Club 80-90 Forums

I think I may have asked this question before but was never quite certain of the response.

1.9 DG, everything fine apart from this problem. I have a standard mechanical fuel pump, indeed everything is standard.

Leave it for two weeks and it takes a continuous 35-40 seconds of churning on the starter before it will fire, then it starts and runs immediately. Happens whether the weather is hot or cold. Good thing that the battery and starter are good.

So I assume that fuel is running back away from the carb. I do not think it is evaporation.

Is this possible?

Is there some form of non return valve, if so where?

If I were to fit a non return valve where would I put it?

Oh, it is evaporating, because your carb should retain enough petrol in the bowl to fire up .
However ,as well as this your fuel pump is the one way valve , its a diaphragm pump, which means by design it stops fuel flowing back from the pump to the tank as long as there is fuel in the pump . Are your fuel lines airtight ?

There are no leaks in  the line but I have been looking for petrol seepage, not whether they are are airtight. Thanks for the suggestion I will check that out first. The pump is original so I assume diaphragm.

Good point about the bowl though, there should be fuel in there. 

The DG mechanical fuel pump has internal non return valves. Probably knackered, fit a new one. Takes 20 mins tops.

silverbullet wrote: ↑04 Dec 2022, 19:23 The DG mechanical fuel pump has internal non return valves. Probably knackered, fit a new one. Takes 20 mins tops.

BW offer original Pierberg for £78.86 or made in China for £12.77  or an 'in the middle' job for £21.59

What would you do?

Never knowingly buy Chinese crap?

Yeh, buy cheap get cheap.

Bit late in mentioning but has the vehicle been tried starting using the cold start procedure after been idle for so long.

If you mean the one press on the accelerator before using the starter then yes it has.

Sometimes takes more than one, depends on how cold and left idle like mine but I get the point.

I used to suffer badly from this, and had always put it down to parking on a sloping drive with the tank downhill a bit from the engine, but sounds like it was more likely a faulty non return valve in the pump.

Rather than flatten the battery cranking the engine in the end I used to disconnect the fuel hose at the pump outlet, push a small funnel in the the tube and pour fuel directly into the carb before reconnecting everything back up. A bit drastic but it would always start first go with a full float chamber!

Eventually I fitted an electric pump close to the tank. It still seems to suffer from the draining back/evaporation issue but it's a lot easier to get everything primed with the electric pump. Makes a bit of a racket but don't think I'll change back now.

I used the van yesterday. It is now stone cold. When I go out and try it will start first time. Leave it where it is for a week or two whatever the temperature and it will take its customary 30 seconds of churning.

As suggested I'll double check hose unions and then get another pump (not the Chinese one!)

Any further suggestions much appreciated

This forms the basis of a simple and logical plan, the only sort of plan I understand!


Ta all

Old thread sorry...

In order to try and improve bad starting after long periods I have now replaced the fuel pump. No problems under normal use but leave the thing for a couple of weeks and it still takes ages and ages to fire and run (ie things are unchanged despite new pump). Leave it overnight in current temps and it is happy to start straightaway on a frost covered morning. 

So where is the fuel in the carb going? Is it really evaporating  in there in January?!

I've got a similar issue, but thinking it may be due to hydraulic lifters draining down when left for a prolonged period.
I've left the van for a couple of weeks then opened up the Solex carb, which still had plenty of fuel in the bowl.

But when the van is left standing then needs longer cranking to start, it always starts about 2 seconds after the oil light goes out (indicating oil pressure established by turning the engine over on the starter, and lifters pumping up?).

But wouldn't the lifters then make a terrific racket if they had drained down? 

Ihadn't thought of that. Our oil light goes out quite quickly, well before the engine starts after a long slumber.