good.

If fuel is flowing good to the carb and if you pour fuel into the carb and can keep it running, then focus on the carb, needle valve and such.

 

[redhorseshoe]

Definitely a fuel problem. Got underneath and found a flattened fuel hose with a crease in it I somehow overlooked the other 6 times I was down there. Replaced that hose and she fired right up, idled great, responsive throttle, etc. Took it on the road and did great until I tried going up a hill by my house and it started hesitating BAD.
So now the new issue is hesitation/stalling at the top end when it needs more oomph. On the flat ground you can mash the throttle and it picks right up with pretty much no issue, it's only going up that stupid hill.

 

[redhorseshoe]

FYI it acts like a vacuum leak problem I had in an old pickup I used to own but I'm suspicious of that because I've already been having fuel delivery issues./

 

[BroncoBoom]

Carb-a-tators hate steep inclines .
Most will stall during a really steep climb .

 

[SteveL]

What carb is on it?

 

[Bronco Junkie]

When did you last replace the carb filter? Do you have additional filters on your gas line?

 

[JAFO]

To test for an intake leak you can spray something like WD40 along both sides, to temporarily seal the leak. But really, you should be able to keep it running if a vacuum leak, right? Just would not idle good.

Start it and try to keep it running by pouring gas in the carb. If it stays running, it is a fuel delivery issue of some type.

As a teen I had a major fuel delivery issue with a Plymouth Valiant. Me and some buddies had been barreling across a field coming back from hunting. I turned onto a long straight dirt road. Tearing down the dirt road and the engine dies. After some cranking I happen to look in the rear view mirror. Down the road...what is that? Oh, my gas tank! Strap came loose and it fell out from under the car. Couldn't find the strap so we stuck the tank in the trunk and had some gas in a bottle. Rigged up a funnel and a buddy sit in the trunk and poured gas into the gas line (we stuck up through a hole in the trunk) until we got home. Line wasn't long enough to reach the tank in the trunk. Ah the teen years.

 

[redhorseshoe]

Well here's where I'm at now. I found the problem was a broken vacuum diaphragm. It sits on top of the carb and will open the butterfly valve. So I replaced that and all the vacuum lines too, as well as the fuel filter. I also added a clear inline fuel filter right before the fuel pump.

Now it won't even start. There's no fuel getting even up to the new filter I just installed which is what was happening when I replaced the fuel pump. A few days ago this thing was running and I just shut it off and now this.

 

[redhorseshoe]

I just had an idea. If there's a bunch of crap in my gas tanks (original from '73) could that rust/sediment entering my fuel pump cause it to fail? There's about 3 hours of run time on this pump but I know the fuel coming out of those tanks is filthy.

 

[IChaseCoues]

May be the fuel pump. I replaced mine a while back and the engine ran fine that day. A few months later I wanted to start it to run it a little and it wouldn't start. The thing is in the shop on jack stands being rebuilt so I try to start it occasionally just to keep the seals oiled. Anyway it wouldn't start. About 30 minutes of trying to figure out what's going on found me with the new fuel pump in a vice. The thing is locked up and will not pump! So I had to buy a new pump to replace my "new" pump!


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