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Citroen Specials Club

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Petrol pumps

I am a new member with a Lomax. The car runs well, but would not restart when hot last time out. I know that this can be common fault, I also know that the mechanical fuel pump is a pain to work on. Could a SU electric pump help with hot starting problems? I was thinking of fitting one and leaving the mechanical pump with its hoses intact as a stand by in case the SU failed, belt and braces.
Any ideas? thanks

John

Membership No. 1798

Re: Petrol pumps

Hi John. I have SU pumps on both my Lomax & DRK. These things are old tech. but
very reliable. They do stick if left for a few months but a sharp tap will get them going. Failing that, cleaning the points does the job.
I've never failed to get one going yet.
I removed the mechanical pump for the Lomax & blanked off the aperture. I keep it in the car in case of emergency.
I tried a 'Facit' ('solid state' no points) pump on the DRK but after burning out two of them I bought an SU. That was 14 years ago & it's still going strong.
SU's are available new from Burlens in Salisbury.
Recommended.
Cheers, Mike

Membership No. 46

Re: Re: Petrol pumps

Thank you Mike,
Do you think an SU would help with hot starting? Does your car suffer from this with the SU? I thought that running a fuel line away from heat as much as is possible would help, the mechanical pump gets very hot. Where have you fitted the SU? If hot starting is connected to petrol evaporating could twin carb motors be free of the problem? I usually turn off the engine on a normal car in traffic hold ups, I would not risk it with the Lomax. Mine still has the fan and cowlings, what do drivers of fanless motors do in long traffic snarl ups?
John

Membership No. 1798

Re: Re: Re: Petrol pumps

How old is your coil, older ones tend to lose their sparks when they are getting on a bit, does the coil feel overly warm to the touch when restarting is a problem, this normally is a good sign of a failing coil

Membership No. 174

Re: Re: Re: Re: Petrol pumps

I would agree that the coil is the problem...fit a different one- if good and see how it restarts when hot. It is a long standing problem.
As to overheating in traffic, when standing idling, the motor is really just pushing pistons back and forth with no kinetic energy or heat produced...its when you rev up to pull away that the oil needs to be pushed into the bearings...and then pull away.
If you fit thermocouples to the plugs, you will find that the temperature at the gauge actually drops in traffic and rises as you pull away.reverse to logical thought.
so just blip the throttle after standing at the lights to charge the motor with oil and then drive away...

Membership No. 1336

Re: Re: Re: Re: Re: Petrol pumps

Hi
Try piggy backing another coil,and when it wont start just swop the leads over . At least it will cut out one option.
Ray

Membership No. 1540

Re: Re: Re: Re: Re: Re: Petrol pumps

Thanks for all your help. I was told when I got the car that it may have 123 ignition. Not sure about this yet. Will have a look into this. Spares with the car included another petrol pump, what looks like a petrol pump refurb kit and a tool that looks like it is for removing petrol pumps. I will try a new coil. I know a 2cv owner who is convinced that hot starting problems are related to fuel evaporation.

Cheers John

Membership No. 1798

Re: Re: Re: Re: Re: Re: Re: Petrol pumps

Hi again John. The std. 2CV coil is a well known discussion point. They DO overheat & the engine will not restart until the coil has cooled. I know that there are some alternatives to the Citroen coil (perhaps someone could advise John?)

As to positioning; on the Lomax it's right at the back fixed under the floor adjacent to the petrol tank. On the DRK the under bonnet space gets very hot so the pump is on the bulkhead on the passenger side.

It you fit a SU it's very worth while fitting a pressure regulator (Malpassi?). If the fuel pipe should fracture, this device will immediately shut off the fuel.

I did'nt have one of these fitted to a Marlin I owned. The fuel pipe fractured & the ensuing fire was most impressive!
Ah, forgot. Always carry a fire extinguisher!

Cheers, Mike

Membership No. 46

Re: Re: Re: Re: Re: Re: Re: Petrol pumps

Hi John (again)
If you dont have a 123, the CSC sell the Boyer Branson which retains the points. Its much cheaper and works well for me .

Ray

Membership No. 1540

Re: Petrol pumps

Hi Mike,

You mentioned that you removed the mechanical pump for your Lomax and blanked off the aperture. I intend to do the same on my engine, but I'm concerned that if I just remove the pushrod, there may be some follower or operating mechanism that is free to rattle about or drop into the crankshaft or camshft.

I've looked at parts catalogues and manuals, but I've not found what drives the pushrod.

Can anyone confirm that it's safe to remove the pushrod without worrying about also removing anything else.

Best regards

Paul

Re: Petrol pumps

I've had no end of trouble with 2CV petrol pumps. They seem to be all pattern parts made in the Peoples Republic and don't take too well to being left to stand for a week or two in between uses. It's the little valves that go and then the pump is not repairable. After I'd fitted 3 in 2 years I decided to go with an SU pump. Every last part is available, they can be rebuilt and even converted to electronic operation. They are also kinder to your battery and starter motor than a mechanical pump in a car that doesn't see everyday use. That's because you don't have to turn the engine over and over to get petrol in the carb bowl. Just wait for the pump to stop ticking and it fires right up.

I just pulled the push rod and made a plate -never had a problem and never heard of anyone who has. If the plate was thick enough you could drill a relief hole for the rod and leave it in there.

BTW - the coils are problematical as they get older but nobody building a kit car replaces them because a wipe with a paraffin soaked rag and, voila, they look as good as new (but they're not....)

A Boyer Brandsen and twin coils have done excellent duty on my Blackjack - covering nearly 75,000 miles (more than it did as a 2CV). I replaced the coils this year but the BB is going strong.

Re: Petrol pumps

As someone has already mentioned try moving the petrol pipes away from the manifold or any source of heat .

Membership No. 1540

Re: Petrol pumps

Hi Geoff,

Thanks for that information. Someone had already fitted an SU pump, so the mechanical pump was just taking up space. Anyway, 6 mm dural plate is made up and ready to go on.

Best regards

Paul

Re: Petrol pumps

The petrol pump pushrod is activated by its own cam on the camshaft. Removing the pushrod will not cause any damage.

Rgrds
C

Membership No. 1595

Re: Re: Re: Re: Re: Re: Re: Petrol pumps

Overheating is caused by fuel perculation in the float chamber, the cure is to fit a cooling fan energised through an auir temperature switch controlling the fan so when the engine is turned of the fan continues to duct cooling air to the carb, a la Volvo 340 with the Renault engine.


regards Carole aka friend Brian!

Membership No. Hon/015J