Fuel System Woes

Lord Rover

Lord Rover

New Member
I have just had the old girl mot'd but the fuel pump died on it.

So my mechanic fitted an electrical fuel pump to it bypassing the old mechanical one.

Now the problem i have is after a couple of miles it slows down and conks out.


The Fuel filter never seems to completly fill and if the ignition is off the pump tries to fill the system and petrol pours down from the front off the fan cowling and down on the floor at a rate of knotts.

any ideas ???
 
I would disconnect that quick if I were you. I mean disconnect the wiring - battery first :? ( I hope the battery is in the boot on your car)

Where has he got it wired into?

And how does the petrol get to the front of the fan cowling? Can you see where it is leaking from?
 
Hi

It seems that the garage has wired your pump incorrectly so it runs when the ignition is off and cuts out when the ignition is turned on (hence running out of fuel in the carbs when running).(may be a poorly sourced earth). You need to start again & have a positive feed to the fuel pump only when the ignition is in position 2 (warning lights on dash illuminated) and pump earthed straight to the body/chassis. Ideally this needs to be fed through a relay and an "inertia switch" (cuts power to the pump in the event of a crash/impact). These can be sourced cheaply from E bay.
The fuel running out from near the front cowling is probably from the overflow pipes from the carbs, which would indicate that one or both of them are flooding, due to sticking floats or that the fuel pump is from an injection fuel system, which would be far too high a pressure for the system to cope with.
I hope this helps you.
Glen.
 
Beg your pardon i made a mistake,

i ment when the ignition is on not off

the fuel pump is a equivelent to a facet one made by lucas and has a cut off built into it when the system reaces pressure
 
Is assume your engine running the twin SU carburettors?

If so, that system incorporates a "spill return" whereby excess fuel is returned to the tank once the carb float chambers are filled.

The type of electric fuel pump that should be fitted in such a case is one that runs constantly once switched on. The reason fuel is pouring down the front of the engine with the pump running is that either one or both of the floats within either or both of the carburettors has failed. The floats are plastic, and overtime they can fill with fuel. When this occurs, the float chambers will overfill with fuel, the excess will be directed via the overflow pipes off the carburettors, exiting onto the road.

As fuel is running all over the front of your engine, that suggests that the overflow pipes are damaged. Inspect the pipes and replace them as necessary. Of course this is only a safety measure, as you don't want fuel running over a hot engine. The cause remains the float or possibly floats within the carburetors. Either one or both will require replacement. Ideally do both so as to ensure a satisfactory outcome.

Ron.
 
Beg to differ Ron. Not all cars have the spill return system, only the later ones. But, yes, that's a 100% diagnosis of float problems on the carbs!

Chris
 
Hello Chris,

Thanks for correcting me on that one...! So don't the series 1 cars incorporate a spill return system? If not, how does the system work given that a mechanical fuel pump is used?

Ron.
 
It could also be that the pressure of temporary electric fuel pump fitted is too powerful and is blowing the float chamber needles open to the point of overflowing,which will lead to the engine flooding,overfuelling and conking out!!
You need to fit a pump which gives a good steady flow instead of a high pressure!
Ive got a std Mini electric pump wired into my pipework so that if I get fuel vapourisation,I can turn it on and get the fuel flowing again.
It doesnt like being on all the time,and will overheat as its used to a little Mini not a twin carb V8!!
I have just bought a SD1 V8 electric pump,that is used to V8's and constant running and will be fitting that when it arrives!
I have also just run a new fuel feed pipe from the tap,via the mini pump,then to the manual pump,away from the heat of the engine in an attempt to cure vapourisation problems when hot!
 
Hi - def sounds like a float bowl issue or needle valve. I had a similar problem on Saturday (petrol gushing out of the overflow pipe). The carb was stripped and it transpired to be a hornet !! of all things that was stuck in the fuel intake pipe by the carb. A part of its shell had been drawn in to the carb and had jammed the needle valve open !! how it got in there and passed the fuel filter god knows. The most bazare breakdown I have ever experienced. wierd.
 
Hi.
no all the filters are in place (and new). I can only assume that the wasp crawled into the fuel intake pipe by the carb when it was disconnected during restoration works.
 
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