Its running a little rough...

[mrandig]

Interesting. Like the Brawler carb, this pump looks brand new also.

I'm going to have some questions in a few for the experts. I don't have time right now to unpack everything but give me until a little later.

 

[mrandig]

Not sure if this car was modified due to heat soak or vapor lock issues, or if these are just random go-fast parts. Thoughts, observations, and decisions so far:

1. Brawler 850 DP carb. Replaced - w/smaller, vacuum secondary 4160. Better street manners and overall response.
2. Holly Strip Dominator intake. Keep - A single plane manifold isn't necessary for this engine and RPM range, but too lazy to replace.
3. Mr. Gasket AL carb spacer. Replaced - w/0.5" phenolic wood. We'll see what this does, if anything, for carb temps.

4. Electric pump (rear). Undecided - "pusher" pump is currently wired for continuous duty; relies on mechanical carb to regulate pressure (otherwise 7+ psi) - will overpressure needle and seat assemblies when engine is not running. It is also incredibly noisy, not to mention mounted upside down.
5. Fuel lines. Undecided - routing of mech. pump to carb fuel line may be contributing to heat problems. Distributor also causes routing issues.
6. Stock pump. Undecided - may have a pressure problem. May fabricate a pair of splices and try each pump separately and then see which one works best. To test the electric pump as a stand-alone, I'll need a regulator, but I should have one somewhere.

7. Vapor canister. Keep for the moment, until there's some indication of a problem.

That's about all of my thoughts for the moment. Any comments or suggestions, please feel free to add.

 

[ckessel]

Great job with the troubleshooting.

 

[mrandig]

I had every -AN fitting except the one I was looking for.

Thanks Amazon!

This is some sort of hinky ****, but it will work. Let's bypass this noisy fuel pump and see what we've got...

(the fuel line is not against the exhaust; it's just the camera angle)

And 3, 2, 1...?

Nope. The mechanical pump isn't working.

 

[mrandig]

I'm going to decide tomorrow which way to go with fuel delivery. Until then, there's three options:

1. Remove electric pump, replace mechanical pump (e.g., M6903)
2. Remove mechanical pump, replace electrical pump and add regulator (e.g., Aeromotive 11203)
3. Keep both pumps but replace, add regulator, replumb, and rewire

I'll leave this here for comments until the morning.

 

[64fury74charger]

Just for clarification here, is the electric pusher feeding the carburetor through the inoperative pump on the motor?
Maybe the pushrod on the mechanical pump is bad?

 

[mrandig]

Just for clarification here, is the electric pusher feeding the carburetor through the inoperative pump on the motor?
Maybe the pushrod on the mechanical pump is bad?

Correct. The electric pusher is feeding through the mechanical pump on the motor. The mechanical pump doesn't have enough suction to pull any fuel from the tank on its own.

Is the mechanical pump totally inoperative? Hard to say yet, but it seems to lower the pressure when the engine is running. Something lowers it, then lowers it more, then lowers it more, until there's hardly any (<3psi).

There probably needs to be more diagnosis on what's going on with the mechanical pump. The current one looks like the $17.99 Oreilly Auto version, so i don't mind ditching the Chinesium for something a little better regardless. I've never come across a bad fuel pump pushrod, but 2024 has been full of surprises so far...

As for the electric pump, it is a certifiable mess. Continuous duty, upside down, small gauge wire (18), no cut-off switch, wired directly into the ignition (no relay), and tied-in with what is probably 3ft of rubber hose. Also, there's no regulator, so it's over pressuring the needles and seats on the carb. I'm sure there's more issues to find, but that's enough already.

Whew. Sorry for the long answer.

 

[64fury74charger]

Correct. The electric pusher is feeding through the mechanical pump on the motor. The mechanical pump doesn't have enough suction to pull any fuel from the tank on its own.

Is the mechanical pump totally inoperative? Hard to say yet, but it seems to lower the pressure when the engine is running. Something lowers it, then lowers it more, then lowers it more, until there's hardly any (<3psi).

There probably needs to be more diagnosis on what's going on with the mechanical pump. The current one looks like the $17.99 Oreilly Auto version, so i don't mind ditching the Chinesium for something a little better regardless. I've never come across a bad fuel pump pushrod, but 2024 has been full of surprises so far...

As for the electric pump, it is a certifiable mess. Continuous duty, upside down, small gauge wire (18), no cut-off switch, wired directly into the ignition (no relay), and tied-in with what is probably 3ft of rubber hose. Also, there's no regulator, so it's over pressuring the needles and seats on the carb. I'm sure there's more issues to find, but that's enough already.

Whew. Sorry for the long answer.

Thank you for sharing your experience and troubleshooting the issues with your car. Sometimes we find things that others have done trying to fix problems and it creates more problems than it solves.

Thanks again for sharing and posting here as this information and your showing how you go about finding and resolving problems will help others here . I am sure you will get these things sorted out.

 

[Runcharger]

Really easy to change to a Hemi delivery, mechanical fuel pump. Take the fire hazard at the back out for now. You can always add a pusher later if the car is too hard to start without it. Make sure to pull the pushrod and check the length of it when changing pumps.

 

[Don Frelier]

I would suggest pulling the sending unit and taking a look inside the tank and look at the fuel sock. Look closely, I had one pick up fibers from the trunk mat and it would plug up the longer you ran it.
Let it sit and it would run fine for a bit.
Got slowly worse and worse.

 

[mrandig]

Thanks everyone for the useful comments. The feedback here has been very much appreciated.

I decided to ditch the previously installed electric pump and go with this package from Mancini Racing - should be arriving later today.

We'll get it installed over the weekend, and then see where we're at.