The Stovebolt Site Forums The Shop Area Engine Shop electric fuel pump in 54 chevy 3100

when i got this pickup the guy told me that he had installed a fuel pump because he was tired of it vapor locking? I'm tired of hearing the pump run. the line is running thru the original pump and then to the carb. for some reason the carberator constantly has gas leaking out of it and around it. could the electric fuel pump be doing that and can i go back to a regular fuel pump. why would he not have bypassed the original fuel pump. what cause vapor lock.

The electric fuel pump could have too much pressure causing flooding or the carb just needs rebuilding. Yes,you can go back to a mechanical pump. Vapor lock is when the fuel boils or vaporizes in the system preventing sufficient gas flow to the carb to run properly.Sometimes rerouting the carb fuel line away from engine heat is all that is needed.

supposedly the carb was rebuilt but I'm beginning to doubt some of what he told me. carb kits are not that much so probably will just get one. i think mine is a rochester from looking at some pics i've seen. as far as rerouteing the gas line that isn't a big deal. will get me away from that pecking whinning when the key is on.

know is the electric fuel pump is routed thru the old pump wouldn't that put more pressure on the carb? unless they deactivated the mechanical pump somehow?

Vapor lock is caused when the gas does not move fast enough in the fuel line and has time to get hot, turns to vapor and then stops. This can easily be caused by a weak/dead mechanical fuel pump; it is an "easy fix" to add an electric fuel pump to solve this issue. I would therefore put a new mechanical fuel pump, just in case yours is weak indeed.
Most electric fuel pump will push more volume/pressure than a mechanical one, so that could be why your carb leaks, the pressure has blown some gaskets.
A good mechancal fuel pump with the proper size line will not allow vapor lock.
The nice idea about having the fuel go from an electric pump through the mechanical one is that it looks stock...

(The nice idea about having the fuel go from an electric pump through the mechanical one is that it looks stock...)

but it creates problems as far as I'm concerned. I have been wondering if it was causing to much pressure. you guys just afirmed my gut feeling. guess i will have to order a new mechanical fuel pump and carb rebuild kit with the gaskets. hopefully oreillys has them or at least can get them the next day. i want to get them put on this weekend. I will then put the electrical pump on the shelf to collect dust.

Just a suggestion.....your electric pump can be put on a "momentary" push button switch and used as a backup for supplimenting your mechanical pump in the event you have issues with E10 fuel. That's the setup I've been using to overcome fuel pressure loss caused by engine heat soak.

Secondly, it wouldn't hurt to regulate the fuel pressure from your mechanical pump. I'm running a dual carb setup with an inexpensive Mr. Gasket adjustable regulator and 3-1/2 psi at the carbs is adequate. If the PO was having vapor lock (phase separation) issues I'd also suggest you make sure your steel fuel line doesn't sit too low between the valve cover and thermostat housing. It might not look "cool" but neither does a truck with the hood up cooling off the engine compartment so that you can restart the engine. This is where the momentary switch on the electric pump will force cool fuel through the line and the engine will refire. Hope this helps.

Dave

ok if i understand you correctly i should disconnect the electric pump from the direct on and hook it up to a push button switch so that in the event that things stop working it hit the button (kind of like a horn button) and away i would go. as far as carbs i only have 1. how do i check the psi at the carb. what type of gauge that is.

I have an electric fuel pump on my '55 1st Series, and I like it. I have no problems at all with leaks or too much pressure. The only time it makes any noise is when I start the truck, for about 20 seconds you can hear the ticking. It does not run through the stock pump, which I left in place. As for "vapor lock"; it is a rare condition. When I was a kid, I recall that vapor lock got the blame every time a car would not start..."you probably got a vapor lock." An old, well regarded mechanic clued me in one day. He said that many people came in with auto problems that they attributed to "vapor lock", but ultimately it was always something else.

This vacuum gauge and fuel pump tester was a common and necessary (and inexpensive) tool that most back-yard mechanics had in their toolbox.

http://www.automotivetoolsonline.co...el-Pump-Tester-Mityvac-5511_p_12358.html

http://www.harborfreight.com/cpi/ct...&zmas=12&zmac=112&zmap=93547

I also doubt that vapor lock is the problem if lines are standard diameter and standard location (on a 216/235/261). Nonetheless, using a vapor-lock home remedy is not difficult or expensive.

Without knowing the pressure from your fuel pump, it is premature to consider a fuel-pressure adjuster.

The gauge/tester above is cheap and available at most parts stores. It can be used for a variety of diagnostics. And, it can be used to set the timing (not optimum - timing light is better) and the carburetor (better with a tachometer) on these engines.

Adjust the carburetor.

http://www.earlycuda.org/tech/vacuum2.htm

http://www.gregsengine.com/vacuum.htm

http://www.tuningmadeeasy.com/tuning/vacuum-gauge-the-wonder-tool/

Fuel pressure test is at the bottom of this page.

How to make a fuel pressure gauge.

go ahead and get the carb rebuild kit,but don't do anything with it until you check the fuel pumps first.I had an electric pump on my custom corvair,when the fuel pump would'nt stop pumping it would floodout through the venturies,so try pumps first then if carb still leaks you can still rebuild.

I have had an electric pump inline on my 39 Pontiac with a chev.v8 for many years. i have it on a manual switch. I only use it to pump gas up to the carb. when it has been sitting for awhile for a primer instead of grinding the battery down.I was at a show 200 miles away a few years ago when the fuel pump started leaking. I couldn't get to it to replace it in the parking lot, so I plated the hole joined the lines together and drove home with the electric pump. Good backup. My pump is a low pressure about the same as the manual one for a v8.