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Manta B Carb adjustment and hot start issues


Simon Dobbo
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On 07/11/2024 at 17:56, Simon Dobbo said:

Stripped it off and cleaned it and put back with sealant for now

not split but warped

drove 97 miles to NEC no issues 

but haven’t stopped it and let it cool and tried again - will leave that for another day

does seem to have a little less go - I think it may be too rich now as you say

i know have original jet sizes so maybe I can find some at the show this weekend

Guess you made it home ok On Sunday!

Nice to meet you Saturday & Sunday. Just remembered I had an issue with my old 1.8. It used to cut out occasionally. It was the electronic ignition module not earthed yery well on the inner wing.

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4 minutes ago, Vince said:

Guess you made it home ok On Sunday!

Nice to meet you Saturday & Sunday. Just remembered I had an issue with my old 1.8. It used to cut out occasionally. It was the electronic ignition module not earthed yery well on the inner wing.

Thanks

I had some issues on the way home.

Did about 40 miles no bother - then on M42 at 70 it started to splutter and die. Made it into an emergency layby. after 2 mins managed to start it again with full throttle.

Pulled out and got another 3 miles and it started doing it again.- Dropped down to third and gave it full throttle - eventually cleared and kept it going.

Then it did another 60 miles home without another issue - except for my nerves - HA

I think I am going to check and remake the earth connection at the weekend and then remove the pressure regulator between the fuel pump and carb.

Will then have to ssee how it goes again

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15 minutes ago, cam.in.head said:

maybee i missed it in an earlier reply but why have you got a pressure regulator ??

was fitted by previous owner when they did the weber conversion to get the car running after the 30 something year lay up.

I am told by many that a Weber needs a pressure regulator as they only like 3 to 3.5psi and pumps do more than that.

But at the NEC several club members say I dont need it - some of them running Weber without for years.

Possibly fuel starvation when on motorway on way home for sure.

I am getting to end of my knowledge with it but it wont play up when i take it anywhere.

😂😩

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30 minutes ago, cam.in.head said:

cant see any reason why a webber would be any different and require an additional pressure regulator to any other carb. varijet, solex etc . surely its a simple float/ needle valve .

the proper mechanical pump only supplies a low pressure anyway in the order of 3-( psi

Im not sure myself.

If I google it many places say its a must on Weber and people have had carb overflow issues but I am sceptical. That is far more likely on electric pumps I would think. Some say they had issues with mechanical pumps putting out 6psi causing an overflow but my plimbing brain thinks the float valve should easily cope with shutting off a low pressure such as that.

I will be removing and trialing on Saturday if i get time before a cheeky week in Teneriffe starting Sunday.

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the mechanical pump works different to an electric one anyway.

the lever moves a diaphragm which only pumps fuel though a one way valve if theres anywhere for it to go .otherwise even thou the rod moves in and out the diaphragm stays put until it needs to return  and gets the next rod push . sort of hard to explain but its not as if its trying to push  fuel through at every revolution. 

if some people are saying that a normal ( std issue) low pressure mechanical pump can flood a weber then does that mean they use a different fuel valve to other manufacturers ?   cant see it !

however . easy enough to try without it and see . thought youd sorted it with the carb mounting issue . ( unless its still got an unseen crack ??)

 and     

does it actually need the rubber mount ?

can if be removed , fitted direct or some kind of plate ?

why were they there in the first place ? does the 1.3 ohc or 1.6 ohc have one ??

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3 minutes ago, cam.in.head said:

the mechanical pump works different to an electric one anyway.

the lever moves a diaphragm which only pumps fuel though a one way valve if theres anywhere for it to go .otherwise even thou the rod moves in and out the diaphragm stays put until it needs to return  and gets the next rod push . sort of hard to explain but its not as if its trying to push  fuel through at every revolution. 

if some people are saying that a normal ( std issue) low pressure mechanical pump can flood a weber then does that mean they use a different fuel valve to other manufacturers ?   cant see it !

however . easy enough to try without it and see . thought youd sorted it with the carb mounting issue . ( unless its still got an unseen crack ??)

To be honest the hot start/running issue may or may not be sorted. I havent tested the theory yet. Once I rebuilt it I went all the way to NEC in one go and then turned off for the 4 days - then drove home in one go and parked again.

But i did get the new sypmtom of it cutting out on the motorway but starting again after trying for a minute.

I am hoping that that may have been lack of fuel at high speed with the regulator restricting flow to carb but not sure.

Definately taking it out and trying for a bit.

Also thinking of replaceing the fuel pump as it drains back so not sure non return is working well.

Pump looks new but if its like any other bits previous owner did then its cheapest possible parts - the ignition amp was poor and lasted about 400 miles

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11 minutes ago, cam.in.head said:

as far as i know the 1.8 doesnt have any antidrainback valves just the normal 2 pull push inside the pump . there are always plenty of new pumps on ebay even the orig ones so it will do no harm in trying one .

its certainly an unusual issue this . 

I wont let it beat me! - HA

 

Not sure if the pump should have a spacer between it and engine? which i think is missing.

Seem to remember reading about a spacer somewhere

Need a closer look but sure its just on a paper gasket. - so spacing could be an issue withpump not operating fully/correctly.

I bet spacers are impossible to get.

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find a delco pump as orig and fit a spacer to be sure . someone will have one or make one from some fibre insulation or suitable heatproof material .around 5mm thick .

if yours just did a non stop trip to the show without issues thou a doubt the spacer is an issue BUT gm fitted it ( as a heat barrier i believe mainly . ) so might as well fit one and a pump to eliminate it from your enquiries( doing away with the regulator too) . then after that find a replacenent distributor to eliminate the hall sensor then youve pretty much covered everything ! 

i dont doubt for one minute that it will beat you but it sure is annoying when its a stupid issue like this that seems to be fighting you ! 

good luck / happy tinkering !

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the hall sensor in the distributor is the same as fitted to many gm cars of the era . without having one to compare you may just be able to swap the baseplate complete ( easier than the actual sensor as its rivited on with some non conventional stud rivets ) or someone may well have a spare for you . need to confirm next time that spark is actually being lost ? like it was before 

but

the distributor sensor is a pretty reliable component which appears to be working correctly or you wouldnt be able to do a long journey as you did ?      just be nice to eliminate it 

i have had a loss of spark issue once on a belmont ( identical system) and replacing the distributor baseplate solved it . i suspected the connection on the connector on the side of the distributor because there was the slightest hint of green crusties in it !  

 

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2 hours ago, cam.in.head said:

the hall sensor in the distributor is the same as fitted to many gm cars of the era . without having one to compare you may just be able to swap the baseplate complete ( easier than the actual sensor as its rivited on with some non conventional stud rivets ) or someone may well have a spare for you . need to confirm next time that spark is actually being lost ? like it was before 

but

the distributor sensor is a pretty reliable component which appears to be working correctly or you wouldnt be able to do a long journey as you did ?      just be nice to eliminate it 

i have had a loss of spark issue once on a belmont ( identical system) and replacing the distributor baseplate solved it . i suspected the connection on the connector on the side of the distributor because there was the slightest hint of green crusties in it !  

 

yeah, great point. Most of the parts can be pulled out of the same era distributors as the internal plates etc are all common components. Just the Housing and shaft ofc that is different.

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astra and cavalier distributors . none 1.8 specific but should be same internally for spares ( dont quote me 100 % on that ) but shows they are available if you cant get a manta one on the omoc.     if were me i would try the regulator removal as the first step then if it does if again confirm spark present or not .

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After changing pump and regulator ensure the rubber fuel pipe from tank to plastic fuel pipe is new. I had a manta hatch 1.8 that had air getting into fuel feed due to rubber pipe breaking down caused similar issues as you are having. 

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10 hours ago, rutts said:

After changing pump and regulator ensure the rubber fuel pipe from tank to plastic fuel pipe is new. I had a manta hatch 1.8 that had air getting into fuel feed due to rubber pipe breaking down caused similar issues as you are having. 

Thanks

I have replaced the pipe from the tank to the fuel pump completely but i will re check connections.

I I thinking the regulator and connections are causing the issue and ossible air ingress.

Will be removing and replacing with new piece of pipe this weekend if i get time

10 hours ago, ®evo03 said:

Have you looked at emissions, mine wasn't fumey and driving well, but was off the scale on emissions, suspect carb spacer perished. 

The rolling road tune went through the emissions

He said was running too lean hence the larger jets etc.

But he missed the air leak under the carb which i confirmed with brake cleaner spray causing engine to stall.

I dont think my rubber is split or perished - its more the metal plate in the rubber is warped causing a bad surface to bolt the carb down to.

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If you want to bin the weber I have a perfect condition varajet 2 carb and manifold with a great condition rubber mount too. 
I have just taken it off my 1800 coupe and that car could start and drive from one end of the country to the other no bother at all.  
£100 

It gave great power delivery and never let me or Kyle down   
Sounds good too!

 

 

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