Fuelling issue - air lock??

[Kentish]

Hi Folks;

I'm posting in here and not the MG forum as I'd like to get some opinions today

I've just replaced the fuel pump on the B and it's all wired correctly and the fuel lines are on the correct sides of the pump. The pump is pushing (not sucking ) up to the carburettors

But no fuel is getting up there and hence the car's not starting.

Any thoughts on how I can prime up the fuel line and pump?

I'm currently thinking of slipping off the fuel delivery pipe to the carbs and using a small funnel to pour petrol back down the fuel line to the pump.

Is this likely to work before I head off out for a can of petrol?

TIA



K

[flatfour1]

Yes that will work fine.

[Kentish]

flatfour1 said:

Yes that will work fine.

OK, thnaks

I was wondering whether it will as the air lock must be between the tank and the pump?

[Vidal Baboon]

Is it not pumping at all?

You'll need a hand with this-

You could squirt some fuel into the SUs while cranking- don't pour it in- as you'll end up hydrolocking your engine (=bad, almost as bad as bad AIDS)

Crank the engine over & let the pump do it's job.


If it's the pump thats at fault- just disconnect the fuel line- from the pump to carb & crank it over till it starts squirting out.


Hang on...don't MGB's have an elctric pump anyway? Is it clicking away?

[Kentish]

Thanks.

Yes, it's clicking away nicely and I took the fuel delivery pipe of the SU carbs and I can feel air being pushed out so the pump is doing it's job and I even took the pump out again to double check I had the the connectors on the correct sides of the pump and that all appears to be fine:-

TANK -> PUMP -> CARBS.

Wiring is fine as it only works when wired correctly and will not reverse flow with reversed polarity.

Edited by Kentish on Saturday 13th June 14:42

[Vidal Baboon]

Kentish said:

Thanks.

Yes, it's clicking away nicely and I took the fuel delivery pipe of the SU carbs and I can feel air being pushed out so the pump is doing it's job and I even took the pump out again to double check I had the the connectors on the correct sides of the pump and that all appears to be fine:-

TANK -> PUMP -> CARBS.

Wiring is fine as it only works when wired correctly and will not reverse flow with reversed polarity.

Edited by Kentish on Saturday 13th June 14:42

In that case, if it was me, I'd just pull the pipe off the carb- turn the ignition on till it starts squirting out the end
(the pump shuts off when it reaches a predetermined pressure does'nt it?)

Then put the pipe back on the carb. Hey presto, should start!

Unless you've managed to burn the whole street down with your DIY antics

Edited by Vidal Baboon on Saturday 13th June 14:47

[Kentish]

Vidal Baboon said:

Kentish said:

Thanks.

Yes, it's clicking away nicely and I took the fuel delivery pipe of the SU carbs and I can feel air being pushed out so the pump is doing it's job and I even took the pump out again to double check I had the the connectors on the correct sides of the pump and that all appears to be fine:-

TANK -> PUMP -> CARBS.

Wiring is fine as it only works when wired correctly and will not reverse flow with reversed polarity.

Edited by Kentish on Saturday 13th June 14:42

In that case, if it was me, I'd just pull the pipe off the carb- turn the ignition on till it starts squirting out the end
(the pump shuts off when it reaches a predetermined pressure does'nt it?)

Then put the pipe back on the carb. Hey presto, should start!

Unless you've managed to burn the whole street down with your DIY antics

Edited by Vidal Baboon on Saturday 13th June 14:47

Well, that's the problem you see - I have taken the delivery pipe off the carbs and waited with the fuel pump ticking away for about 10 mins and no fuel has reach the disconnected pipe at the carbs.

There has got to be an air lock somewhere?

I'm also reluctant to leave the fuel pump running dry for too long.

Edited by Kentish on Saturday 13th June 14:58

[Kentish]

There is a quarter of a tank of fuel BTW

[Vidal Baboon]

Oh, pipe not kinked anywhere along the body?

Fuel is going into the pump?
IIRC the pump is fed by a normal 8mm fuel pipe connected to the bottom of the tank?

Is fuel draining from the tank into the pump? Take pipe off & leave to hang down- it should drip out.

Did you have to take any pipe stops out before fitting the pump?
(Like little red plastic bungs stopping dirt getting into it whilst in storage?)

Edited by Vidal Baboon on Saturday 13th June 15:06

[Kentish]

Vidal Baboon said:

Oh, pipe not kinked anywhere along the body?

Fuel is going into the pump?
IIRC the pump is fed by a normal 8mm fuel pipe connected to the bottom of the tank?

Is fuel draining from the tank into the pump? Take pipe off & leave to hang down- it should drip out.

Did you have to take any pipe stops out before fitting the pump?
(Like little red plastic bungs stopping dirt getting into it whilst in storage?)

Edited by Vidal Baboon on Saturday 13th June 15:06

I'm not sure whether fuel is going into the pump. It sounds like it is running dry to me.

The pump is blowing air through to the carbs though as I can feel it coming out of the pipe where it is disconnected at the carbs.

I've sent Mrs K out for a can of petrol now and I will back fill the fuel line at the carb end to try and prime the pump.


Yes, plastic bungs removed

Edited by Kentish on Saturday 13th June 15:19

[Vidal Baboon]

Kentish said:

Vidal Baboon said:

Oh, pipe not kinked anywhere along the body?

Fuel is going into the pump?
IIRC the pump is fed by a normal 8mm fuel pipe connected to the bottom of the tank?

Is fuel draining from the tank into the pump? Take pipe off & leave to hang down- it should drip out.

Did you have to take any pipe stops out before fitting the pump?
(Like little red plastic bungs stopping dirt getting into it whilst in storage?)

Edited by Vidal Baboon on Saturday 13th June 15:06

I'm not sure whether fuel is going into the pump. It sounds like it is running dry to me.

The pump is blowing air through to the carbs though as I can feel it coming out of the pipe where it is disconnected at the carbs.

I've sent Mrs K out for a can of petrol now and I will back fill the fuel line at the carb end to try and prime the pump.

Try pumping from your fuel can (run a pipe into the jerry can)- if that works you can rule out everyting bar the feed to the pump & the fuel tank.

[Kentish]

Vidal Baboon said:

Kentish said:

Vidal Baboon said:

Oh, pipe not kinked anywhere along the body?

Fuel is going into the pump?
IIRC the pump is fed by a normal 8mm fuel pipe connected to the bottom of the tank?

Is fuel draining from the tank into the pump? Take pipe off & leave to hang down- it should drip out.

Did you have to take any pipe stops out before fitting the pump?
(Like little red plastic bungs stopping dirt getting into it whilst in storage?)

Edited by Vidal Baboon on Saturday 13th June 15:06

I'm not sure whether fuel is going into the pump. It sounds like it is running dry to me.

The pump is blowing air through to the carbs though as I can feel it coming out of the pipe where it is disconnected at the carbs.

I've sent Mrs K out for a can of petrol now and I will back fill the fuel line at the carb end to try and prime the pump.

Try pumping from your fuel can (run a pipe into the jerry can)- if that works you can rule out everyting bar the feed to the pump & the fuel tank.

That may be tricky as the fuel pump has unions and a solid pipe and I don't have enough spare parts laying around to make up a flexi connection from the fuel can to the pump.

I could try pushing a piece of fuel hose into the pump supply side quite hard by hand and keeping it held in there whilst Mrs K switches on the ignition and then watched to see whether the filter fills with fuel up at the carb end.

I'll have a quick go at the back filling of the fuel line first to see whether I can prime the pump.

If that doesn't work I'll do as you suggest. Although the pump in a B is below the tank so the pump should never be starved of fuel (in theory), as long as there is fuel in the tank of course .....which there is currently

[Vidal Baboon]

Sounds dangerous

Does it look like this?


I'd try loosening the unions, & turn the ignition on, to see if anything seeps out- if it's wet on the tank side of the pump- you know it's getting some.

Is the pump clicking faster than usual- thats a sign it can be tring to pump air instead of fuel.

If you do try an pump from a jerry can- try not to get it in your eye- it stings like a bd!

Edited by Vidal Baboon on Saturday 13th June 15:36

[Kentish]

Right, that was a good diagnostic test!

I pushed a funnel inside the fuel delivery pipe at the carbs and filled the filter and fuel line with petrol and it reached the pump and pissed out all over the ground and that was on the tank to pump side of the pump.

So, I'll take it all apart again now and see what's going on with that connection

[Kentish]

Right; I filled up the fuel line back to the pump and no more leaks.
I've never known banjo connectors to require 2 fibre washers but this appeared to do the trick (one each side of the banjo). No more leaks!

I filled up the carb side of the fuel line after the filter to ensure the float chambers were full, all OK.

I re-connected the fuel lines around the fuel filter and pump, all OK.

Started car and it ran pretty much straight away as there was fuel in all the lines and it ran for a good 5 mins but I was watching the fuel filter and the level of fuel in it was below the inlet and outlet (horizontal filter) and as you might have guessed ....before long the car cut out due to insufficient fuel.

I took a long length of fuel hose and connected it to the outlet side of the in-line fuel filter and the other end I immersed in the bottle full of petrol I have been using to back fill the fuel line and then switched the pump on and let it run for a while, all the time it was blowing bubbles through the petrol in the bottle.

Looks like there is still an air leak on the inlet side of the pump, so I tightened the fuel banjo's into the fuel pump much tighter than I am comfortable with (since they go into plastic threads in the plastic fuel pump housing) and still I am getting air coming through and the car will not run.

The pump is the issue, cheap (£50) crap pump that you can't get a good seal on.

Looks like I'll be pushing the car back into the garage and returning the stupid pump to MGOC Spares for a refund

What a waste of a day!

Edited by Kentish on Saturday 13th June 17:16

[Kentish]

So, today it was both hands to the pump again

I received my replacement pump from MGOC Spares (a decent original SU pump this time) and I took the opportunity to order some new new fuel lines, one from the tank to the pump and one from the pump to the fuel line that leads to the engine bay.

I've only placed 3 orders with MGOC Spares so far and they've got it wrong 3 times!

They sent everything but didn't put the new fuel pipe from the tank to the pump in the parcel to me, despite me actually giving them all the part numbers. Can't anyone get anything right??

Anyway, I got the pump in and all new fittings and washers and the new piece of flexi pipe went in, the one that connects to the hard fuel line to the engine bay.

I fitted the vent pipes to the pump as these had been left off the old pump, cleaned the electrical terminals and did everything up nice and firmly, mounting the pump nice and securely in the bracket too.

All looked good; I backfilled the fuel line to prime the pump (in case it needed it) and that all looked good so I reconnected the fuel supply to the carbs and jumped in to fire her up.

A few turns on the starter and she sprang into life, ran for 3 mins and then spluttered to a halt.

I took off the hose at the carbs again & repeated the backfilling process and same again, ran for a few mins and stopped.

It was clearly using fuel in the fuel line and float chambers and then running dry.

I had already blown out all of the fuel lines with compressed air so I knew there were no blockages.

I began to suspect that there must be an issue with the fuel supply to the pump, could there be a pick up pipe inside the tank that has come off??

I decide to test for this by undoing the solid pipe from the tank (the one MGOC Spares neglected to send) and then fit some rubber fuel line over the end with a funnel connected at the other end - I then filled the funnel with fuel and looked for leaks before starting the car - well I didn't need to look far!

Fuel pee'd out everywhere from that pipe; it must have a crack in it and hence is sucking in air and no fuel.

Problem solved, unfortunately the sinlgle most important part is the one I don't have because they forgot it and I now have to wait until next week to hear that sweet little engine running again.

Oh well, at least I now know what the problem is - shame it has taken 3 weeks to sort it out though!

Thanks for all the help here and my thanks to Watford Classics who are sending me out a replacement for the broken fuel pipe. This is the second time I've ordered from them and they have been very good.

[GreenV8S]

Kentish said:

Fuel pee'd out everywhere from that pipe; it must have a crack in it and hence is sucking in air and no fuel.

If I've understood you then there's a leak between the tank and the pump, sure the tank will empty itself via the leak? Unless the leak is above the level of the tank, in which case I'd expect to have priming problems anyway unless the pump is designed to self-prime.

[Pigeon]

GreenV8S said:

Kentish said:

Fuel pee'd out everywhere from that pipe; it must have a crack in it and hence is sucking in air and no fuel.

If I've understood you then there's a leak between the tank and the pump, sure the tank will empty itself via the leak? Unless the leak is above the level of the tank, in which case I'd expect to have priming problems anyway unless the pump is designed to self-prime.

They are self-priming, but I'm having difficulty with "fuel peed out everywhere" followed by "there "must be" a crack". I'd figure a crack big enough to pee fuel everywhere would be big enough to see, and therefore to be able to say definitely "there is a crack", rather than inferring that there "must be" one. Sure it's not leaking from the temporary connections to the pipe and running all over the outside of it?

On a Morris Minor the tank breather is a cruddy arrangement in the filler cap; I don't know what the MGB has but I'd not be surprised if it's similar. If it gets blocked the car will run until the pump can no longer pull fuel against the vacuum created in the tank.

[Kentish]

I made a tight seal onto the piece of pipe I took off the tank, with a length of fuel hose with a funnel pushed hard into it so there was definitley no possibility of a fuel leak in my temporary connections.

I then poured some fuel in the funnel and down the rubber temporary hose and back down that piece of solid fuel pipe that runs from the tank to the pump to test that side of the pump and that was when the fuel poured out.

It was coming from up the solid piece of fuel line between the tank and pump (suction side of pump).

That piece of pipe is clipped into place quite high up and out of sight so you can't check it fully without removing it but since it poured down from up there and the pipe is not in its first flush of youth and looking at where it goes through the clips on the chassis, I'd say it has a crack in it.

This makes sense as the nett result would be as experienced, no fuel to the carbs because the suction side of the pump is sucking in air and not allowing the pick up of any fuel. Prior to doing this test on that section of pipe I had everything connected except the fuel supply pipe to the carbs (under the bonnet) which I dropped into a jar of petrol and I switched on the pump and all I got out of the pipe were air bubbles which proved their was a suction leak somewhere, I just couldn't find it for a while

It's just a shame that MGOCS omitted it from my order otherwise the wee beasty would be running by now.

[Kentish]

GreenV8S said:

Kentish said:

Fuel pee'd out everywhere from that pipe; it must have a crack in it and hence is sucking in air and no fuel.

If I've understood you then there's a leak between the tank and the pump, sure the tank will empty itself via the leak? Unless the leak is above the level of the tank, in which case I'd expect to have priming problems anyway unless the pump is designed to self-prime.

Hi Pete;

Yes spot on, the fuel pipe is slightly above the level of fuel in the tank which is handy as I have half a tank of fuel currently!

The pump should self prime but I've been giving it a hand by filling up the fuel line from the carbs back down to the pump before turning the car over.

I also had the car running on a temporary fuel supply local to the carbs just to make sure all was OK and she ran perfectly for a good 20 mins or so, so early on I ruled out any other issues unrelated to the back end of the car

I think once that solid fuel pipe from tank to pump is replaced I should be fine.

How's the Tiv these days?

Still miss mine!

Cheers,
Kevin