fuel tank to fuel pump elevation

[noslin]

im wondering if we are having fuel draw issues on our rig.   yesterday on the stand it started no problem three times.  we filled it to the top in the tank and proceeded to start three times using most of the 5 gallons in the tank without issue.  at the track we started it on the stands no problem and im pretty sure i filled it up to say 1/2" of full.  made a test pass and it started no problems in the staging lanes like it should.

we went up for the second pass and it just would not prime/start.  i dont know how full the tank was, im guessing within an 1" of full.   the pump was just rebuilt by Enderle, its an 1100.  it has six startups on it.   the second you take the fuel bottle away it dies.  the last time trying to start he just squeezed the bottle to keep running and it should of primed but it didnt.  so we are wondering if there is a problem with height of tank and pump elevation.

all feds have the tanks way up front.  I just put solid 1.25 alum tubing straight from tank to the pump thinking the braided i had on there was sucking air.  we just stuck on the new pump inlet fitting on it, new o-ring etc and made sure it was seated correctly.   

its just frustrating to us seeing how it ran fine one time and then next time its a little bitch and wont run.  its a simple system but we are wondering if the fuel level and pump elevation might be part of the problem.  what perplexes me is how can you start it three times without refilling the tank and it starts perfect each time with varied fuel levels and then when its time to go play it decides not to.  he was pouring the fuel in to keep running and long enough to prime and second he pulled the fuel away it dies so we know the pump isnt priming as the feed line up to the BV is dry.   I checked the pump drive shaft and its just fine.

Lets talk about fuel level and pump elevation.  sitting on the ground the  tank is 11" to the top.  so full would be about 10.5".    the bottom of the pump inlet fitting is 10", the barb is 1", the bottom of the pump is 13.5", the center of the pump is about 14.5 (guess).

Do we need to make a taller tank?

my buddy was doing some research and he noticed a lot of the older feds the motors sat lower in the frame (guessing) so the tanks were tall enough to prime etc no issue.  whats the history on evolution to the new modern chassis design to the older ones if there is one?  I know each chassis is custom fabricated and no industry standard.  is there a target crank shaft height guys shoot for or does that matter.

Thank you
Dean

[Rat]

I hope someone has a solution as we are having the same issues. We have discussed but not yet tried these idea's - a check valve, primer pump and raising the tank. Look forward to hearing the feedback.

[Curly1]

The pump can draw fuel up some but you do want to make it easy as possible.  I think it is always difficult to make a MFI system start nice and clean on alcohol. They are touchy, too much alcohol it floods and does not want to start. Same if there is not enough fuel. Mechanical injection dumps a lot of Fuel at low RPM because it does not have pump shot. And alcohol is harder to start in colder weather. Mine runs better when motor is hot but is harder to start. So you are trying to get the right fuel mixture to get it started and run.

[hemidakota]

Dean take the outlet line to barrel valve off at fuel shut off and crank engine to see if pump is working. Have seen a couple good pumps just stop working. Easy check before any changes.

[noslin]

The pump can draw fuel up some but you do want to make it easy as possible.  I think it is always difficult to make a MFI system start nice and clean on alcohol. They are touchy, too much alcohol it floods and does not want to start. Same if there is not enough fuel. Mechanical injection dumps a lot of Fuel at low RPM because it does not have pump shot. And alcohol is harder to start in colder weather. Mine runs better when motor is hot but is harder to start. So you are trying to get the right fuel mixture to get it started and run.

where learning that too.  was using gas, then went to meth and a mixture of gas/meth, now back to gas. 

Dean take the outlet line to barrel valve off at fuel shut off and crank engine to see if pump is working. Have seen a couple good pumps just stop working. Easy check before any changes.

weve ran the pump couple times with just a drill and tried that.  it actually pumped fuel.  this pump is basically brand new. enderle just rebuilt it and put new cover plate on it.  just counted and we have one pass and seven starts on it.  the drive is ok too.

we will get the fed out of trailer and get solid numbers on elevations.  i think the differential is about an 1".

[jeff/21]

we had the fuel shut off right after the pump to keep the lines full , belt driven pump, had to raise the frt end for cold starts after warmed started well, we always used gas in the squirt bottles don't know if it's the right but worked for us- 406 na, 406 blown, and 500 blown(had a cam driven pump)

[dreracecar]

First thing to check is the pump, I don't care if you say its fresh. Pull the pump, and spin the hex drive, if it spins freely like a top with just your fingers , somehow you killed it by not having enough "free-play" and you drove the impeller into the front cover and opened up the clearance and its not making enough low pressure to pull fuel or even push fuel for idle, the pump is just windmilling. If you are running A/F with a 6.5 gal pump makes matters even worse due to the small pump.  I had the same issue and never thought about the pump because it just came back from enderle, the motor was a fresh build and did not check the freeplay. If it takes a wrench to spin the pump, then the problem is elsewhere , but you know its not the pump

[jeff/21]

dreracecar good answer seen it done with all kinds of pumps never thought of that.

[noslin]

First thing to check is the pump, I don't care if you say its fresh. Pull the pump, and spin the hex drive, if it spins freely like a top with just your fingers , somehow you killed it by not having enough "free-play" and you drove the impeller into the front cover and opened up the clearance and its not making enough low pressure to pull fuel or even push fuel for idle, the pump is just windmilling. If you are running A/F with a 6.5 gal pump makes matters even worse due to the small pump.  I had the same issue and never thought about the pump because it just came back from enderle, the motor was a fresh build and did not check the freeplay. If it takes a wrench to spin the pump, then the problem is elsewhere , but you know its not the pump

Thank you for your input.  when i disconnected the pump and moved it to check the rod then went to put it back on i had to rotate the pump shaft which i did with my fingers with ease.. so thats it then.  amazing it would go that quick. we set the free play up and thought we had it dialed but must be off.

we think the pump needs to be lower or taller tank or combination of both.  right now with full tank, the fuel level is at 11" above ground, the pump is 16" to the center.i could build another tank and probably get another 1.75-2" out of it putting fuel level at 13" +/- but the fuel should be at the pump from what i understand. 

From what i have heard, its not a good idea to run the pump dry for very long or it will go bad in a heart beat. Do guys drop oil down in the pump between starts?

what would be minimum acceptable differential between fuel level and pump center line, bottom or ?  getting kind of spendy and frustrating dealing with this.

what are options to lower the pump?   I see there is a mag/pump offset drive.  could use this, rotate 90 deg and drop pump down a few inches.   could use belt drive (guess).  would a spur gear pump be better and take more abuse?

I never paid much attention to tanks and pump elevations etc while checking out other feds.

thank you
dean

[dreracecar]

At this point, tank level and pump hight is not a player, the pump will draw the fuel.  I tend to have the front/bottom of the tank a little higher than the rear so that gravity helps feed the outlet.  Fill the tank full with water and the outlet capped, then pull the cap to see the fuel stream exit. should be a nice solid stream, surges and dribbles means that there is a problem with the vent. Try routing the fuel from shut-off back into the inlet side of the pump as when you shut it off the fuel just circulates and the pump doesn't run dry but no fuel goes to the BV

[Draw 3D]

Unless you changed tank heights between runs, that height is consistent so i would rule that out.

I would fill the tank and disconnect the line to pump and see if it flows, it almost sounds like something is blocking the tank output.

Also, I agree about tank level and pump height not being an issue, but only to a point.

If you do build a new tank, make sure the outlet is at the lowest point.

[noslin]

At this point, tank level and pump hight is not a player, the pump will draw the fuel.  I tend to have the front/bottom of the tank a little higher than the rear so that gravity helps feed the outlet.  Fill the tank full with water and the outlet capped, then pull the cap to see the fuel stream exit. should be a nice solid stream, surges and dribbles means that there is a problem with the vent. Try routing the fuel from shut-off back into the inlet side of the pump as when you shut it off the fuel just circulates and the pump doesn't run dry but no fuel goes to the BV

Just took the tank out, plugged off exit/feed.  filled it up, put cap back on, pulled plug on feed and it flowed without issue.  i did it twice, once without the cap, once with the cap on and the flow was comparative both times.  it just pours out.

on the pump, we have it with the loop line from fuel shut off to bottom inlet. Both bypasses go to the tank.  i didnt think it was a good idea to return to the main fuel line like i have seen on other cars for concerns of aeration.

For general knowledge on the Enderle pumps like this 110, what makes them go bad?   I took this one apart and to inexperienced it looks ok.  the brass is new but shows wear.  the gear shows no wear, there is no wear in the cover but the vane does show wear on the face.  i dont know how the gear teeth and vanes match up though.  so, just curious what kills them as they seem pretty fragile.

I ordered a waterman spur gear pump today.  we will get the system flowed again.

Dean

[Draw 3D]

Just took the tank out, plugged off exit/feed.  filled it up, put cap back on, pulled plug on feed and it flowed without issue.  i did it twice, once without the cap, once with the cap on and the flow was comparative both times.  it just pours out.

In my opinion, you should do all your testing with the tank in the car with the car sitting on the ground so you are duplicating actual conditions.

[dreracecar]

Its a process of elimination, You have fuel flow out the tank-so its not that. Again it should take a wrench to turn the hex and not your fingers, Running the pump dry and/or slamming the shut-off without fuel circulation, slams the impeller into the cover.When I killed my pump, it would fire but lose fire at the end of the burnout Looping fuel back into the inlet does not cause airation (imo) because as Waterman explained, its a closed loop hydrolic system and no way for air to enter. Most every car built now runs around a 10" crank hight, so all fuel pumps are at the same level and all fuel tanks run the outlet off the bottom, and no issues  for many--- whats your problem then???  Have you tried turning the motor over with the feed line to the BV disconnected?? Did somebody mess with the fuel shutoff and its off when you think its in the on position?, Did something happen to the HEX drive off the cam and its not turning?. Fuel systems deteriorate and need to be gone thru over time, But working one time and the next it doesn't, Something changed

Another thing I just thought of, was the pump cover removed and by accident rotated 180*  that will change the direction of the pump flow

[noslin]

  Running the pump dry and/or slamming the shut-off without fuel circulation, slams the impeller into the cover. 

Most every car built now runs around a 10" crank hight, so all fuel pumps are at the same level and all fuel tanks run the outlet off the bottom, and no issues  for many--- whats your problem then??? 

Have you tried turning the motor over with the feed line to the BV disconnected?? Did somebody mess with the fuel shutoff and its off when you think its in the on position?, Did something happen to the HEX drive off the cam and its not turning?. Fuel systems deteriorate and need to be gone thru over time, But working one time and the next it doesn't, Something changed

Another thing I just thought of, was the pump cover removed and by accident rotated 180*  that will change the direction of the pump flow

Thank you for the reply,  the night we went out and ran we were trying to start on the stand and the dummy driver (me) did not have the fuel on.    I think those four or five dry starts killed it i bet.  then when we went to run that first time he heard this noise like two metals rubbing which i think was the pump.

we didnt take anything apart at the track between runs so id rule out all the other concerns.  i think i just screwed it up with the dry start the first of the night thinking about it.

with the fuel system, we have the loop line, bypass off the shutoff to tank, and idle bypass off bv to tank.   Ill make a braided line setup for the loop line this time as others have mentioned they have had issues with those sucking air too.  You would think there would be no problems with brand new stuff but stuff happens. 

im hoping we get the pump fairly early next week as we would like to join the nor cal nostalgia eliminator group's race in redding ca