Will an electronic fuel pump help?

[rlgMcoupe]

I have a dual Weber setup and am happy with it's performance on the mechanical fuel pump, it's been consistently fun to drive for long time now. The one thing that is annoying is if I let the car sit for a few weeks the carbs totally dry out and getting gas to them takes some extra effort.  A lot of extra effort, I pump up the gas tank a bit with some compressed air ( i know this is not that safe, but I don't over do it) to create some pressure and then start cranking. eventually the carbs get wet and all is good. I was wondering if a swap to an electronic fuel pump would help this or if I should just go to the source which is possibly a tiny leak in the carbs bowls or gas flowing backwards from carbs back to tank when it sits. What do you guys think? 

Edited October 31, 2018 by rlgMcoupe
misspelled Weber

[halboyles]

Just put an inline valve near the tank that prevents the fuel from draining back into the tank.  Problem solved and cheap.

[rlgMcoupe]

Why do we overthink these things? That is not only cheap but super easy, if that solves this problem I'd be tickled. Been dealing with it for years now... thanks!

[Son of Marty]

Whats going on is gasoline chemistry has changed over the last 10 or so years and one of the changes being the removal or anti-evaporation additive because all newer cars run a closed loop fuel system and oil company's  ain't taking in older cars in to consideration gas and gasohol are back to evaporating about 5% of their weight at room temp per hour in a open container. So what does this have to do with our cars, well with out a check valve as the gas in the fuel line mostly in the engine compartment evaporates it expands and vaporizes, with out a check valve the easiest way to get rid of the presume is to push the fuel back to the tank and a check valve is one way to prevent this back flow and keep liquid in the system close to the fuel pump so it can prime it self quickly with out having to pump "air" the whole length of the line     

[Hans]

i gave up on check valve and went electric. i considered wiring/plumbing it as a booster pump, but decided might as well go all out. I used a pressure regulator. 

[Dudeland]

3 hours ago, rlgMcoupe said:

Why do we overthink these things? That is not only cheap but super easy, if that solves this problem I'd be tickled. Been dealing with it for years now... thanks!

PM Me I have a bunch, Will send for free just pay for shipping from Vancouver. 

[rlgMcoupe]

12 hours ago, Dudeland said:

PM Me 

 

Done, Thanks! Cheers! 

[TobyB]

It's an evaporation problem, not a drainback problem-

face it, the bowls in DCOE's are big enough to idle a car for 5 minutes

without a fuel pump running.

 

So yeah, electric pump WILL fix that problem...

 

t

 

[rlgMcoupe]

18 minutes ago, TobyB said:

It's an evaporation problem, not a drainback problem-

face it, the bowls in DCOE's are big enough to idle a car for 5 minutes

without a fuel pump running.

 

So yeah, electric pump WILL fix that problem...

 

t

 

Well, then... perhaps I was thinking about it correctly. The pump also seems like a pretty easy job, I'm going to add it to the list. Thanks so much for all the feedback. This problem has been annoying me for many years to be rid of it would bring a little extra joy to the cars ownership. 

[wegweiser]

If you decide to run an electric pump, I heartily suggest you get a high quality one, as well as a fuel pressure gauge / tester, and perhaps even a regulator, to ENSURE that you're getting about 3.0-3.5 psi and no more, at the carbs. Most regulators, pumps, and cheap gauges are woefully - and frustratingly inaccurate. Shop accordingly. I've found that the cheap Taiwanese chrome Summit Racing ones are pretty much useless junk…but Redline Weber makes / offers some decent ones, as does Pierce Manifolds. YMMV. 

 

HTH!

 

Paul

[Son of Marty]

Good advice on the electric pump use good equipment and be sure to include a inertia switch to shut off the pump in case of a accident.

[2002Scoob]

One thing that hasn’t been mentioned is to install an inertial cutoff valve. In the event of an accident it’ll keep it from ‘adding fuel to the fire’

 

-Trunk mounted Carter Pump, check valve in the trunk and at ahead of the carbs, dialed timing, broken in motor, S14 starter.

 

Now fires up in 2-3 seconds, every time.

 

 

Edit- Whoops, looks like internal cutoff was indeed mentioned, for some reason it didn’t show up on my phone. Worth emphasizing thou!

 

Sent from my iPhone using Tapatalk

 

[Dick R]

To cure the dry carb bowl problem on another old car (not a BMW), I installed an electric fuel pump in series upstream of the mechanical pump in the engine compartment. I continued to use the mechanical pump as the normal operating pump.  The electric pump was only used for filling the carb after sitting for a week or two.  I used a small push button switch that I mounted in an inconspicuous place under the dashboard.  The pump only ran while I held the button down.  It just pumped through the mechanical pump.  I did this so that I accomplished the goal of filling the float bowl without using an inertial cutoff switch for safety since the electric pump was normally not running. 

 

It worked quite well, but that was on an anemic 1700 cc V-4 engine with a one-barrel carb pumping out 70 HP on a good day when the planets and the moon were properly aligned.  A couple of two-barrel webers might want more fuel flow than a normal mechanical pump pulling through a non-running electric pump would allow.

[andyleonard]

We've been running a hot, twin dellorto 2 liter for 40 years with just a stock mechanical pump with no issues. Just in the last few years has the gas gotten bad enough to require action on the dry, cold start issue. The cure, which I went through today from soup to nuts including vacuum tests in the trunk and pressure tests at the carbs, is a cheap Purolator Cube which I mounted randomly on the firewall and triggered from inside with a small switch. It will fill the carbs promptly, has enough lift in the book and in real life to be mounted where it is, and makes an ungodly racket when empty but gets reasonably quiet when the gas hits it, so you know the exact moment the fuel hits the carb bowls. Obviously it pumps reasonably through the mechanical pump to do this and then once the car fires it gets turned off. Nice to have a spare pump already plumbed too, just in case.

[rlgMcoupe]

14 hours ago, Dick R said:

To cure the dry carb bowl problem on another old car (not a BMW), I installed an electric fuel pump in series upstream of the mechanical pump in the engine compartment. I continued to use the mechanical pump as the normal operating pump.  The electric pump was only used for filling the carb after sitting for a week or two.  I used a small push button switch that I mounted in an inconspicuous place under the dashboard.  The pump only ran while I held the button down.  It just pumped through the mechanical pump.  I did this so that I accomplished the goal of filling the float bowl without using an inertial cutoff switch for safety since the electric pump was normally not running. 

 

It worked quite well, but that was on an anemic 1700 cc V-4 engine with a one-barrel carb pumping out 70 HP on a good day when the planets and the moon were properly aligned.  A couple of two-barrel webers might want more fuel flow than a normal mechanical pump pulling through a non-running electric pump would allow.

This is very interesting to me and I was thinking about a similar solution, a pump to use as needed without having to crank the car. Thanks for the feedback. 

 

Also, related to a previous response, I see a lot of folks put that carter pump in the trunk. I have read elsewhere (non BMW) that a fuel pump in the trunk is a not a good idea. Would it be best to mount under car and in trunk is just easiest or is it safe in the trunk, no biggie? It's not like these things don't smell like gas here and there for all sorts of reasons anyway.