Looking for suggestions on what fuel primer bulb fits 7.5mm ID fuel hose

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Emil Wojcik
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Re: Looking for suggestions on what fuel primer bulb fits 7.5mm ID fuel hose

#16 Post by Emil Wojcik »

All good information, thanks again to everyone. Yesterday I ordered new fuel hoses from Stoddard and the bulb from Amazon. Time to get ready for the driving season.
Emil Wojcik
'64 356C Euro coupe
'78 MGB
'86 Jaguar XJ6 Series 3
'94 MB E420

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Phil Planck
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Re: Looking for suggestions on what fuel primer bulb fits 7.5mm ID fuel hose

#17 Post by Phil Planck »

Remember to open petcock before using primer bulb.
Phil Planck

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Bob Cannon
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Re: Looking for suggestions on what fuel primer bulb fits 7.5mm ID fuel hose

#18 Post by Bob Cannon »

I am a big proponent of using primer bulbs in our cars which are driven only occasionally. My favorite placement location is under the car after the flexible fuel line exits the body. There are a few advantages for this spot verses in the engine compartment:
  • It is always filled with fuel under low pressure (gravity siphon) and is easy to access when you need to.
  • It does not show if you show your car and there is no issue of fuel leaking into the engine compartment if the rubber gets rotten. (an unlikely problem if you buy a quality bulb in the first place)
  • It's cheap and it works well to fill the carb bowls.


and one minor disadvantage:
  • You need to reach under the car to squeeze the bulb but this is only required infrequently, depending on how often you drive your car and how quickly the gas evaporates from the bowls during hot summer weather. Ladies are not a fan of this location, but for most guys who can get down and reach under the car, it's fine....
Here is a picture of a bulb during installation under the car; the small strap used to hold the fuel line works to hold the bulb as well:
primer bulb location under the car
primer bulb location under the car
If you want to install a primer bulb, make sure you buy a quality product which is USA made and resistant to ethanol. Stay away from cheap offshore bulbs; they don't last. I find a marine store such as West Marine is a good source for bulbs, since I can inspect them personally before a purchase. They come in 5/16" and 1/4" inlet/outlet sizes. The 5/16" version is 8 mm, which fits into a 7.5 mm braided fuel line with a "relatively" tight fit. I find I don't need to use clamps on the the lines and have never had leakage issues when using "ethanol-resistant" braided German hose. Always look for hose with "NBR" designation if you go with the braided fuel hose, such as that sold by Stoddard. If you use USA made non-braided fuel hose, you will have a difficult time finding 7.5 mm ID hose, since most auto supply stores carry either 5/16" or 1/4" ID hose; for this 5/16" ID hose you should probably use clamps on both ends of the bulb.

Using the primer bulb is easy-
1) make sure the petcock is open on the tank
2) reach for the bulb and start squeezing gently; you should hear the fuel running through the bulb into the line
3) you can stop when you feel the bulb getting harder to squeeze; it's a sign your carb bowls are filling up or full..
4) start the car and drive off.

Happy Motoring
Bob Cannon
Sacramento, CA

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Emil Wojcik
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Re: Looking for suggestions on what fuel primer bulb fits 7.5mm ID fuel hose

#19 Post by Emil Wojcik »

Thanks, Bob. If this were 20 years ago I'd put the bulb where you suggest. But the thought of having to reach under like that would probably be enough for me to decide it's not worth the effort just to go for a ride these days. Sucks getting old. ;)
Emil Wojcik
'64 356C Euro coupe
'78 MGB
'86 Jaguar XJ6 Series 3
'94 MB E420

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Mathieu Lecomte
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Re: Looking for suggestions on what fuel primer bulb fits 7.5mm ID fuel hose

#20 Post by Mathieu Lecomte »

I have one in my 912 and installed it between the tank and the pump (C type of pump), it works great when carb bowls get empty with the gas evaporating. I keep it on the driver side of the engine with enough hose so that the bulb is not directly exposed to heat of the exhaust and hot tin. I also change it every other year as a precaution to make sure the rubber does not perish because of the ethanol, no matter whether the bulb is rated for ethanol fuel. These are cheap enough vs. the cost of a leak and potential fire in the engine bay..

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