electric fuel pump *PROBLEM SOLVED*

[chargd72]

Hey guys, keeping fuel in my carb is an ongoing problem.  I have a '76 Power Wagon with a 400 that came with a crappy electric fuel pump.  Went out after a couple of months.  Then I put in a ProComp.  That piece of shit went out in 10 days.  Now I have a Holley.  It gives good pressure but it sporadic.  As I watch my fuel filter while engine is running, it fills, then gets sucked dry, fills, dry, etc.  But at least it keeps running.  But here's the part I can't figure out.  If the truck sits for a few days and I turn the pump on, my gauge reads 5-6 psi but no fuel is being pumped!  So I have to detach the fuel line from the carb, turn the pump on like I'm priming it, then reattach it.  After that, it keeps pumping.  What the hell?   My fuel pump is a non regulator pump.  Any suggestions before I pitch this thing and go back to mechanical pump?  Thanks.

[elacruze]

Hey guys, keeping fuel in my carb is an ongoing problem.  I have a '76 Power Wagon with a 400 that came with a crappy electric fuel pump.  Went out after a couple of months.  Then I put in a ProComp.  That piece of shit went out in 10 days.  Now I have a Holley.  It gives good pressure but it sporadic.  As I watch my fuel filter while engine is running, it fills, then gets sucked dry, fills, dry, etc.  But at least it keeps running.  But here's the part I can't figure out.  If the truck sits for a few days and I turn the pump on, my gauge reads 5-6 psi but no fuel is being pumped!  So I have to detach the fuel line from the carb, turn the pump on like I'm priming it, then reattach it.  After that, it keeps pumping.  What the hell?   My fuel pump is a non regulator pump.  Any suggestions before I pitch this thing and go back to mechanical pump?  Thanks.

Could your bowl vent be plugged?

[chargd72]

Nope, checked multiple times.  Just did a full rebuild on the carb.  Have a screen on the fuel inlet to catch anything nasty trying to get into my carb.  Nothing.

[chargd72]

Sorry, read that wrong.  Bowl vent, hmmm.  Haven't checked that.  How can I?

[elacruze]

Sorry, read that wrong.  Bowl vent, hmmm.  Haven't checked that.  How can I?

Don't know what sort of carb you have. If you have a Holley, remove the bowl float level plug and blow into the top vent stack. If it's clear it will pass air easily. Other carbs, can't really say.

Possible but unlikely is that your float is sunk, or partially sunk causing the inlet valve to close early.

Depending on your style of pump, you may also have a vacuum leak between the fuel tank and pump, allowing it to draw in air and cavitate the pump. the air would then show up in your filter after it purged from the pump. This is probably more likely than a plugged bowl vent, come to think of it. Because the line is higher than fuel level it will not leak while standing, only a very small amount of fuel would present on close inspection, maybe not even enough to make a drop. Inspect your fuel lines around the tank and pump for dampness or spots collecting more dust than the nearby non-jointed areas.

[chargd72]

Sorry, read that wrong.  Bowl vent, hmmm.  Haven't checked that.  How can I?

Don't know what sort of carb you have. If you have a Holley, remove the bowl float level plug and blow into the top vent stack. If it's clear it will pass air easily. Other carbs, can't really say.

Possible but unlikely is that your float is sunk, or partially sunk causing the inlet valve to close early.

Depending on your style of pump, you may also have a vacuum leak between the fuel tank and pump, allowing it to draw in air and cavitate the pump. the air would then show up in your filter after it purged from the pump. This is probably more likely than a plugged bowl vent, come to think of it. Because the line is higher than fuel level it will not leak while standing, only a very small amount of fuel would present on close inspection, maybe not even enough to make a drop. Inspect your fuel lines around the tank and pump for dampness or spots collecting more dust than the nearby non-jointed areas.

Thanks for the reply, E.  It's an Eddy 1406.  But like you said, the fuel line theory seems more like the problem.  I will go thru my lines and make sure they are all sealed up nicely. 

But even if there is air getting in the line, shouldn't that just be pumped out thru the carb?

[elacruze]

Thanks for the reply, E.  It's an Eddy 1406.  But like you said, the fuel line theory seems more like the problem.  I will go thru my lines and make sure they are all sealed up nicely. 

But even if there is air getting in the line, shouldn't that just be pumped out thru the carb?

It's possible for an air leak to allow the line to the pump to drain back into the tank, causing an airlock in the pump itself and/or poor pump priming.
Otherwise, yes any air should go through the filter/carb and out the vent. Keep in mind though, that air comes from someplace. You could even have a rusted and perforated pickup tube inside the tank, causing an air leak at more than an empty tank.

[Back N Black]

Where is your pump located?

[chargd72]

Where is your pump located?

On the frame next to the gas tank.

[Rolling_Thunder]

if the electric pump is higher than the tank it could be having problems sucking fuel up ---   of there could be a leak in the fuel line allowing it to pull air.

[chargd72]

The pump is set a coulple inches higher than the bottom of the tank.  The crappy thing is that it's not a gravity feed tank.  It has to suck fuel up from the top of the tank.  I'll check for any air leaks this weekend.  Thanks for all the help 

[elacruze]

I mounted my pump on the shock crossmember in front of the tank. It's actually above the fuel level even when the tank is completely full but I've never had any leakage, pressure, or priming issues. In fact, my Holley EFI has a 5 second default on the pre-start priming cycle which I reduced to 2.5 seconds.

[chargd72]

Thanks for the pic.  Now go hit a mud puddle or something.  It's too clean under there.   

I think I need to drop my tank and start from the pickup.  It's probably in the line, like you said.

[chargd72]

Dropped the tank and sending unit seems to be good.  Here are a couple videos if anyone has an explaination for what could be the cause.  All lines seem to be tight and leak free.  I even put on a new carb to see it that had anything to do with it.  ...same results.

Video 1:  It's hard to see the fuel filter in this video but it's slowly draining for the first part.  Then at about 25 seconds in, you can see the fuel line final spewing a bunch of gas into the filter.

http://www.youtube.com/watch?v=kjk_KorRuBE

Video 2:  My guage shows whats going on with the pressure.  Slowly goes down then gets filled before it can stall.

http://www.youtube.com/watch?v=Lp6MIl4AS-Y

The weird thing is, is that it never starves itself of enough fuel to just die.  It will stumble when I go WOT though.

[Chryco Psycho]

so when you disconnect the fuel linefrom the carb you get fuel flow out of the line & you get a steady stream right ?
it semms to me more like a float or needle & seat problem , if the needle is jammed closed for some reason the fuel pressure gauge will still read 5 PSI of fuel or air pressure . Have you removed the top of the carb ever to see if a float is sticking or the needle & seat is working or even just to check float levels as they usually are wrong after shipping .

[chargd72]

so when you disconnect the fuel linefrom the carb you get fuel flow out of the line & you get a steady stream right ?

Correct.  But a couple of things sway me away from this theory.  1)  If the needle and float were jammed, wouldn't it stop flow all of the time?  2)  I had a freshly rebuilt 600cfm carb on that I personally did and floats were moving freely.  Then I put a 750 carb on that was running just fine on the charger with a mechanical fuel pump.  Both yielded the same results.

I'm not saying it can't be what you're saying, but I'd like to eliminate all other options before tearing down another carb. 

[Chryco Psycho]

well if the carb is full it will not push more fuel so maybe a carb / choke setting is causing the start problem , & that  is why the filter looks empty ?
if the pump is pushing a steady stream of fuel with the line off I doubt the pump is the issue .
Have you had the top of the carb off at all ??
I have seen Eddys cast with missing fuel bowl walls internally , or maybe the floats are set too low , this would cause a stumble . Just looking for different ideas here , the QC is low on Eddy parts & the warranty on the mis-cast carbs was non existant

[Lunger]

is it a holley red pump , max and i mean max psi with those is 7 and that is a none running engine , they only run about 4 psi with a running engine but will bounce up and down . also is your fuel filter after the pump. it may be hindering it even more. i have allways put the filter before an electric pump. also check your filter there is a direction arrow on some of them

[chargd72]

Elacruze is the winner!  I had previously checked/replaced all fuel lines, I thought.  When I dropped the tank, there was about a 4 inch section of rubber hose coming out of the sending unit feeding back into a metal line.  There was about a half inch slit in the line so the pump was just sucking air.  I can't believe it ran as much as it did.  I also put in an Optima Red Top battery and that gave me an extra 2psi.   

Thanks for the help!