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Author Topic: Fuel dripping in carb after mechanical fuel pump replacement  (Read 1317 times)
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Shelley
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« on: 16 June, 2023, 08:40:32 PM »

Hi All,

We unfortunately seem to have run into yet another issue with our newly restored Fulvia S1.  Sad

We took the air box off a couple of weeks ago to fit a replacement "air box support bracket" to our car as it was missing after the restoration and we had read on this forum how the lack of support could put a strain on the rubber carb to head coupler (even this is complex as we discovered there are two different lengths of this bracket so we had to cut down the one we had bought to fit!)

After fitting the bracket, we reassembled and started the engine to test all was well only to notice that petrol was slowly dripping from the original Fispa mechanical fuel pump!

Therefore, given this is 54 years old and stood dry for 40 of these we thought best to replace this so we ordered a new one from Omicron.

We fitted this today and this is not leaking and seems OK but now we have another new problem!

The car starts OK but after running for maybe 1 minute we can see a lot of petrol dripping inside both inlets of the rear carb to the point that it pools and starts dripping out onto the drip tray, obviously the engine starts to misfire with this much fuel sloshing about.

The front carb seems completely happy with no drips at all.

We have a copy of the Omicron "Setting Fulvia Solex Carburettors" booklet which states that drips are likely to be cause by (in descending order of likelihood):

1). Incorrect Carb Float Level
2). Dirt preventing the needles closing
3). Excessive Fuel Pressure

The car was running well before we changed the pump so (1) seems unlikely? unless the new pump has raised the fuel pressure compared to the tired original one (3) could this mean that the higher pressure might raise the fuel level if the float level (1) wasn't quite right?.

Given we have disturbed the pump (2) seems the most likely scenario even though the fuel hoses and filter are new about 300 miles ago and we were careful to keep things clean when we were changing the pump (we have noted that our fuel filter is fitted before the pump but in the Lancia repair shop manual PDF it seems to suggest on some models the filter is after the pump? does anyone know what is normal?)

Therefore it would seem the next step would maybe be to check if there was dirt in stopping the needle closing or / and the float level is wrong? our main problem is that information (in particular pictures) on how to do this is very sparse, I think we are spoiled that for most things that go wrong now there is usually a YouTube video explaining exactly how to disassemble  / fix  / reassemble but not so it seems for the Solex C35 carb!

We have read quite a few posts from Tim "LanciaLulu" on the forum stating the fuel level should be 19mm from the top of the float bowl and that a cable tie can be used to check by removing a jet this but without pictures its quite hard to visualise how to do this for someone new to Fulvias and we are a bit nervous of just starting to undo screws on the carb without knowing what is "safe" to dismantle and what isn't.

Given all of the issues we are having we have booked to take the car to Omicron in a couple of months for a proper health check but in the mean time we just need to correct this issue sufficiently for it to be able to get there (as its about 100 miles away!).

If anyone has any photos (the more idiot proof the better) that would help us understand how to dismantle the carb to check the needle and float level that they could share we would really appreciated it, given the car was running OK before we touched the pump hopefully just cleaning / freeing something will be enough to get things going again!

Kind Regards,

Shelley



* rear-carb.jpg (262.54 KB, 2016x1512 - viewed 112 times.)
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dhla40
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« Reply #1 on: 17 June, 2023, 06:46:27 AM »

Do the carbs have a fuel return line?  If not get a filter king regulator and set to 3psi. The pump should have an internal filter gauze, if you have a filter before the pump make sure it is not too restrictive.

Sean 
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1976 1.3s coupe
1973 1.3s coupe
1982 montecarlo project
1976 alfa GT
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lancialulu
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« Reply #2 on: 18 June, 2023, 07:35:22 AM »

sent you a PM
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Its not the winning but taking part! or is it taking apart?
Lancias:
1955 Aurelia B12
1967 Fulvia 1.3HFR
1972 Fulvia 1600HF
1972 Fulvia Sport 1600
1983 HPE VX
1988 Delta 1.6GTie
1998 Zeta 21.  12v
Shelley
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« Reply #3 on: 25 June, 2023, 08:05:25 PM »

We have now fitted a Malpassi Filter King set to 3psi between the fuel pump and the carbs and the pooling of fuel in the carbs has ceased.

The Filter King fitted perfectly onto a bracket behind the fan so we feel that there was probably a Fispa regulator there at one stage.

Thank you for your replies Smiley
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