Easier Starting

[oldcoupe]

This may be a help if, like me, you run your CS infrequently.

The starter has to churn over for quite a time until the fuel gets through to the carburetors and the engine will fire. It's hard on the starter and battery, and the neighbors think your old car never starts properly. If the battery is a bit low to begin with, then there's a chance it will go flat first.

I put a small primer pump for an outboard motor (cost $7) in the fuel line up on the engine bulkhead before the inline filter and fuel pump. A few squeezes- you can hear the carbs filling up, and the engine always fires first or second try.

It's true that taking a few turns on the starter first gets the oil up into the engine, which is good if it hasn't been run for a while, but an E28 oil filter unit seems to stop all the oil running back down.

 

[gwittman]

I just installed an electric fuel pump in the gas line before the mechanical pump and turn it on until it builds up pressure before trying to start. Then I turn it off and let the mechanical pump do it's job when I fire the engine.

 

[Bill Riblett]

Hah. I just use a spray can of starter fluid, at least on the cars with downdraft carbs where you can pop off the airbox lid easily. Doesn't work so well on Weber sidedrafts...

 

[Tierfreund]

Walloth and Nesch sell a much simpler and cheaper solution to the same problem. Since the fuel lines run dry on carbed cars that are not driven daily (simple gravity), they advise to install a little valve in the fuel line just before the (mechanical) fuel pump to keep it from running dry

Look here at "non Return Valve"

http://www.wallothnesch.com/e/fuel/fuele9.htm

 

[jmackro]

I just installed an electric fuel pump in the gas line before the mechanical pump and turn it on until it builds up pressure before trying to start. Then I turn it off and let the mechanical pump do it's job when I fire the engine.

What make/model pump did you install? Clearly it needs to have low enough resistance to allow the mechanical pump to pull fuel through it when the electric pump is shut off.

Once the electric pump was installed, whey didn't you just bypass the old mechanical pump?

I have been planning this same modification: The mechanical pump in my CS hasn't been changed in the 18 years, 80,000 miles that I have owned the car - it may even be the original. Since the car is only started occasionally, it does take some cranking (or squirting gas down the carbs) to get it to fire.

Bill: I really dislike spray ether - it seems to work TOO well. Whenever I use it, the engine fires immediately, and I can hear the rods knock for the first few revolutions since the oil pump hasn't spun enough to build up pressure. Just squirting a little gasoline into the downdrafts seems to work better for me.

 

[x_atlas0]

Carl Nelson sells an electric fuel pump used in carb conversions. You could rig it to a switch, let it bring the system up to pressure, kill it, then start the car. I'd actually make it in parallel to the mechanical fuel pump with the other line using a non-return valve, that way you wouldn't have to worry about draw-through issues.

 

[gwittman]

The problem is the carburetor bowls evaporate fuel and get low. Keeping fuel in the gas line will not help that.

I don't remember the make and model of the electric fuel pump. I will take a look at it tonight. It is basically just an inexpensive, generic pump. Initially, I was concerned that it might cause a restriction when turned off but after at least 5 years of use, it has not created any problems even at WOT red-line excursions.

The reason I don't use it all the time is I don't like the vibration sound it makes and I don't know how much pressure it builds. I feel better using the pump BMW engineers called out.

Yes, squirting fuel or starting fluid down the carburetors will work. I prefer to just get in the car, turn on the ignition and push a button, wait a few seconds then fire it up. Call me lazy.

 

[oldcoupe]

The primer bulb was so low-tech and low-cost, took five minutes to fit, has a non-return so does the same as the W&N part and, as has been pointed out, the carb bowls can take quite a lot of filling.

I haven't posted before- thanks for the feedback!

 

[gwittman]

The electric pump I installed is a Purolator POR#42S. It is called a universal electronic fuel pump.

 

[OCCoupe]

you can buy a regulator from any auto parts store. The boys over at Mesa Performance said that webers like 3.5psi which didn't work for me, mine work better at 5.5psi. Whatever pump you buy, the box will indicate the psi and you can buy an adjustable regulator, just put the regulator in the engine compartment, psi's will drop from the trunk to the engine bay.

 

[gwittman]

I know regulators are readily available but I have always tried to avoid extra items if I don't need them because it is just something else that can fail or give problems. I have always used this principle (call it KISS if you like) with my Austin Healey Sprite race car and that has served me well. With it I use the stock fuel pump which regulates it own pressure. I do run two just in case one fails. SCCA won't let me run two engines in case one fails but that kind of breaks the KISS principle anyway.