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Low Cost Fuel Priming Solution: the Squeeze Bulb

September 27, 2010 | Troubleshooting & Repair

By Tom Farnam


[Editor: it's common for the 356 engine to be difficult to start if it has been sitting for weeks or even several days, as modern gasoline is more volatile (evaporates more easily) than 50's and 60's era gas, resulting in the gas in the carburetor float bowls drying up. One solution is to install an electric fuel pump, but a less expensive solution is described below. See these links for information on electric fuel pump installation in pre-1962 cars (T5 and earlier) and in 1962 and later cars (T6). Another alternative is the Precision Matters "Primer Reservoir".]


If you want a primer pump, there is a very simple way to add one to your 356, without making any modifications which aren't easily reversible. It's only a primer pump, and will not operate your car if your fuel pump quits working, but it take care of the challenge of starting that car after it's been sitting a while. If the car has been sitting long enough to need priming, simply crank a bit for oil flow before using the priming pump. And it's cheap (under $15) and easy to install.

All you need is an outboard motor primer bulb (they look like this) available at you local boat shop or online.

They cost about $5 or $6 each (get the one for 5/16 inch hose, that's virtually equivalent to the standard 7mm fuel line) and even with shipping it will be under $10.

For a "C" fuel pump, merely install the bulb ahead of the fuel pump in the engine compartment, using standard American 5/16in. I.D. fuel hose (comes in 24 in. packages) and standard stainless steel hose clamps. Pull the hose leading to the fuel pump off its fitting and attach it to the bulb input fitting. NOTE - there is an "in" and "out" side to these primer pumps, marked by words or arrows, and the "out" side should be towards the carburetors in the fuel flow circuit.

For earlier cars, the primer pump can be put in place of the flex line section in the line which leaves the fuel pump heading for the carburetors. The primer pump and fuel pump will both permit the flow through and suction effects without difficulty.

Then attach the 2 ft. hose to the other bulb end and looped it around the carb preheater horn, or use a plastic tie-wrap to hook it to the latch cable housing, just be sure the bulb rests away from anything hot.

I've had one on my SC-engined Roadster for over two years, and no leaks or problems. Plus it's easy to keep an eye on them during your pre-start inspection (you do that, right?). Below is a picture of the installation – simple and very effective.

Using it is simple. Open the engine lid, reach in and squeeze the bulb until float bowls are filled. My Solex 40Pii4's take about 6 or 7 squeezes until the bulb gets very hard to squeeze because the float valves have closed. Added benefit, if you don't get resistance on the bulb, there may be a float valve issue or other fuel line leak.

2 Comments

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Richard Pike
May 25, 2012 at 7:44 PM
A great fix! I installed one of these bulbs in my '58 Speedster (big Solexes) last year. After squeezing the bulb until the carbs fill -- even despite weeks (or months) of sitting idle -- the engine starts on the 2nd or 3rd brief crank of the key. Dick Pike
Profile missing thumb
Richard Pike
May 25, 2012 at 7:44 PM
A great fix! I installed one of these bulbs in my '58 Speedster (big Solexes) last year. After squeezing the bulb until the carbs fill -- even despite weeks (or months) of sitting idle -- the engine starts on the 2nd or 3rd brief crank of the key. Dick Pike