5 replies to this topic

[lachlan1275gt]

Hi, I have a 1275gt with a weber 45dcoe I can’t get started again since breaking down.

I was driving along, and the motor started to bog down/splutter under max throttle, then under mid, then any throttle at all, then cut out, within ~1 minute. Turns over but absolutely nothing, occasionally fires once, sometimes have a strong fuel smell (from exhaust sometimes?).

I checked and re set the distributor point gap, distributor hasn’t shifted, still has a nice blue spark on the plug. I have taken the carb off and cleaned it out with some carb cleaner and blew out all the jets twice. Fuel flows into the float bowl and stops as expected as the level rises.

<300kms before this problem began I swapped the old carburetor out, for the current one, in doing so I noted the manifold gasket was patchy in places, I put a thin layer of red RTV on the gasket to fill in the gaps with plans to replace it if it became an issue.

The only other minor thing is I remember hearing a high pitched (spinning?) noise coming from the carburetor for a few days before this happened. Could something have come loose within the carb? 

Does this sound like an air leak? I’m not sure what else to check. I think I’ll replace the manifold gasket anyway.

 

Thanks

 

 

[Earwax]

Hi Lachlan

 

Regarding the spinning noise - it would be wise to check the aux venturies are still in their correct place being held by the grubs screws - and often locking tab  - when adrift these stuff up fuel delivery. - 

 

If you do need to take the carb off - check under the  plate between the two circular inlet port - there is a spring to assist throttle shut off - if it comes loose or breaks then it can interfere with throttle plate opening and closing.(Warning if you choose to take this off/out use eyewear -   spring under load and hard to get at)  I delete this in track car as we use double external springs to bring the throttle back to rest)

 

It is also worthwhile just eyeballing through the ports- fully shut throttle -  transition holes just in play usually  and fully open - full 90 degree opening.

 

I personally like the soft gasket - and not done up too tight ( it is one of those jobs I usually set the tightness and then worry about air leaks under vibration , so tweak a bit tighter - but resist this temptation)

 

I have found the one piece 'bikini style" rubber mount kits are less fiddly to work with.  Good luck 

[lachlan1275gt]

Hi, excellent thanks for all that I'll have a look tonight hopefully.

 

To be clear I already use the soft type of gasket between the carb itself and the carb manifold, the gasket I was referring to was the exhaust manifold.

[timmy850]

Might be worth doing a compression test too

[sonscar]

I would fit a new inlet manifold gasket, noise could have been worsening air leak.Steve..

[lachlan1275gt]

Found one of the auxiliary venturies grub nut had come slightly loose, meaning the venturie could move the sliiiightest amount.

 

Fixed that and changed the manifold gasket and it started immediately. Thanks everyone!

 

Running pretty rough (uneven can't clear its throat and occasional backfire) but I think that's just from me messing up the timing somehow when checking the points gap