Stalling out-- help troubleshoot please

[SHX669]

It looks like air in the top part of your fuel filter -might not be a problem if the filter was horizontal but in vertical position there is no fuel in the line to the pump - and that is a rotary vane pump --- bet you have about 1/2 tank of gas just about the level of the fuel in the filter. You probably have to lower your pump intake to the level of the bottom of the tank - or make sure you always have more then 1/2 tank of gas.
I'm not a fan of rotary vane pumps in a Bronco.
SHX

 

[BoulderBronco22]

Update on where I am at.

This morning I replaced the coil, igntion pickup, and I actually put a brand new ignition module on it since the one Viper gave me had some use under it. I figure either way-- its only about 75 bucks of new parts that it wouldn't hurt to replace.

Took it out for a test drive and less than a half mile from my house, it started to stumble... and then stalled. Had a couple of backfires and had a difficult time keeping it started to get home. I did however check the carb float level at the point of when it started stalling. I pulled over and was actually even leaning towards the float check screw. Took it off and started to rock the Bronco and I could not get any fuel to come out. I also checked it again when I got it back to the house in the driveway on even ground and did the same thing-- no fuel coming out.

When I checked the float levels earlier this week on a cold engine... it was set perfectly and just a little bit of rocking would cause fuel to drip out. It seems as though this might be the problem-- the float level is getting stuck when the engine is running. It aso seems like it has gotten worse over time. It started out doing it after driving it a relatively far distance and now I can't get a mile from the house before it starts to do it.

So I am not real comfortable with carbs and wondering if there is anyone that knows why the float level is sticking. I have read a little bit about the needle and seats getting gunk in it that would cause it to stick and that sometimes the bowl should be replaced as well. Any carb experts care to weigh in on my next move here?

Thanks!

 

[707Bronk]

From my experience you should have a coarse filter before the fuel pump and another fine filter closer to the carb.

Putting a finer filter like the one it looks like you have as a pre-filter might be negatively impacting your fuel filters ability to suck the fuel...might also check to see if there is air in the filter while the rig is running as that might further be starving your pumps vaccuum side.

Might try just moving the fuel filter till after the fuel pump and give it a run.

And, when I have had problems like you are describing (stumbling and stalling) it has usually been either sticking floats (or also common is that they have pinhole leaks in them and keep them from floating), gummed up carb, or clogged fuel filter.

I made the mistake of not flushing the lines enough and ended up just re-gumming my freshly rebuilt carb. If you used any sort of thread sealer it might take a while for the residual to cycle through.

If it were me, I would try moving the fuel filter first. If that doesn't work, then rebuld the carb, or find one that you can do a temporary swap. And don't think that just because the filter looks clean it is, if you want to verify blow air through it and compare how much restriction there is compared to a new one. I've wasted a lot of time (once) thining that the filter was clean because it looked clean.

 

[Pa PITT]

... At the dodge stearership I worked at. One of our tech put a new fuel pump in a pickup . It went inside the tank. But he'd gone to dinner an left a pink fender towel inside the tank to dry it out after he'd wash it out.
.. That towel kept swishing around and would land over the fuel pump inlet shutting down the Truck. Found it & got the restriction out and that truck ran great.
...

 

[blubuckaroo]

Where is the fuel pressure gauge?

When you checked the float level, was the engine running normally? You would want to check it when it's screwing up.

Take it for a drive. When it screws up, turn off the key immediately, then pull over, and check the fuel level in the fuel bowl.

When it dies, can you hear the pump running? That pump is normally pretty noisy so I doubt you'd miss it. Good idea to make sure the tank's clean. And get rid of the pre-filter. You only need the one at the carb.

 

[BoulderBronco22]

Quick update: dropped the tank and cleaned out real good. Also air pressure tested it and it holds air. Took the carb off and bench set the float. Went to start it up to adjust the float and it won't turn. Realized the pump is now not working. It's getting power but won't turn on. Called JEGS and they felt that an electric pump probably isn't best for my scenario since it pushes fuel. They felt that it would struggle to pull fuel the short distance to the pump and the fuel really should be gravity fed. So now they are exchanging it for a mechanical pump. As soon as I get that, I am hoping I will be able to maintain pressure and have a functioning Bronco again.

 

[BRONCROB]

Make sure you have secure connections after installing the mech pump or you will suck air and be back with questions.Sounds like you may have a leak upstream now or poor elec pump wiring or connections.What circuit is it running off of?

 

[broncnaz]

Ive been running a carter pump in about the same location actually mines slightly farther away from the tank plus I run dual tanks. and I have had no issues for the past 30 years. Yes electric pumps do push fuel better than they pull but your not pulling that far. I know people that have them mounted in the engine compartmetn and have no issues. Sounds like you may just have a bad pump or something is wrong with your wiring.

 

[Mikey]

If you are having problems with the float, it may be the float itself is leaking (if brass or hollow plastic) or saturated (if black foam). Been there, done that. You can tell if you keep trying to lower the float level and it just won't.