ballast resisters

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Don't condemn electric pumps because YOU had trouble with ONE. That pump could be defective, worn out, or impacted with dirt / debri

I feel the OPPOSITE about mechanical pumps. Years ago Holley sold mechanical pumps which had very high failure rates, and especially nowadays, with "alcohol fuel" they promote boiling.
 
Another aspect of ballast resistors that isn't well known is that same current vs. resistor temperature relationship helps with cold starts by supplying more ignition power right after a cold start.

Fuel runs out of the pick-up when the level is above it (BT, DT). What happens when the level is below the hose barb on the pick-up/sender? The pump has to pull it up and over to get things started. If the pump is at the front of the car it has to work a lot harder to do that than it would if located near the tank. Just as one (or more) negative events don't confirm the need, one (or more) positive events don't delete the need.

If we accept that electric pumps are not as good as pulling as a mechanical pump, then it makes the most sense to minimize the amount of pulling that the pump has to do. As a bonus, having the pump at the rear of the car causes the whole supply system down stream of it to be under pressure. This is good for stopping or reducing vapor lock. Doesn't take much of a vacuum to significantly reduce the boiling temperature of gasoline.
 
Didn't condemn them , I just decided to go the cheaper way for now , see how it goes , and maybe do it right down the road with the right pump , location , and relay.
 
Right on on Desy, sounds like that pump took a crap, the mechanical will be fine
for now. Mechanical pumps don't prime any better, anyone my age who lived on
carbs and mech. pumps have run out of fuel a couple of times, and if you put a
splash in the tank your odds weren't good. All pumps push fine but pull
marginally if solid fuel isn't present, that's why NAPCAR cars mandated to run
mechanically operated pumps, were using a drive cable from the eng. to a
remotely mounted pump in the rear.
Usually at the shop, someone would crank the eng. for me while i applied a
bit of compressed air to the tank, and bang away it went. Putting a filter in
front of the pump can prevent some problems as well, something i recommend.
Cheers!!:coffee2:
 
Filter between the tank and the pump is an additional restriction. Not recommended, makes the pump's job even harder.
 
Is there any danger in blowing some air back through the line to the tank?
 
If the tank pickup still has the filter sock it may blow it off the end. If the tank and pickup still look like original and untouched it may have rotted away by now.
 
Yes you could blow the pick-up screen rite off even if its not bad, if you suspect
it is clogged you should just drop the tank and visually inspect it and the tank
for rust and dirt. Both a high probability in an older car, hell even some not so
older cars for that matter. I have also installed filters prior to pumps numerous
times w/ zero problems, fine rust and dirt will do more harm to the pumps
efficiency than the filter.
I doubt your slanty is going to be taxing that pumps output,lol, I ran a
stock mech. pump on my swinger w/ a built six that got raced and beat on
regularly. No fuel problems and 168HP to the wheels, you'll be fine.:)
If the pump failed the output test from the tank,did you try simply running
a length of hose FROM the 5Gal. can to the pump inlet rite away? Simply
circulating fuel thru should expose a starvation problem if it pumps fine all
of a sudden w/ that arrangement.
good luck:coffee2:
 
I've seen it done too, filter in front of the pump. I just don't suggest or recommend it. All of the domestic OEM's used the sock to filter out chunks too big for the pump to handle and put the filter after the pump. They had good reason to do it this way.

The issue isn't taxing the pump's output. The issue is that a filter in front of the pump (btwn the tank and the pump) increases the restriction making the pump work harder at it's worst action - sucking the fuel out of the tank. If that filter happens to be placed near the tank instead of up front near the pump then it also causes the whole supply line to be under a greater vacuum, further and sometimes dramatically increasing any possibility of vapor lock.

If the reason for wanting/needing to blow air thru the line is suspected plugged lines, then you certainly don't want that carp going into the tank anyway. Just disconnect the supply line at the tank and blow to your heart's content.

If the reason for wanting to blow thru the line is that you suspect that the hoses have embolisms that have turned into flaps obstructing fuel flow then replace the hoses with "emissions barrier" hose because any older or lower end hose probably has done this by now anyway.

If the reason for wanting to blow thru the lines is a suspected plugged sock then the pick-up really should come out and it wouldn't hurt to clean the fuel tank while you're at it. If the sock is plugged, blowing thru the lines will only be a temporary fix at best.
 
Well, if restriction is a problem, I'm sure Desy will figure it out.As far as pre-filtering
the pump,
a)vacuum is what creates flow from the tank to the pump,something it has a hard
time developing w/"acceptable" chunks of debris trapped in the valving
b)properly placed pumps are low in the vehicle,so losing their prime once flow
is established usually is the result of one thing-running your car out of fuel,
solution?,don't run your friggin car out of fuel!!
c)vapor locking is the result of too much heat in the pump body& line running
over the engine,it matters not what's going on before the pump,as long as it
is that hot any fuel that manages to enter it just boils and perpetuates the
the problem.Solution? cool the pump,better yet protect it and the metal line
from heat B4 it's a problem.W/o an exh. man. hovering above/behind it,
my slanty NEVER vapor locked,even driving to the track for close to 3 hrs.
and waiting in line.
d)all toyota tks w/carbed 22R engs. had the filter at the tank,& the pump on
the cyl.head run off the cam.Road was just littered w/them summertime-
NOT!!
E)500ci caddy,440satellite360rwhp,SB&225darts,455'64olds405rwhp,383Mbody
w/4.89's&nitrous4spd445rwhp.............
OK I'm done:D
 
The one thing about a pre-pump filter is that it MUST be designed for the job. Low restriction and plenty of flow. "Just like" anything, HVAC, turbos, whatever it might be, pressure / flow restrictions at the "low side" of a system are much more hurtful than on the "high pressure" side.
 
sigh.....
Vapor lock is the fuel turning from liquid to vapor. It's boiling! Just as the radiator's pressure cap increases the coolant's boiling point by pressurizing it, a vacuum reduces the boiling point. This is true for any liquid. The relationship between pressure and boiling temperature is unique to every fluid, unique enough that a fluid can be identified by this trait.

I own one of those 22R trucks, have put ~125K on it. Works great so long as you never allow even one bubble in the fuel system. If you do, you're done. Out of gas with a full tank.
 
Those damn bubbles!!! Yes, and that fail is mainly due to the higher than tank
position of the pump,which a number of foreign cars used w/OHC.
 
Killer6 said:
vapor locking is the result of too much heat in the pump body& line running
over the engine,it matters not what's going on before the pump,as long as it
is that hot any fuel that manages to enter it just boils and perpetuates the
the problem.Solution? cool the pump,better yet protect it and the metal line
from heat B4 it's a problem.W/o an exh. man. hovering above/behind it,
my slanty NEVER vapor locked,even driving to the track for close to 3 hrs.
and waiting in line.
Click to expand...

Sorry, not correct. Heat AND pressure is the correct answer. You do something which lowers the pressure, and you make a liquid easier to boil. ANY liquid. This is one huge reason why modern EFI systems are much much less prone to vapor lock / boiling. It's because the fuel system is under MUCH greater pressure, just exactly like a pressure cap on a radiator

Heat of course IS involved. But if you restrict the inlet to a pump enough, the pressure drop WILL cause vapor lock due to a drop in pressure. This problem might be less on a cold winter day, worse on a 90 degree summer day, and much worse if hot exhaust is "idling around" "back there" but all these factors change the point at which vapor lock happens
 
If you lower the pressure far enough you can make almost any liquid boil at room temperature.
 
ntsqd said:
If you lower the pressure far enough you can make almost any liquid boil at room temperature.
Click to expand...

Exactly which is why you pull HVAC /R systems down to a very very low pressure, sometimes called "high vacuum." This causes (hopefully) anything in the sytem to be boiled off and pushed through the pump and out.
 
Lmao!!, all this under the "ballast resistor" heading,must have a few scratching their
heads!! First of all, you can ease up on the mister science tag team,I am acutely
aware of pressure effects on all fluids,incl. the applied btu "bombs" used to measure
and assign Reid vapor press.,the ASTM 10% distillation method to measure volatility
EAD method etc., not for one second am i stating restrictions are good or harmless.
The above listed vehicles are real world, some mech.,some electric pumps,
some have no pickup sock/screen at all, and the filter is all that is protecting the
pump.67 had it right, if it is chosen/designed correctly for the job,it is NO problem.
Apparently,someone forgot why this thread was started,to help Desy get his
ride on the go.Pretty much unanimous on don't add anything to the Ign.2 circuit
other than a relay.I have seen many old PU socks fail after many rounds of old
fuel,rust, and god knows what else.My late uncles 500ci coupe deville had only
23K on it,stayed in an attached garage,and semi=heated. unfortunately, it was
not driven enuf,nor kept full of fuel.Condensation rusted the entire interior of the
tank,and the old fuel attacked the plastic the sock was made of.When the cloud
of rust plugged a portion of it it split under the vacuum and flushed the pump w/
junk,and quickly packed the roachmaster peanut filter. A std. inline filter will
protect desy's pump, and not create one lick of trouble in his case,tho' he may
have to change it often if the above case is his as well until repairs are done.
 
so I finaley got time to switch out the electric pump , put a mechanical back in , tried to run the line to the carbs as close to the factory set up as I could , covered most of the new steel line with 1/2 '" heater hose , replaced the fuel filter , replaced the rubber hose from tank to steel , put 15 gals of premium shell gas in the tank , and drove for about 10 miles. It didn't die , but the fuel in the filter was almost gone , shut her down , now when I checked it the next morning , fuel filter was full ? You guys think this is vapor lock ?
 

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Well, whatever you do,I'd get that plastic filter away from the header wrapped or not.
The lack of liquid fuel in there is a problem,I've seen lots of cars run with those
filters showing partial filling,usually a result of the orientation,trapping air/vapor in
the top "corner".Completely empty after a drive is not OK for sure.Did you make any
determination on the condition of your tank/pick-up,and what was that?
 
Mmmmm using heater hose for insulation is not a good idea. It may slow down the heat soaking into the line, but it will also trap heat better in the line once it gets hot. And if it is black heater hose, it will do a great job of absorbing radiant heat off of the engine! Get rid of that and use AL foil at least and better yet, aluminized reflective wrap made for this purpose.

Can't say it is vapor lock per se... and can't I've ever observed the filter to be filled after empty hot....very interesting. Was the car parked level, or downhill, or? I would be concerned about a restricted line from the tank or the in-tank screen if you have not pulled it to inspect.
 
I didn't drop the tank , but I was able to fill a quart container in 30 seconds , before I took the electric pump off. also filled a 5 gal can fast ( I didn't time it ) the car was parked in my garage it has the normal pitch an inch or two to let water run out the door, so if anything the car was leaning towards the tank. I have done this several times seeing the fuel very low or almost empty , then full the next morning , I wasn't sure if it was coming back out of the carbs , or vapor turning back to liquid. The heater hose over the fuel line was from someone on this site , so I tried it. This problem started this thread with the electric pump pulling power strait off the ballast , at that point the car was running out of gas and stalling , the fuel line was all rubber , and didn't run over the header , just over the heater hoses , and the valve cover. so when I put the mechanical pump in I ran the metal from the pump to the carbs , the route the factory did it , and it didn't run out of gas and stall in 10 miles , so it did improve , but it was a cooler day?
 
!st question,was the engine still running when you snapped that pic?If so your pump
is starving,if it was heat related and running there would be some fuel foam in the
filter.If you shut it down and the fuel disappears,that can happen with the filter up
high,but it shouldn't take too long(5-6 secs.)to refill.Heat soak after shut down
can cause vapor to force liquid fuel back down towards the pump if the carb float
is up,and the pressure has nowhere to vent.That is the primary reason for the
three line fuel filters w/ a return to the tank being introduced.
One thing I neglected to suggest was to check the tank vent line to be sure it is
clear.Disconnect it at the filler tube(You may have to whittle the old hose off tho')
and blow compressed air(w/the cap off)thru both the short tube into the neck and
down the long convoluted tube.It should be free to blow thru both, tho' the long one
will sound restricted comparatively,bugs have a way of plugging those up.We have
had 4-5yr. old cars that tiny spiders webbed up the vent lines and set the MIL on.
Lastly I'll leave you w/this.I had a cust's. AMC spirit come in w/exactly the same
issue, tho' sitting still it'd run 1/2hr. no prob.,but 3mi. of driving you could feel the
surge comin then dead.Wait 5-10 crank and it'd restart repeat like clockwork.The
cause was fine rust in the tank which would only stir up and cover the sock driving.
It'd drift off & settle once the eng quit,then euff flow'd be there to do it again.
 
Agreed 100% on the above with the sock getting plugged up as you drive. Some testing is good, but dropping the tank with this issue is almost 100% required. The junk that can get in these old tanks is large, and the problem with that are VERY common. You just gotta get under there and do it, regardless of the difficulty.

BTW, the pumping of fuel from the pump with it into a can is just one test of the pump and does not completely test it. The remaining test to be done is to tee a fuel pressure gauge in to the line to the carb and run the pump and see if you get around 4-5 psi pressure. Then, cut it off, and see if the pressure holds for a long time....many, many minutes. This last test checks the pump's output check valve to see if it is properly closing. (There are check valves in the pump at both input and output and both have to close properly in every pump cycle.)

Also, with the mechanical pump, pull off the pump and make sure that the pump lever is aligned right; if it is excessively loose, then it won't pump right. You should be able to rotate the engine 'til the pump cam is pointed down and to the passenger side, and at that point, the pump ought to be a bit hard to install as you would have to move the lever to get it in place.

But, fuel pump issues would not explain why the same problem exists with both electric and mechanical pumps. So the plugged line is still the primary suspect.

Your getting a problem with fuel for sure with that filter not being anywhere near full. I don't like the clear filters but in this case, it has a value in troubleshooting.

And yes on the heater hose over the line.... I've commented on the problems with that approach before.
 
Killer6 said:
!st question,was the engine still running when you snapped that pic?If so your pump
is starving,if it was heat related and running there would be some fuel foam in the
filter.If you shut it down and the fuel disappears,that can happen with the filter up
high,but it shouldn't take too long(5-6 secs.)to refill.Heat soak after shut down
can cause vapor to force liquid fuel back down towards the pump if the carb float
is up,and the pressure has nowhere to vent.That is the primary reason for the
three line fuel filters w/ a return to the tank being introduced.
One thing I neglected to suggest was to check the tank vent line to be sure it is
clear.Disconnect it at the filler tube(You may have to whittle the old hose off tho')
and blow compressed air(w/the cap off)thru both the short tube into the neck and
down the long convoluted tube.It should be free to blow thru both, tho' the long one
will sound restricted comparatively,bugs have a way of plugging those up.We have
had 4-5yr. old cars that tiny spiders webbed up the vent lines and set the MIL on.
Lastly I'll leave you w/this.I had a cust's. AMC spirit come in w/exactly the same
issue, tho' sitting still it'd run 1/2hr. no prob.,but 3mi. of driving you could feel the
surge comin then dead.Wait 5-10 crank and it'd restart repeat like clockwork.The
cause was fine rust in the tank which would only stir up and cover the sock driving.
It'd drift off & settle once the eng quit,then euff flow'd be there to do it again.
Click to expand...

yes I could take a picture like this with the engine running , on any given day. yesterday I started out with the filter full , drove about 2 miles , just to check it , pulled up in the drive , filter was close to empty , and let it run another 10 minutes , just little spirts of gas coming into the filter took the gas cap off , no change. shut it down. waited 10 minutes , started it up, no change. waited 1 hour , started it up , filter filled up.
 
nm9stheham said:
Agreed 100% on the above with the sock getting plugged up as you drive. Some testing is good, but dropping the tank with this issue is almost 100% required. The junk that can get in these old tanks is large, and the problem with that are VERY common. You just gotta get under there and do it, regardless of the difficulty.

BTW, the pumping of fuel from the pump with it into a can is just one test of the pump and does not completely test it. The remaining test to be done is to tee a fuel pressure gauge in to the line to the carb and run the pump and see if you get around 4-5 psi pressure. Then, cut it off, and see if the pressure holds for a long time....many, many minutes. This last test checks the pump's output check valve to see if it is properly closing. (There are check valves in the pump at both input and output and both have to close properly in every pump cycle.)

Also, with the mechanical pump, pull off the pump and make sure that the pump lever is aligned right; if it is excessively loose, then it won't pump right. You should be able to rotate the engine 'til the pump cam is pointed down and to the passenger side, and at that point, the pump ought to be a bit hard to install as you would have to move the lever to get it in place.

But, fuel pump issues would not explain why the same problem exists with both electric and mechanical pumps. So the plugged line is still the primary suspect.

Your getting a problem with fuel for sure with that filter not being anywhere near full. I don't like the clear filters but in this case, it has a value in troubleshooting.

And yes on the heater hose over the line.... I've commented on the problems with that approach before.
Click to expand...

Ya , same problem , both pumps , although some improvement I haven't ran it out of gas yet , and have gone further then when it ran out with the electric pump , I am thinking that previous owner was having same issue , and tried the electric pump to fix it. I am going to cut open the old filter I replaced to check for any sign of junk in it , the gas was very clear when I pumped it in the jar, and I am going to pick up some dei cool tube , or is there a better one ? I don't have a pressure gauge , but I guess I borrow one before dropping the tank.
 
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