Best Mechanical Fuel Pump

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71Duster

71Duster

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Currently running an FBO "special" mechanical fuel pump on my mild 340. Twice this has happened now.

After a WOT then off and just rolling the car starts to stumble smoke and then die. Had the air cleaner off on the side of the road and the carb is pukeing fuel bowls are way over full. This has happened on 2 different carbs. Had the bowls off and no crap inside and checked the reuseable fuel filter all good there.

No gauge so no idea what fuel pressure this pump makes but its supposedly ported and polished inside etc etc.

I'm done playing with the pump at any rate. What mechanical pump to feed a mild 340 pushing maybe 350-380hp would you recomend that doesn't need a regulator.
 
I run a carter high volume pump, which I belive is actually now (owned) made by edelbrock, they work good and are rebuildable.
 
Looking at summit kinda leaning towards the now Edelbrock street pump thats supposed to be 6psi and not need a regulator. I have all AN lines so it should match up good. Holley also has a similar version but at 6.5-9psi.
 
Sounds like the floats in your carb are set to high. Or there is a problem with the

float needles and seats.

What kinda carb are you running? The fuel level should be at the bottom of the fuel bowl

level check plug. Side of bowl (Holley). Do you have a carb manual very helpful.

Your pump is just a regular Holley with AN fittings nothing fancy.

I have the same pump from FBO.

1973 Dart Sport 340 8.0 1/8 mile
 
I had good luck with the Carter mechanical on my 410c.i with 850dp.Summit sells them for around $70.
 
Hard to belive it's the same problem with 2 different carbs and not the pump and only does it after WOT. Both carbs are Demons and floats are set correctly as per FBO instruction on carb one and the engine shop on the other.

This isn't a regular occurance but dieing in mid traffic while leaving a trail of smoke and trying to get a flooded out car started still sucks.

When the pump was sold to me I was told it was ported/polished inside as they never flowed from factory the numbers they claimed due to casting flash etc.
 
71Duster, I run the same FBO pump that you are running and I had the same problem, but not quite as bad. After a hard blast on the loud pedal the car would die when I came to a stop, the difference is that mine would start.

I could see the rear bowl on my Holley was overfilling (clear site plugs are great). I would adjust the float, test drive it, all would appear fine and it would do it again. I pulled the rear needle and cleaned it thinking it was small pieces of junk causing the problem.

Finally, I got it adjusted so the fuel stays just at the bottom of the site plug hole. It is definitively a trial and error deal, and to get it right you must flush new fuel into the rear bowl (mash the loud peddle). Mine has worked fine now for more than 600 miles.
 
Mine just did it again out on the highway but this was the worst one yet. After the first round of posts I reset the floats right at the bottom of the windows and its been fine for about 100miles, went out on the highway drove like a dream went to a little car meet and when I left nailed it on the on ramp and settled in at 60mph and the car was surgeing. Thought it was odd but figured I'd look when I got home as it was 15mina way and I had no real tools.

Came to the first stop light and the car dies as soon as I let off the throttle. Got it running after about 5 -10min had to hold the throttle wide open and checked under the hood sure enough carb was wet with fuel and it had a small puddle on the intake I mopped up. Got the car running again but it wouldn't idle for crap. Bucking surging and popping through the exhaust pulled into the residential street and it cleared up and ran just fine again.

Checked the floats at home sitting right at the bottom of the windows aagin, idled good etc. Going to check the fuel filter and bowl again for crap but this is a new tank that was just cleaned out this winter, 4 year old braided hose, a new carb this summer as well.

What I find odd is how long it took to clear up this time. I have a good re-useable fuel filter on the car so I don't think its crap in the needle and seat but the fuel tank also has a sump in it which might mean I suck more crap up on a street car?
 
This IS odd.

As much trouble as you are having you should eventually see "junk" if that is the problem.

But the odd thing is that WOT seems to trigger it. Mechanical pumps "pump" by means of the spring in the pump. That is, the cam "cocks" the pump arm, and the actual "pump" is when the spring pushes the arm back down. What this means is that WOT should NOT affect pump pressure.

Regardless, my next step would be to "rig" a pressure gauge and see what you actually have.
 
It's a Demon carb only been on the car about 3 months maybe, it also did it to my previous Demon.

Might order a new fuel feed log for the carb with a built in gauge but the problem is I'll never seen the gauge while driving and I can idle and rev the car all day and never duplicate the issue.

My main concern with the pump is I have no idea how exactlly it was modified internally but before I completely condem it I also thought that how long it flooded for was bizzare.
 
I,d get a new Carter mechanical pump for the cost and less headache.I ran one on my 410sb with 850dp,car ran 10,s.This was with the factory 5/16 sender into 3/8 fuel line.(yes I was schocked)LOL.
 
You could probably go to napa and get there "best" stock replacement one and run it with no problems, I don't think a stock pump will run out of fuel for a street car that's only doing short hi rpm blasts.
 
67Dart273 said:
This IS odd.
...But the odd thing is that WOT seems to trigger it. Mechanical pumps "pump" by means of the spring in the pump. That is, the cam "cocks" the pump arm, and the actual "pump" is when the spring pushes the arm back down. What this means is that WOT should NOT affect pump pressure.
Click to expand...

Sorry I'm going to hijack, but hopefully this helps us understand the problem.

I had this same issue as I described in one of my previous post in this thread. I'm using the same FBO pump, with 3/8 pickup and 3/8 line all the way to the carb. The reason I believe it happens at WOT throttle is not because of pressure increase, but because of the increase of flow at the rear bowl's needle and seat. Normal driving the rear bowl float never opens, but when you nail the accelerator the flow increases at that point (needle and seat). Couple this with a poor sealing needle and seat, and/or no vent "whistle" and the inertia of car slowing or stopping quickly forces extra gas up and out of vent tube.

I removed needle and seat, cleaned it really good with carb cleaner and adjusted the rear float just below the opening. It took a lot of trial and error to get the float adjustment correct because to check it I had to drive it and open the throttle all the way. Idling in the garage and cranking open the rear butterfly helps get it close but a test drive is the only way to tell if it’s really fixed.
 
71Duster said:
Currently running an FBO "special" mechanical fuel pump on my mild 340. Twice this has happened now.

After a WOT then off and just rolling the car starts to stumble smoke and then die. Had the air cleaner off on the side of the road and the carb is pukeing fuel bowls are way over full. This has happened on 2 different carbs. Had the bowls off and no crap inside and checked the reuseable fuel filter all good there.

No gauge so no idea what fuel pressure this pump makes but its supposedly ported and polished inside etc etc.

I'm done playing with the pump at any rate. What mechanical pump to feed a mild 340 pushing maybe 350-380hp would you recomend that doesn't need a regulator.
Click to expand...

Not the pumps fault. It only fills the carb until the float rises and shuts off the incoming fuel. You have sticking or leaking floats in the carb most likely. Maybe they have leaked and are full of fuel and are too heavy now, or maybe there is crap in the carb causing it to stick. If so, it will continue to dump fuel down the carb after shut off until all the built up pressure is gone. Had this happen on my boat. I had to remove my compass and use it to beat the **** out of the carb until the float unstuck itself. Now I carry tools onboard!
 
Why not just pop in a inexpensive Air-Tex pump from Kragen,Autozone,ect ?
They are actually pretty decent pumps. If it isnt the problem, at least your not out a bunch of money. You can pop it in, in a matter of minutes. If thats not the problem you can check it off the list.

Im leaning towards carb issues, like others have said.
 
71Duster said:
...sure enough carb was wet with fuel and it had a small puddle on the intake I mopped up.

...Going to check the fuel filter and bowl again for crap but this is a new tank that was just cleaned out this winter, 4 year old braided hose...
Click to expand...

Is the 4 year old braided hose after the filter? The rubber inside will break down over time, especially with today's gas.
 
CRAIG COX said:
What about a M.P. pump? I have one new,and have never used it.
Click to expand...

There made by Carter. Who makes Carter pumps now, I'm not sure, but I do believe it would be Fed-Mougal.

pettybludart said:
I,d get a new Carter mechanical pump for the cost and less headache.I ran one on my 410sb with 850dp,car ran 10,s.This was with the factory 5/16 sender into 3/8 fuel line.(yes I was schocked)LOL.
Click to expand...

IMO, your pushingthe limit with the smaller line. While a 5/16 can actually surplythe feul needed for quick times, IMO, a 3/8 from tank to pump time is at hand.


OE Poster,, the foats must be at fault here.
 
Hey Rumble,I,ve since swapped to a sump in tank,electric fuel pump,3/8 flex line,dual filters and a regulator.Upgrades were needed as I,m about to try a dominator on top of the 410c.i.:D
 
Fuel filter had some very small debris in it cleaned it out not a whole lot in there. Pulled the bowls floats are fine and this problem has happened on 2 different carbs BTW. Bowls on the carb had a few very very fine specs of "dirt" in it.

Is it normal to have anything at all in the bowls? I can;t imagine the filter is capable of getting it all. This stuff was very fine and not even able to CSI it to say anything other then dirt from the gas sation most likely.
 
71Duster said:
Fuel filter had some very small debris in it cleaned it out not a whole lot in there. Pulled the bowls floats are fine and this problem has happened on 2 different carbs BTW. Bowls on the carb had a few very very fine specs of "dirt" in it.

Is it normal to have anything at all in the bowls? I can;t imagine the filter is capable of getting it all. This stuff was very fine and not even able to CSI it to say anything other then dirt from the gas sation most likely.
Click to expand...

Define "specs of dirt". It doesn't take much to hang a float open. You didn't answer my last question, is the 4 year old braided hose after the filter? These specs of dirt could be coming from deteriorating rubber inside the braided hose.
 
Here's a tidbit I learned from my brother several years ago... Being in field failure analisis he looked at quite a few electronic fuel injectors that were blocked open by debris.. Keep in mind these injectors were pulled from fairly new vehicles still under warranty. Some of the debris was plain ol' dirt. A large percentage of it was shards of metal. These tiny swords traveling under pressure went right through fuel filter elements.
100% of this foreign material came from the fill nozzle on the gas pump. Either sheared when the nozzle hit the filler tube or just dirt collecting on the nozzle while it hangs on the pump.
We never think about the dust and dirt that is stirred at the pump island.
Bottom line, A samll amount of debris in the fuel system cannot be prevented.
 
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