my dad put a 3 deuce intake on his 51 merc flethead over the winter. he used 1/4 inch line from the fuel block to the carbs. he took it for a ride today and it seems to be running out of gas. it has 3/8 line from the tank to the block. it has 5 lbs of fuel pressure. it goes like hell until the rpms get high then it just falls off. any help will be appreciated.
If you have a filter in the line it could be partially clogged. I have a 1939 9n tractor with a 4cyl flathead and it was doing the same thing. Come to find it was only running on 3 cyl because it was puking oil on the plug.
Look for a fuel line/filter/tank/fuel block or carb blockage and test the volume delivered by your fuel pump.. BTW, 5lbs of fuel pressure is too much unless you regulate it down to 2-2.5 psi for the carbs. What carbs/reg are you running....? No FH will use more fuel than a 3/8" line can provide on the street hehe.
it's a holley red pump with holley fuel regulator. there is a filter, he already changed that, it was the first thing he looked for. the carbs are ford 8ba. he raised the float level also.
Is it a mechanical fuel pump ? might need an electric one .or do some work on the motor to fix the mechanical pump problem .if Im correct the flat head fuel pump works off the cam shaft .when the lobe or rod wears off the fuel pump will stop working .that is why guys with flatheads have electric pumps on their cars .Its an easyer way out .
What indications are you experiencing to make you think you are running out of fuel? Was the engine pulling good through the rpms before the carb/manifold swap? Were any other changes made with or since the swap?
the pump is electric. it is mounted in the middle of the car. it ran just fine before the swap. in low rpm it goes gust fine. as son as you start to hammer on it it just falls on its face. .
OK, Simple check, disconnect the carb fuel line, run it over the side into a can and see how much fuel it will pump into the can! That will tell you if the pump will pump enough and if the line will pump enough! then pull the needle valves and make sure that two of them are not stuck closed, or something similar. Now if the carbs are full, and the lines and pump are good. pull the main jets on the carbs to check for clogged main jets on any carbuerators. Main jets good, everything else good, it is not your fuel system. Be sure to check each line that goes to each carb to make sure there is not a crimp or obstruction in the individual lines traderjack
Reading this again, I am confused about what you mean. What falls off, the engine power, or the fuel pressure? Traderjack
Hard to diagnose over the internet. Check to see if the choke plate is partially closing (sucking shut) during acceleration. 3 carbs are too much as trader jack said.
You said it "falls off" so I assume its not misfiring stumbling or breaking-up. I would blame fuel delivery. Clogged fuel pickup in tank; clog or break in fuel line (sucking air?); low float levels in carbs. You say 5lbs, but that's a static measurement, meaning that it can accumulate that pressure at idle. You need a volume measurement to see if you are outpacing the pump when you run WOT. Most electric fuel pumps are designed to "push" and not "pull" and should be mounted close to fuel tank. You say your's is mid-vehicle. That may be the problem. You could also temporarily swap manifold for single carb and test it out to see if it Revs out.
Hello..If the electric fuel pump is to far away from the fuel tank you can have problems..Also, 5 psi is to much..Holley makes two fuel regulators, HP and LP.. I think it's fuel pump location..???????????????? Remember elec. FP are pushers not pullers.. Duane..
Other than saying the power falls off, you have not said anything to make me think it is a lean fuel problem. Usually you will get some popping back through the carbs with a lean condition. Without more information, I think you are barking up the wrong tree. Pull a plug, I'll bet it is black with soot. More information please. good luck,
A thousand years ago, my coupe had a similar problem. Would putt around ok, but ran out of gas anytime I leaned on it (which, of course, happened all the time; I was sixteen). Turns out that the seat was loose in the carb housing, and vibration unthreaded it a little. This altered the float level to the point that any time the motor was under load much more than idling along, it leaned out. I realize that this is sort of a remote possibility, but it happened to me, and was an important lesson about how frustrating these things can be....
Are you using the stock distributor? If so, you are probably not getting proper spark advance with the 3 2's. It will be retarded.
<HR style="BACKGROUND-COLOR: #e5e5e5; COLOR: #e5e5e5" SIZE=1> <!-- / icon and title --><!-- message --> Hard to diagnose over the internet. Check to see if the choke plate is partially closing (sucking shut) during acceleration. 3 carbs are too much as trader jack said. <!-- / message --><!-- sig -->__________________ yes I had a choke stuck on my carb setup . it would idol but would die when I tried to drive down the road . check that . plus I agree .the electric fuel pump should be as close to the gas tank as can be.Fun hu ?
A friend of mine has a '53 Merc with a flathead. He had the same problem but his electric fuel pump was mounted by the firewall. Some told him to mount it by the tank so it could push instead of pull. That cured his problem.
Have you taken the sparkplugs out to look at them? Is it lean or rich? Ether condition can cause problems. The guys are right about the electric fuel pump. They are made to push fuel so it need to be mounted close to the fuel tank.
I have used Electric pumps on the last 5 Shoebox Fords I have owned, and the best place I found to mount it is on the driver's side frame rail. Just in front of the rear axel. All or most Electric pumps are pushers..I found that in this position the pump also gets the benifit of a sifon action from the tank cuz it is in a lower position...bye the way 3 deuces are not too much for any Flathead..I am in the process of setting up another Electric pump for the present Shoebox I have ..I am using a carter vane pump. been using Carter pumps since '65..using a Holley Regulater factory set at 2.75 PSI..I use 3/8 line from the tank and 5/16 to the carbs..Your 3 Duces need to be properly set to get the full benifit of the system.
we finally found the problem. it was the one thing that we overlooked. it was the 4 inch piece of hose from the tank to the hard line. it had a slice on the inside. when the pump sucked, it pulled the sliced part almost closed. it is hard to believe a dollar part gave us so much grief. thank to all who gave advice.
The Jalopy Journal
