Getting 356B started

356 Porsche-related discussions and questions.
Post Reply
Message
Author
William Boyd
356 Fan
Posts: 52
Joined: Wed Sep 28, 1994 8:38 am
Location: Murrells Inlet, SC

Getting 356B started

#1 Post by William Boyd »

I wanted some advice at getting my 356B started after a period of not being run. I usually pour some gas into carbs and after a few tries it runs. this time it does not keep running. I have a new battery and just put in new spark plugs.
After it sit awhile it fires once. After putting gas in carb it runs about 10 sec. I don't like this method of starting but don't know if I should just keep pouring more gas in carbs. I have also replaced the fuel Petcock with a new one. I put fresh gas in tank after changing that out. Any advice on what to do next would be appreciated.

User avatar
John Brooks
356 Fan
Posts: 2146
Joined: Tue Jul 08, 2008 11:50 am
Location: Whidbey Island WA.
Contact:

Re: Getting 356B started

#2 Post by John Brooks »

Turn on the gas petcock. engine sounds OK but not getting ant gas form the tank. I usually fill the bowls with a hypodermic (25cc) it will run for 45-60 seconds on the bowls alone.
John Brooks

62 Roadster
66 912
84 Cab
getting pushed around in porsches since 1965

User avatar
David Jones
Classifieds Moderator
Posts: 7323
Joined: Tue Mar 25, 2008 6:32 pm
Tag: I wish I knew as much as I think I know.
Location: Kentucky

Re: Getting 356B started

#3 Post by David Jones »

Are the accelerator pumps working? If not then you may have plugged jets, secondly you may have a bad fuel pump, fill the fuel bowls through the vent hole in the middle of the carbs.That should run the engine for a couple of minutes.
If I had known I would live this long I would have pushed the envelope a little harder.
Cymru am byth
David Jones #9715

User avatar
Doug McDonnell
356 Fan
Posts: 6061
Joined: Sat Apr 05, 2008 8:21 am
Location: Augusta,Michigan

Re: Getting 356B started

#4 Post by Doug McDonnell »

Easy to loosen a fitting to see if you are getting fuel to the pump. If not you can us air (with adapter from old milk jug) and your shop Vacuum with the hose on outflow, to add just a little pressure to your gas tank filler to aide in getting gas to your pump. If you are getting fuel to your pump then maybe a pump rebuild is needed. Just keep checking along the fuel path and determine where you are not getting fuel.
1965 356C 2000 BMW 740i Sport 1967 Honda CL77 There is never enough time to do it right, but always enough time to do it over.

William Boyd
356 Fan
Posts: 52
Joined: Wed Sep 28, 1994 8:38 am
Location: Murrells Inlet, SC

Re: Getting 356B started

#5 Post by William Boyd »

what is the best way to check the fuel pump?

User avatar
Doug McDonnell
356 Fan
Posts: 6061
Joined: Sat Apr 05, 2008 8:21 am
Location: Augusta,Michigan

Re: Getting 356B started

#6 Post by Doug McDonnell »

If you have fuel to the pump you can either 1. check to see if fuel is up to a banjo bolt on the carb or 2. attach a low pressure fuel pump meter to the outlet. Only 3 LBs or so of pressure needed.
1965 356C 2000 BMW 740i Sport 1967 Honda CL77 There is never enough time to do it right, but always enough time to do it over.

William Boyd
356 Fan
Posts: 52
Joined: Wed Sep 28, 1994 8:38 am
Location: Murrells Inlet, SC

Re: Getting 356B started

#7 Post by William Boyd »

I don't have a pressure meter so i am not sure what to expect but I disconnected fuel line to pump. Gas flows freely in the line. next I disconnected coil wire and pump output hose from metal lines going to carbs. put the end of the hose in a empty water bottle, turned the engine 3 times for 15 seconds each. the bottle got about 1 ounce of gas in it. I was expecting to get more so I am thinking the fuel pump is bad. Any advice on whether this is a good test of the pump would be appreciated.
Thank you to everyone who has responded to my post.

User avatar
Doug McDonnell
356 Fan
Posts: 6061
Joined: Sat Apr 05, 2008 8:21 am
Location: Augusta,Michigan

Re: Getting 356B started

#8 Post by Doug McDonnell »

Unsure which type of pump you have as both were used during 356B production. Bruce rebuilds them as do others I am sure: http://www.sparkingplugs.com/6.html I would at least put 15-20CC of gas down each carb vent tube as others have suggested to see if it will run for a few minutes.
1965 356C 2000 BMW 740i Sport 1967 Honda CL77 There is never enough time to do it right, but always enough time to do it over.

William Boyd
356 Fan
Posts: 52
Joined: Wed Sep 28, 1994 8:38 am
Location: Murrells Inlet, SC

Re: Getting 356B started

#9 Post by William Boyd »

Getting the gas into the carb vent tubes has worked to keep it running much longer. It still quits after a while. maybe the gas is not getting back into the carbs. It has been at least 20 years since I rebuilt the carbs so maybe I need to at least take them apart and clean them. The problem has to be the carbs or the fuel pump. I think I will look into getting a pressure gage to check the fuel pump first. Thanks for all the advice, at least I know the engine is running good when it gets the gas.

User avatar
David Jones
Classifieds Moderator
Posts: 7323
Joined: Tue Mar 25, 2008 6:32 pm
Tag: I wish I knew as much as I think I know.
Location: Kentucky

Re: Getting 356B started

#10 Post by David Jones »

Fuel pump diaphragms lose their elasticity after decades of use. There is a good chance that you will need a new one.
If I had known I would live this long I would have pushed the envelope a little harder.
Cymru am byth
David Jones #9715

User avatar
David M Patrick
356 Fan
Posts: 104
Joined: Sun Aug 06, 2017 8:40 pm
Location: Lexington, KY

Re: Getting 356B started

#11 Post by David M Patrick »

Might be the screen "filter" inside the pump is clogged.

William Boyd
356 Fan
Posts: 52
Joined: Wed Sep 28, 1994 8:38 am
Location: Murrells Inlet, SC

Re: Getting 356B started

#12 Post by William Boyd »

Thank you, I will check the screen filter tomorrow

User avatar
Harlan Halsey
356 Fan
Posts: 2339
Joined: Fri Mar 02, 2012 2:05 pm
Location: No Cal SF Peninsula

Re: Getting 356B started

#13 Post by Harlan Halsey »

Your test in post 7 is good. You should get much more that 1 oz after 15 sec. Your pump is bad. Probably needs a new diaphragm. You can check the valve function by blowing through the pump. You can bolw through in the flow direction, not backwards.

Post Reply