Electric fuel pump recommendation

[AlanCasida]

I was out with my Galaxie today for a pre-Drag Week 100 mile shake down drive. All went until I got about home. I stood on it real hard and it kind of stumbled then ran ok then stumbled etc. I had the presence of mind to look at my fuel pressure gauge and saw that when it was stumbling I only had 3psi fuel pressure and when it ran good it had 7 psi. I have long suspected this was happening but I never got to catch it. I am currently running a Clay Smith mechanical pump and I think the distance is too far for it combined with pulling it from the tank in the stock(albeit larger) location. I increased my fuel line size to 10AN(5/8) and that may have actually hurt, I don't know. Anyway I am looking at putting an electric pump in it now. I briefly had a Mallory140 pump in it but had problems with it. I also have one in my Mustang so I may try another one. Just wondering what you guys are running and if you are using the return style regulator. Since I don't think I really need a 5/8 fuel I could use it as a return and run a 1/2" feed line if needed.  I am also considering feeding the mech pump with the electric and just use the electric pump at the track. I had considered this before and was going to use a check valve in parallel with the elec to bypass while just running on the mech. I know there is a risk of blowing out the mech pump and pumping gas into my crankcase. That's why I abandoned it before.

[afret]

My street car has an Aeromotive 11213 Street Strip pump.  I had a Mallory 250 pump on there first but it was way overkill so I went with the Aeromotive.  I have a RobbMc return style regulator with a -8AN supply line and a -10AN return line.  I had a -8AN return line first but it wasn't big enough with the 250 pump to give enough control of the fuel pressure.  I don't think there is any problem having a large return line.  The stock eliminator car runs fine with the same fuel pump.

[BattlestarGalactic]

I wonder if the line size has anything to do with the ability to draw?  That is a tremendous amount of weight to pull forward under acceleration and wonder if the pump can't do it.  Maybe a std 3/8" line would work better with a mechanical pump.

I run a Mallory 140 with return regulator on the wagon for 15+ yrs now without issue at all(don't want to jinx it).  I like the return style regulator as it doesn't make the pump dead head, as I think that is hard on things.  Keeps the motor and the fuel cooler.

I used to run a Holley Blue pump for first few years, but got tired of having to fix the pump when it constantly would die.  I already had a 1/2" line, and just doubled it up for the return line.

[cjshaker]

I wonder if the line size has anything to do with the ability to draw? 

It most certainly would. The same amount of vacuum has much less effect when used on a bigger hose/tube/pipe or what-have-you.

Alan, I don't believe you had this problem last year, in fact you ran quicker than ever if I remember? It sounds like your pump is getting weak, and the bigger line will make it work harder to achieve the same result as a smaller line.

Something that always helps me to visualize something is to over exaggerate it. Imagine a pump pulling vacuum on a 1/4" line. Now imagine that same pump pulling vacuum on a 6" pipe. It's going to have to pull MUCH longer to achieve the same effect. It may seem over dramatic to state an example like that, but it shows that the difference is real.

[jayb]

FYI Alan, I had one of those pumps on my Mach 1 at Drag Week in 2005 and never had a bit of trouble with it.  I used a Moroso return-style fuel regulator and two 1/2" lines from the tank to the front of the car.  That is a really strong mechanical pump, and I don't think the rest of your system is the culprit.  You might consider taking the pump apart and seeing if an obvious problem presents itself.  On mine, when I first got it one of the check valves had come loose and was preventing the pump from doing any pumping.  I stuck the check valve back in and staked it in place, and never had another problem.

[AlanCasida]

Thanks for the replies guys. I got to thinking later that I might have a pump issue. Earlier this year when I tried starting it after setting for awhile and no gas was in the carb, I couldn't get any gas to the carb while cranking on the starter. I had to prime the carb to get it to run. Also yesterday it stumbled a little just passing a car on the highway. I'll pull the pump and take look at it look. I have a spare I can put in too. I am still thinking I might reduce my fuel line back to 1/2". I am using a RobbMc Performance deadhead regulator and a 1/4" return line to help prevent vapor lock as per his recommendation. I really don't want to completely reconfigure my fuel system this close to Drag Week if you know what I mean.

[AlanCasida]

I took my pump apart last night but couldn't anything noticeably wrong with it. I went ahead and put my spare pump on and even though I had completely drained the whole fuel system, I was able to get gas to the carb in about 45 sec of cranking time. Before I bet I cranked on it for 5 minutes without getting any gas to the carb. I did a few more checks tonight and put the car back on the floor. Tomorrow after work I'll take it for a short road trip and hit it hard again, this time with my track carb on and see what it does. I have ordered some 8AN hose to replace the 10AN if needed but I am leaning towards just a defective fuel pump right now.

[mbrunson427]

FYI, if you call RobbMc and ask nice he'll still make his 550hp or 1100hp pump for you. He had me do the leg work and find a usable donor pump that he could steal the diaphragm out of and then he built a pump. I sent him two donor pumps to look at and both diaphragms ended up being good (he said he usually has a 30% hit rate).

Like this:
http://www.ebay.com/itm/Genuine-AC-Delco-40345-GM-6416612-Fuel-Pump-/172606142901?epid=1451471802&hash=item283020b9b5:g:O4oAAOSwDmBY4GQX&vxp=mtr

[Falcon67]

Booth door cars here use Mallory 140s with return regs, zero fuel problems.  They both also use -8 AN lines up and back.  Had problems with an older BG 280 on the dragster - rebuilt and still problems, made two passes at 120 MPH with zero fuel pressure.  Using an old Holley blue now (with return) to get buy until end of season, then going to probably an ADP belt driven pump, #10 line, return reg and the whole deal so I can run gas or methanol.  Engine driven = no drag on the battery.  Aeromotive and MagnaFuel both sell good electric pumps also.  Make sure your pickup at the tank is sufficient to feed the pump you choose. 

[AlanCasida]

I took the car for a test drive with the new pump and my track carb, a 1050 Quickfuel and it will still briefly drop from 6 psi to 4 when I hit it with about 3/4 throttle but now it doesn't stumble. It doesn't seem to matter whether it's from a stop or cruising at 60 it will still dip down but it recovers. I think if I boost my fuel press to 7-8psi I'll be ok but I am looking at putting an electric pump in to feed the mech while at the track. If I do this I am going to use a check valve and bypass the elec pump while cruising so I don't have to draw gas through it while it's shut off. Since my '65 Mustang is more or less finished, this will most likely be my last DW & track appearance with the Galaxie and after that I am returning it to strictly cruiser duty. So right now I am just wanting to make it through. Thanks again for all the replies.