Carburetor Issues....

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Apr 7, 2012 | 11:51 AM

49truck

Thread Starter

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Joined: Jan 2011

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From: Easton on the Hill, UK

Carburetor Issues....

Hi

I started up my 1949 F3 today for the first time since I bought it a year ago (probably the first time its been started for tens of years!). I had overhauled and rebuilt various bits n pieces on the engine including the carb (7HT) and i also replaced the fuel pump.

The 226 fired up fine but revved up high and wouldn't idle (engine sounded very clean and crisp though which is good as it was a non runner when i bought it

), after i switched it off it then wouldn't start so I took the carb off and found fuel standing (about 1/2 inch) in the manifold so it had obviously flooded. The carb float level is correct and needle valve working as I checked all this when I rebuilt it.

Any ideas why its chucking so much fuel down the manifold? I wondered whether the replacement mechanical fuel pump was pushing fuel through at too higher pressure although it was a pump from Macs Auto for an F3 so should be right.

Any help much appreciated.

Thanks
Andrew

Apr 7, 2012 | 03:17 PM

oldmerc

oldmerc

Joined: Jul 2011

Posts: 1,538

Likes: 5

From: Edmonton,Alberta

Get a combination gauge (fuel pressure/manifold vacuum) and check fuel pressure anything over about 5 PSI is too much 3-4 is probably lots . As always consult the manual
I have been wrong before .

Apr 7, 2012 | 08:35 PM

GreatNorthWoods

Lead Driver

Joined: Apr 2002

Posts: 8,813

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From: Littleton, New Hampshire

High idle is probably a vacuum leak and the flooding is probably a bad needle and seat, trash, or stuck float...

Apr 7, 2012 | 08:46 PM

jniolon

old and in the way

Joined: Jul 1997

Posts: 5,924

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From: Lovely Hueytown Alabama

I agree with Vern... while everything worked on rebuild bench... a small dot of trash from the 60 year old tank/lines could stick in the seat and keep the fuel flowing... what type fuel filter do you have in the line ??? if none, I'd sure invest in one... several ways to check for vacuum leak... little spray oil around in places and the idle should change.. look for old hard hoses also

john

Apr 7, 2012 | 08:51 PM

ALBUQ F-1

Fleet Owner

Joined: Jul 2004

Posts: 27,299

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From: NM

An unlit propane torch (low setting) moved around the intake surfaces is less mess for finding vac leaks.

Apr 8, 2012 | 02:57 AM

49truck

Thread Starter

Freshman User

Joined: Jan 2011

Posts: 31

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From: Easton on the Hill, UK

Hi guys

Thanks for all your responses. I stripped the carb again and all jets etc were clear, float level correct and not sticking, and needle valve working too (at least when I blew down the pipe it was although I imagine the pump works at a higher pressure?). Maybe it's worth taking the spring from my old pump and putting it in my new pump?

All the fuel lines are metal so no old rubber hose, part of the reason why I haven't yet put an additional fuel filter in line so just relying on glass bowl on fuel pump which was all new. The tank was properly flushed too. Will break into fuel line and put a filter in as can only help.

Doesn't appear to be any vacuum leaks with all new gaskets used. There is a bit of play in the throttle shaft where it comes through the throttle body, I guess that could draw air. Aside from finding a new body it would need to be drilled and re-bushed.

Are there any GOOD replacement carburettors for a 226 H series that don't cost the earth???

Thanks
Andrew

Apr 8, 2012 | 07:34 PM

1952henry

Cargo Master

Joined: Jan 2004

Posts: 2,196

Likes: 351

From: Mandan, ND

Quote:

Originally Posted by 49truck

Hi guys

Thanks for all your responses. I stripped the carb again and all jets etc were clear, float level correct and not sticking, and needle valve working too (at least when I blew down the pipMaybe it was although I imagine the pump works at a higher pressure?). e it's worth taking the spring from my old pump and putting it in my new pump?

All the fuel lines are metal so no old rubber hose, part of the reason why I haven't yet put an additional fuel filter in line so just relying on glass bowl on fuel pump which was all new. The tank was properly flushed too. Will break into fuel line and put a filter in as can only help.

Doesn't appear to be any vacuum leaks with all new gaskets used. There is a bit of play in the throttle shaft where it comes through the throttle body, I guess that could draw air. Aside from finding a new body it would need to be drilled and re-bushed.

Are there any GOOD replacement carburettors for a 226 H series that don't cost the earth???

Thanks
Andrew

A good place to start, if everything else checks out as you say. You do have a flex line between frame and fuel pump, I hope!