I'm currently running the stick mechanical fuel pump in my 50 flatly along with an electric pump. Starting to think running both simultaneously might be the cause of my motors hesitation under load. Anyone have any experience with this setup? Should I eliminate the mech pump?
It could be too much fuel pressure,the Ford 94's only need about 2.5 psi so you should check that it is not much above that.It is common to run an electric pusher to the mechanical pump in these old Fords to prevent vapor lock especially with the summer temps in Phoenix.If the pressure is higher Holley has a low pressure fuel regulator available.
Yep. Just installed that exact regulator. While it's better, she still hesitates under load. Psi is currently set at 2.5. Thinking maybe the fuel/air mix is off?
Many old carburetors had an adjustment on the accelerator pump. If yours is not in the winter setting, that could be the hesitation.
I agree, missing under load is often ignition related. However while we're on the subject, my flatty came to me with an electric pump back at the tank in addition to the stock mechanical. I removed it before even getting the car running thinking it unnecessary. And it does run fine without it, but if it sits for a couple of weeks and the carb (97) dries out, no amount of cranking or choke will fire it up, needs a prime. I'm considering putting the electric back to see if it alleviates this issue. The accelerator pump works fine once there is fuel back in the bowl.
A lot of guys run both normally using the electric just as a primer. In answer to the question I would not rule out the combo being a problem until I found out what the problem was, but hesitation should not be caused by too much fuel. if you are getting too much fuel you will notice it at lower speeds, it would be an eye burner and loading up. If its not loading up at idle you can pretty much rule out a too rich problem and move onto something else.
You mean toggle the electric on just to get it started? Hmm, never thought of that. And it will still pass enough fuel when turned off? Mine looks like this.
I had the same sort of set up for the same sort of reasons on a 421 Pontiac tri power. I had no problem with getting enough fuel through the electric pump when the electric pump was off. As stated above it was just used to prime the carbs or in a vapor lock situation. Just remember to shut off the electric pump when it is no longer needed (ask me how I know that!)
I run the same setup on my 40's and use as beaner mentions to prime it after it sits a while-works fine-have left in on a few times with no issues but run a regulator by the carb.
Sounds good. I try to keep my hot rod electrical needs to a minimum but it would sure beat removing the air cleaner and priming all the time. Ha, I wonder if one could accomplish the same thing with one of those outboard motor squeeze bulb things. My line runs close enough to the rocker panel that I could conceivably reach down and grab one.
I have given that some thought before, I actually have used a boat tank to get one running before. Not as a permanent thing mind you but to get an old hooptie moving under its own power. You could spend a lot of money on a traditional hand pump and use it only for priming. Stick the bugger up on the dash and everyone will think you are a real racer.
Caution guys! When buying one of these small electric pumps (I call them thumpers), be sure it is made by Facet Corp (could be NAPA or Purolator but still MADE by Facet). Had a buddy that just installed TWO of the Chinese Knock Offs and BOTH were bad!! Went and got a real Facet manufactured thumper and presto, all was OK! BTW, I've been running one on the Stude for 12 years and 45,000 miles - no problem! Of course I carry an extra just in case!!.......Also be sure to mount these pumps and a 45 degree angle with the outlet highest and as close to tank as possible...Joe Facet's site: http://www.facet-purolator.com/cube-fuel-pumps.php
Thanks all. Hadn't thought about the ignition possibility. I'll double check everything and see whats what.
I run an electric booster feeding the stock SBC pump that I wired through an old Chevy windshield wiper/washer switch installed where the choke pull cable would be, and parallel power through an old TH400 throttle kick down switch so when the Q-Jet goes to WOT I don't get a lean detonation after 3 seconds. I can push the wash switch to prime, switch the wiper switch on for a sustained load pull like towing up a hill, or mash the gas and get the extra fuel it needs on demand. Everything works fine with the booster off under normal cruise.
Fordoors, sorry your thread got a little side tracked, but the title was appropriate. For the ignition, if it sounds like it's cutting out on all cylinders check the points and replace the condenser if you have them. If it sounds like just one cylinder is cutting out check the wires. But you knew that already.. Fan Attic, that is some ingenuity right there! I have a TH400 with a horn button on the shifter for the kickdown, love it that way. So I was just checking out my flatty truck, the only convenient place for a squeeze bulb primer is under the hood near the mechanical pump. Not sure if that would work since it would have to pull all the way from the tank in back. Might try it anyway, they are only about 10 bucks. On another note, my chainsaw refused to run very well today, and after limping through a few branches I realized the bulb primer on it, which I replaced less than a year ago, was dried and split, from ethanol I gather. Hopefully the outboard primers are more resistant.
Have a flow through pump to prime the flattie pump after sitting, then turn off. Have a DPDT switch, on, off momentary on to prime or run in addition to stock (don't need it). When at high speed, engine would falter and die unless I was quick to turn the elec. pump on. Found out a hose clamp at the rubber to metal line was loose and the stock pump sucks air easier than fuel. Now its tight and no problems.
For a priming system, run 2 fuel lines into a "Y" . on one side put a cheap [Chinese pump ], on the other side put a 1-way "check valve" once the system is primed, you can either leave the pump going or switch it off. The mechanical pump will draw through the check valve OK. I did this on a diesel when playing with WMO fuels. [ the primer pump used to clog up around the electro magnets ]
Care full running both electric and mechanical at the same time. You could have a bad diaphragm in the mechanical pump and it could fill your engine with gas. Run electric with a regulator.
OK...I've installed a fuel pressure regulator (set to 2.5) with no improvement. Also changed out the 6v fuel pump to a 12v model. Checked the timing and all plugs/wires, all good. I did convert to an electronic ignition and am thinking there might be an issue with that. Newly rebuilt carb. Still hesitates under load/when I floor it. Thoughts?
Airtex E8016S – 12 volt – 2.5-4.5 psi – 30 gph flow – 5/16” inlet & outlet fittings These pumps will both be flow thru pumps that will allow fuel to be pulled thru them when the pump is off
LOL I have an old original airtex pump I keep for a spare pump in the garage as we speak. they were the real deal back in the '60s. You cannot wear one out.
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