petrol pump problems

[VERAT25]

hi

t25 1.9 dg petrol c reg
got a small issue with the van starting.
when I try to start,i have noticed that petrol is not being drawn up by pump into filter/ carb.
the petrol in pipe seems to disappear when van is parked, but no evident leaks.

to start van I have to prime the carb(pour petrol thro pipe, also do same same to pipe leading to tank)
this gets the van running,then seems ok until I park up for 2 weeks, then same again.

could this be the pump, as it seems to work ok when van is running????

any ideas please

thanks

pete

[kevtherev]

OK first off you need to lose the filter in the engine bay, it's just plain dangerous.
The fuel falls back because air is able to enter the fuel delivery system at the highest point, and the fuel falls back to the tank level due to gravity,
Could be from a tiny hole in the pump diaphragm.
Alternatively..
It could be that the pump is fighting a vacuum because the tank outlet is blocked or the filter is blocked

Fitting a non return valve near the pump (Brickwerks) will immediately solve the problem.
Although it's only getting around the issue, not resolving it

[itchyfeet]

Fitting a metal ( not plastic) non return valve near the pump (Brickwerks) will immediately solve the problem.
Although it's only getting around the issue, not resolving it

a plastc non return valve is a dangerous as a plastic filter Brickwerks do a metal Pierburg one for 10 quid

[kcbart]

That worries me - mine has 3 plastic fuel filters, 2 of which are in the engine bay! In addition to the one under the van by the petrol tank, there is one next to the carb before the fuel pump and one in the return pipe from the carb.
So next job on the list is to put a metal non return valve in place of the filter before the pump and get rid of the filter in the return line by replacing that whole piece of tube.

Many thanks for pointing this out,

[R0B]

Why would anyone put a filter on the return line.? Let alone in the engine bay.

[bigbadbob76]

Had the same problem on my ranger a while back, it was corrosion around the feed fromthe tank to the pump letting air in and allowing fuel to drain back down to the tank.
Sounds like something similar could be happening to yours. worth checking the fuel lines, filters and metal spigot on the tank.

[kevtherev]

That worries me - mine has 3 plastic fuel filters, 2 of which are in the engine bay! In addition to the one under the van by the petrol tank, there is one next to the carb before the fuel pump and one in the return pipe from the carb.
So next job on the list is to put a metal non return valve in place of the filter before the pump and get rid of the filter in the return line by replacing that whole piece of tube.

Many thanks for pointing this out,

If you don't have a problem with fuel running back you don't really need a valve.
More importantly, when were your fuel lines changed?

[kcbart]

I replaced all the fuel lines soon after I got the van about 3 years ago. I left those filters in the system as I assumed they should be there - now I know better.
Re the non return valve, I was thinking this might reduce the time spent cranking the engine when it's not been used for some time.

[MGP]

The fuel pump is a diaphragm pump, it is the one way valve, fitting another is simply a bodge to mask the problem.
Get yourself a vaccum pump with a gauge, remove the fuel lines from the fuel pump, connect your vacuum to the inlet on the pump and pull a vaccum, if the fuel pump will hold a vacuum then it's OK and your problem lies with the fuel lines, if not replace the pump.
You could also use the vacuum pump to test the fuel lines by blocking off one end and pulling a vacuum from the other end.
At the end of the day you have a problem with your fuel system, a problem which could potentially end up with a breakdown, why wouldn't you find the fault and fix it?

Sent from my SM-G920F using Tapatalk

[kevtherev]

Agree entirely with MGP.

Fuel falling back to the tank is like the incontinence in old ladies.... Old age = leaky valves.

I have to admit the lpg system I fitted years ago has saved me from this issue.

[kcbart]

Many thanks, everyone, for the information and help. I will be following your advice.

[itchyfeet]

Can somebody please explain why the float chamber store of fuel does not overcome tge common fuel drain down problem, there should be enough there to start and run long enough to pump new fuel up.

With my lpg I run the float chamber dry so I can understand if you had LPG but normally when you stop the float chamber is full.

I suppose after months it would evapourate but surely not in a couple of weeks?

[Oldiebut goodie]

Possibly heat soak from engine if no insulator fitted between carb body and engine?
( couldn't hide stuff in ships engine's air filters if recently run and stopped as they were too hot, same principle)

[VERAT25]

thanks all for the input.
will take it all on board.

are brickwerks the best place for new fuel lines, do they come with the plastic pipe on inner.

thanks kev for filter advice, will sort that when I fit new lines and pump(if required).

I would have thought if pump ok it would have enough suction to pull fuel wnrn trying to start( only a thought)

cheers
verat25(Cardiff)

[captain Byrne]

I replaced all my fuel lines and the pump after encountering a similar problem but the issue still persists. The fuel line still empties and the van takes an age to start after it's been sat for a week or two.
Anyway, I now have an electric pump which I'll be fitting soon after Christmas.