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Car stutters and stops - fuel pump problem?

Joolzy

Enthusiast
Messages
32
Location
Portugal
Hi Everyone

Trying to establish if we have a fuel pump problem and also what fuel pump we need to replace it with, read on and you'll see what I mean.

When out driving recently the engine started stuttering and then it would pick up again.
Having recently had the fuel tank off to replace the tube from the filler cap to the tank and repair a leak we took it all off again to ensure no blockages from tank to carb (filter etc), all now clean.
Suspect that the fuel pump might not be pumping efficiently as the fuel filter seems to empty quicker than I would expect whilst the engine is running.

So, on to the fuel pump. Fitted is a Sofabex and therefore not a standard part. It is fully sealed so cannot take apart for inspection.
The sofabex pump seems to be operated by a rod which goes between the fuel pump and the engine making the pumping action.
It has an inlet, outlet and pipe to the carb.

Questions:
1) Anyone any experience of this potential fuel starvation issue?
2) What is the correct fuel pump for this engine - 1108cc?

Have attached a photo of the Sofabex type of pump and engine

All help gratefully received

Engine.jpg Fuel pump.JPG
 
Try checking the fuel filter, had a similar problem on one of our cars - due to dirty fuel there was a grimy film that under load got sucked onto the filter paper and caused fuel starvation.
 
Sofabex (later taken over by Valeo) were often installed as originals.
This one is a later type (sealed) earlier ones was screwed
so you would've been able to check and replace both nylon filter and also gasket/membrane inside..
You should have no problms locating a replacement (eBay/Classicos etc)
(I gather you've already checked that the fuel-cap is ventilated and/or not blocked.) -R.
 
Hi

That is the correct fuel pump and a good quality one too. As it seems you have checked the system from the tank to the fuel pump. You could now investigate from the pump to the carb. Firstly, check fuel delivery from pump to carb. A simple check is to disconnect the hose from the fuel pump to carb at the carb end. Turn over the engine with the hose facing away from the car, if the fuel gushes out, it is a sign the pump is ok. Reconnect and investigate the carburettor. Check for blockages in jets, main jet in particular, check the gauze filter on the inner side of the brass connector which the fuel hose from the pump to the carb is connected to, at the back of the base of the carb/manifold there is a breather hose which runs to the rocker cover, it has a one way valve inside it, if the hose is split, the valve faulty/missing, this can cause issues which seem like fuel starvation. Failing the latter, complete strip down of carb and clean/rebuild. If problem is not resolved, investigate ignition side of things.
 
Sofabex (later taken over by Valeo) were often installed as originals.
This one is a later type (sealed) earlier ones was screwed
so you would've been able to check and replace both nylon filter and also gasket/membrane inside..
You should have no problms locating a replacement (eBay/Classicos etc)
(I gather you've already checked that the fuel-cap is ventilated and/or not blocked.) -R.
Many thanks do you know of suppliers in mainland Europe? Also part number would be very useful as have looked online and haven't been able to find one that looks the same.
 
Hi

That is the correct fuel pump and a good quality one too. As it seems you have checked the system from the tank to the fuel pump. You could now investigate from the pump to the carb. Firstly, check fuel delivery from pump to carb. A simple check is to disconnect the hose from the fuel pump to carb at the carb end. Turn over the engine with the hose facing away from the car, if the fuel gushes out, it is a sign the pump is ok. Reconnect and investigate the carburettor. Check for blockages in jets, main jet in particular, check the gauze filter on the inner side of the brass connector which the fuel hose from the pump to the carb is connected to, at the back of the base of the carb/manifold there is a breather hose which runs to the rocker cover, it has a one way valve inside it, if the hose is split, the valve faulty/missing, this can cause issues which seem like fuel starvation. Failing the latter, complete strip down of carb and clean/rebuild. If problem is not resolved, investigate ignition side of things.
Many thanks, will check as you suggest.
 
Hi Andy
We don't have a box that was just an image that I got from Googling.
Hi
The pump in the link I sent you will fit if yours is the 2-pipe, pushrod-operated type like the one in the Google photo.
Renault #: 7700666046 (See Oscaro page for other manufacturers' equivalents).
 
Thanks everyone for replies. Unfortunately still having issues.

The car starts fine, runs for a short time and then ‘coughs’ and stops like it’s running out of fuel.
Have replaced the fuel pump, checked and cleaned carb, numerous times. Checked and cleaned petrol tank and checked pipes are free from dirt/blockages.
It will not pump fuel. Take pipe off carb and fuel pumps correctly. Put it back on carb and no fuel pumped through.

Have also put on new HT leads and checked timing.

Any ideas gratefully received.
 
It sounds like the float in the carburettor isn't working properly and is restricting the fuel flow. If the pump works properly there's nothing wrong with the fuel tank, pipes or pump it suggests the problem lies in the carburettor itself.

Have you checked the level the float at which the float sits? If it sits too high the supply of fuel is restricted, and if it's too low the carburettor may flood. Have a look & check this-good luck!
 
Inside van carb_LI.jpg
- Is the float retaining piece in place correctly?
- Ditto the washer under the needle valve.
- The needle valves sometimes go - will it fall under its own weight, and is there too much lateral movement? Sometimes they seem to work fine and then suddenly stick.

P1030103 (3)_LI.jpg
It's worth checking that the tube/jet with the blue arrow is clear - a piece of very soft thin wire works well.
There's a filter under the doorbell-like cover that hardly ever gets cleaned. You can fill the hole (yellow arrow) with carb cleaner, drain, dry and then blow through with an airline/footpump, or drill out the rivet and replace with a screw (this was such a common problem with 28IFs that you can even get a repair kit). If the rivet's still in place, the filter's probably dirtier than it should be!
Van carb top_LI.jpgP1030086.JPGDoorbell filters.jpg
 
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Plenty of things to check there! Another point to make is that if the float is damaged it might sink under the fuel or float too high above it, thus affecting the amount of fuel the carburettor receives.
 
Thanks both for this help, much appreciated.

Have checked everything you’ve suggested.
Needle valve is at correct height according to manual.
I have however, ordered a rebuild kit which includes a new needle valve.
There is some improvement in the running and it is definitely smoother but the engine still stutters and almost stalls after a few minutes like it’s running out of fuel. If I pump the accelerator pedal it will pick up and run smooth again for a period of time and then repeat the stutter/almost stall.

Tomorrow I plan to check the ignition timing. I also have new plugs to fit.

Thanks again for all the suggestions.

I’m also thinking of changing the carburettor completely, as I have a life! Are there any suggestions for good replacements to the Zenith?
 
Hi there Jools -You claim you've got a life -Do tell the rest of us here on the Forum about how That feels...
-far as I know most of us on here hasn't got one..... (not even sure we would want one come to think of it :whistle:
Suggestions for a good replacement for a Zenith -How's about a working one? Postalservice has gone OFF
their rockers lately-if not I've got a complete one but it'll cost you an arm & a leg (+uma dúzia de bacalões
da Noruega) to get it to you down Portugal-Even have a 32 mm Hennesy Hop-up one.

boa noite/-Reid.
 
The saga continues.....

and so does the running problem.

Put the new needle valve in and it ran worse so put the old one back!

Fitted new fuel pump, new filter (and relocated), new plugs and HT leads. Checked timing.

The pump is pumping fuel to the carb via the filter. There is fuel in the float bowl after the car stops.

Carb: Float is working and not damaged. Filter checked and is clean.

I'm running out of ideas now my friends.

Still it runs and then after a couple of minutes stutters and stops. It's like it gets warm and the problem starts.

Any more ideas?
There's a carburettor repair company in Leighon Buzzard, England:


I've used them before and they're very good. Not cheap, but good and thorough!
Thanks for the info, but I am in Portugal
 
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- Does it make any difference if you remove the fuel filler cap?
- As jcarruthers2 mentions above, it's critical to ensure that the arrowed pipe/restrictor/manifold connection/rocker cover are really clean (it looks as though your car - and perhaps all Portuguese GTLs - has a different restrictor system; on UK cars/vans the restrictor is in the pipe):

1635869043024.jpeg

Could you post a few photos of your carb/distributor area?
 
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