I have a 140 gph electric pump such as this:
http://www.ebay.com/itm/High-Flow-Pe...5UR99~&vxp=mtr
Cheap $50 pump, probably from China. I have it in the trunk floor. I drilled through the trunk floor plastic plugs and got the fuel lines in and out, carefully shielded from the left exhaust pipe. I also have a voltage regulator.


In the process of tuning the car since last April, this set up has been giving me all the fuel pressure I needed. I had a good 7 psi at WOT testing. Recently, in a little local road trip, I noticed the pressure going down to almost nothing at long red lights, restoring quickly as the car moved, but some hesitations aftetwards, even with good fuel pressure, presumably due to vapor in the lines. Then, further testing shows that at WOT I lose fuel pressure. I thought may be the warm weather with winter gas (pump does get warm, even though away from engine heat), but drove the car with 40 F (that's cold around here) and the gasoline cold, and still the same symptoms.


I will raise the car and check the fuel lines under the car again, but its doubtful that anything is wrong there. May be some debris is in the pump. I will open the flange and check. Any other guesses? Anybody else has experience with these style pumps?


Thanks

 

What kind of car, engine "we" workin on?

Are you saying you have the pump IN THE TRUNK? Get it out of there

So far as that particular pump, "I know nothing."

People have had good luck with the Walbro pumps

I'm a HUGE believer in vapor return systems, just like the old 440/ hemi cars had. You can easily build one using a Wix 33040 /33041 filter (or equivalent) which has a return orifice port.

Too low at WOT tells me either you have a serious restriction in the system, plugged filter, whatever, or the pump has a big problem

DO NOT mount fuel components in the trunk.

 

68 Imperial, mildly souped up 440 with cam and head work. As I said, I had good pressure for a about 300-400 miles worth of tuning, and all of a sudden I am getting problems.


There is no convinient location on the rear subframe to install, so it goes in the trunk, at least for now.


Fuel return is great in principle, but you have to drill a new hole to the gas tank to bring it back. The pump system I had was working well for a while, apparetnly these pumps are designed to pump against a dead end.


The question is, why did the pump all of a sudden is acting up ? ...

 

I agree.... Sounds to me like the set up is out of wack, and the use of cheep parts has come back to bit you...

 

Are you suggesting that I should buy a more expensive pump?
The local speed shop wanted $200 for their pumps.


I do have a spare identical pump, and I was planning to replace it and see what happens.

 

I think you have the rite conclusion.... Keep us posted...

 

Problem is .. I am cheap, and do not like expensive solutions!


A bit before I noticed the problem I had some problems with the alternator. The output cable was not making contact and was not charging. I moved the cable by hand with engine running, and saw a bunch of sparks on the alternator, apparently charging a bunch. May be this voltage surge damaged the pump.


I replaced that alternator at that time (consistent with my cheap nature, it was lifetime warranty).


Will tyry putting the spare pump on over the weakend (identical). Will also go under the car and inspect the hoses.

 

I tried to start the car yesterday and drive it on the ramps to see what's happending underneath. The fuel pump gave no pressure. Replaced the pump with the spare, same.


I raised the car with the jack, went under there, removed the hose from the tank. The pump could suck fuel from a little cup under the car.


So, the sending unit in the tank must be blocked. I can either remove the sending unit and clean the pipe, or push a wire through the pipe and push the restriction in the tank. If the second, I am wondering what are the odds of the junk to block the line again. The sock is long gone.

 

A bit warmer today, so I worked on the car.


Took the hose off the tank and drove a wire in there until it got wet with gasoline. Pulled it out, connected the pump. Still zero pressure.


I had a can of gas, took the hose off the tank exit and dipped it in the can. I was surprised, still no pressure. I had done the same test last time, but sucking from a cup, and it suched the fuel up (which came back to the cup when the pump was off).


Then I took the hose going into the regulator, The pump was pumping fine, filled up an empty oil bottle quickly. That must be the problem. Took the regulator apart, could not see anything. Reassembled it. I got fuel pressure, after I tapped it, but still the pressure goes down under load. It did not even need WOT to see the pressure going down, just accelerating up the hill.


It must be the regulator, but I can't see what could be wrong with it. The ball gets stuck? Anybody has seen this before on fuel pressure regulators?

 

Check the regulator in the pump....
The pump might have flow.... But may not have Pressure....

Keep us posted....

 

Sorry ...no "trick" ideas. Do what you are doing......however have you actually MEASURED? pressure, suction, volume? And voltage to the pump?



Blow out the main supply tube? Clean (if possible) the pump screen? Collapsing suction hose?

And I don't care what, you need to get that thing out of the trunk. Mine, on the Dart, is mounted below the trunk sort of above and behind the rear axle.

 

Thanks all.


Not sure if this pump has a built in regulator. But prior to figuring out the problem with the regulator, I had installed my spare identical pump, with no difference.


I have a pressure gage in the dash. I can read fuel pressure while driving. I can easily measure voltage in the pump, but it has to be identical to the main voltage. I picked up power from the starter relay, with a fairly thick wire to the back of the car. And the alternator is charging. It is hard to beileve there is any voltage drop.


The suction hose is a regular 3/8 fuel hose.


As said before, this same setup had worked fine for the past 300-400 miles, giving me constant fuel pressure throughout all the tuning driving all the way to 5000+ rpm WOT. I would hold 2nd gear to a true 103 mph reaching these speeds fairly rapidly ... And now, it has trouble holding fuel pressure while going up a hill accelerating with 6-7 inches of vacuum under 2000 rpm.


It appears that the external regulator started acting up. In order to confirm that with 100% certainty, I can bypass it completely and drive the car. It appears that the carburetor can handle at least 10 psi of pressure. I am not sure how much pressure this pump will give, but if the engine floods I can turn it off, drive with the fuel still in the bowls, and turn it on again under lead and on and see what happens to the fuel pressure. If the fuel pressure still struggles under load, then that may not be my problem.


Another easier test is to try first is just raise the regulator pressure. Will play with the car some more today, we have nice weather.

 

The Pressure information is in the E-BAY info you posted...And yes the pump is regulated.

 

Thanks. I guess it has to be, otherwise the pressure would keep on going up.


I did a quick test with increased pressure to 9 psi on the external regulator. I could climb the hills with mild acceleration without pressure loss. But at WOT, especially after a long idle (regulator closed), the pressure loss returned. At one instance, it did not recover until the engine died. I opened the trunk (wish the original owner had ordered the remote trunk release), tapped on the regulator with a wrench, and pressure returned.

 

More updates. It turns out it was the fuel pump. Strange as it seems. The fuel pump would at times sort of work, and then totally crap out. The spare fuel pump never worked at all. The "good" fuel pump stopped working even with the regulator by passed.


I replaced the pump with one of these Carter pumps that have been highly recommended. According to the directions of the pump, it should be installed no more than 24 inches above the top of the tank. I have it touching the top of the tank, so I am well within its specs (they also recommend a fuel filter upstream, which will tak further its pumping ability, but I don't have one yet). Some hot rodder was telling me he has had it in engines of more than 500 hp, and never seen one fail. I installed that in, and while I finally got reliable fuel pressure at normal conditions (5.75 psi without the regulator), at WOT it cannot keep up.


That prior hot rodder suggested that may be the exhaust venting is stuck and try again with gas tank cup removed. Have not tried that yet, but I doubt that is it. Another possibility is that the sending unit inside the tank may have a small hole or crack in the steel tube picking up fuel, and may be sucking air. This has low likelihood, as there are about 18 gallons (in the 24 gallon) tank, but I fill it up and try again. I also tried to suck from the fuel line that the pump sucks, and it felt like fuel was coming up easily.


Any other thoughts of what could be going wrong?

 

Demitri

Here is what my pump manufacturer recommends!

To ensure proper fuel pump performance and longevity, mount pump level with
or lower than the bottom, and as close to the tank, as possible.


I would mount the pump level to, or below, and as near to the tank pickup as possible

I would never mount an electric pump above the tank!

5.75 psi is less than desireable/very minimal for it to keep up at WOT.

 

Yes, I saw that note too, and that could be something worth trying, but I am trying to postpone this as it is not particularly convenient and has its own long term drawbacks too. The best position I can find is in front of the front leaf spring mount, so its not so close, and is hard to keep the hoses well protected from suspension components and exhaust. Behind the rear wheel inside the fender is another area, but it will get splashed directly from the wheel, not to mention possible road debris. The area around the differential needs to stay clear for suspension movements.


But they also stated in the instructions, " never above 24 inches above the tank" which appears to be conflicting. It seems that for full performance potential of the pump, indeed the pump should be low. But as long as it is within 24 inches above the tank, even if I have less than 100% performance, it should still be capable of working. If this pump can supply fuel for a 600 hp engine, well, even at 50% capacity it should still supply enough fuel for my WOT 440 at 3000 rpm (even at a 1st gear blast of not much more than 3000 I saw the pressure dropping to 3 psi). And remember, I have no up stream filter yet, which will certainly labor the suction side of the pump at high flow rates. So, at this point, I really doubt it is the elevation that causes the problems.


So, there must be something else restricting the performance of this pump, and the prior one for that matter (also electric and installed in the same general area). And whatever happened is something that happened suddenly, i.e., things worked well for the past 300 miles with full power all the way to 5000 rpm and never an issue with fuel pressure. I will check the voltage that the pump gets while running and see if there is any voltage drop compared to battery voltage. I will check what happens with the fuel cup off. I could remove the sending unit and inspect that (not fun). Any other thoughts?

 

You just have to go through from one end to the other and check things out. As old as these girls are 'anything' can happen

1...Make sure the tank is venting. Plugged vent, wrong cap, whatever This is easy to see if you simply check the pump with the cap off

2....Plugged filter sock on the pickup tube, or in some tanks, the sock/ filter can get loose and "suck up" against the pickup tube. Sender / pickup assemblies are not all that difficult to remove, but I would round up a sender gasket at the very least

3...Soft, collapsing sender --to fuel line (suction) in this case sender to pump.

4...Plugged tubing anywhere, the sender in and out of the pump, plugged filter in the pump or external. Plugged tubing from front to rear.

Review the fuel section in the service manuals. Regardless of mechanical / electric, all pumps should meet the minimums in the "specs" in the shop manual. There are procedures in there to check vacuum, pressure, and volume

You can download several years's manuals for free at MyMopar.

 

Well, I took the sending unit out. Did not see any obvious obstructions. I could blow through it. I had a spare one, it may have been flowing a bit easier, but it may have been my imagination. Installed that. I noticed that one of the hoses on the inlet side of the pup was a bit kinked. I could blow through it, but who knows, may be under suction it collapsed. I replaced that.


Upon starting the pump, it only gave 3 psi with not running engine. Upon starting the car, and cycling the switch (so that fuel bowl empties by running engine, then pump refills with high flow rate) got the pressure to go back to 5.5 psi. Did not test drive the car to see what happens under load ...

 

Test drove the car. No improvement, with fuel cap off or on. Again, even a part load acceleration was enough to get the fuel pressure down. On a brief WOT with speeds never getting above 3500 rpm, the fuel pressure went to zero and never recovered. I got the car going again by reinstalling the old mechanical pump (which by itself also cannot give sufficient pressure). With the mechanical on, the electric pump started working again.




Now, I am hoping that the two pups together (carter on the pump, mechanical on the front) will be able to sustain fuel pressures at all conditions. Will see.

 

I think I have a theory that stands as to what happened.

I think when I filled the tank back in December, the fuel lever reached areas of the tank that had rust or other debris, which is now mixed in the gas. The electric fuel pumps work based on tight clearance between two geared (not exactly the shape of gears, according to what I have been told) circular parts, like an oil pump. The crud went in there and opened up the tolerances. This may or may not be permanent.

I have now connected the mechanical pump, which is very weak by itself, but it helps prime the electric one (either the assumed cheap made in China, or the Carter one). With the two combined, the car does not die in traffic. But at WOT, I still run out of fuel.

One way is to put a filter upstream the electric pump, at the expense of some restriction in the suction sise. May be that will keep the crud out, and may be the pump will eventually clear up. Another is to put both electric pumps in parallel (the new Carter, and the old Chinese) boosting the weak mechanical. A third is to buy a mechanical high volume pump, but that requires more $$. Another is to just wait it out, and may be if I don't fill the tank all the way to the top. the crap will go away.

I may try both pumps tomorrow in parallel. The more I drive the car, the more I get this contaminated gas out.

 

electric pumps push fuel and are no good at pulling it up out of the tank. keep it simple use a mechanical pump

 

Definitely an advantage to keeping it simple. The only hesitation is I have to spend more money, while I have already purchased these pumps.

I attempted to test the car with two electric pumps in parallel. I did not get to the WOT part. The car was pining like crazy at part load. From 1300 to 2000 rpm, anything less than 8 " of vacuum, I had crazy pinging. I did not have that yesterday in the other test drive. The only explanation is that the fuel passages are restricted, and the car is much leaner than before. I tried revving the car and choking it, no difference. I think I may have to take the carb cover off and spray the passages with carb cleaner.

Has this ever happened to anybody with an Ederblock AFB carb?

 

Just food for thought... You might back flush the system and between the carb and the tank... Install a Wix 3/8 or 5/16 fuel filter to catch the stuff before it gets to the pump. You know.. Between the tank and the pump...
The carb you just will have to open and flush out...

 

Yeah, removing the carburetor top off and spraying carburetor cleaner inside the jets (essentially acetone) is not a big deal.

So, you think too that the pinging is caused by restrictions inside the carburetor passages?

 

Not sure on the pinging at the moment.. That will have to discuss further ata later time...
Just addressing the rust interning the fuel system at the moment... Without dropping the tank to have it cleaned and seal coated....

 

Well, let's try the carb cleaner and see what we learn from that. I suspect that the dirt in the carburetor is making the car very lean. Hence pinging. I also suspected that may be one of the metering rods gets stuck, but they seemed free to move.

 

I have a new possible explanation on the pinging. My distributor (unknown source) may be sticking again and give me more advance at low speeds. I tried to feel the rotor, but except for a tiny amount at the end, it feels reasonably stiff. Better than my old one. But I am not sure. If the carb cleaner does not do it, I will retard some more. Id did not want to do that earlier, I thought (and still hope) that I had the timing right.

 

Back on my pinging.


I got a suggestion that it may be piston knock. I ruled this out. I tested the car cold, and at first vacuum as low as 5 inches there was no knock, and as I was going up the steep hill next to my house, you could start hearing it. Its definitely spark knock. Once warm, anything less than 8 you hear it.


I took the carb top off and sprayed carb cleaner through the jets. I do not know if that took away the crap. None of these circuits was completely clogged, otherwise the car would not go (I could not feel much difference in performance). But no difference. I retarding the timing some, no difference. I rerouted plugwire 7 behind the engine, no difference. I guess I can retard more until it stops, but that will defeat the purpose of the engine ...


Any thoughts? Other than a cogged carburetor, why would this start suddenly?

 

Hope you all the crud out of the fuel system and now have a filter back at the fuel tank to stop it from moving forward.....?????


As for the Pinging..... I think the old girl needs a little octane booster to help out with that problem... Just my thoughts...