27 replies to this topic

[eshorer]

My 1967 Austin Estate (wagon) is cutting out, like it's not getting fuel, but only on the freeway going about 50 mph. On city streets in stop and go traffic it runs fine. This was happening once in awhile, like every 10th time I took it out, but recently it's happening after only a few miles of steady freeway driving at 50 mph. It's running a 997 with a single SU carb, and everything seems fine with the carb, and the fuel filter is getting fuel. Does this sound like a fuel pump problem? 

[Spider]

I'd start by checking the fuel pump pressure and delivery rate. It does ring of a fuel pump issue to me.

[slidehammer]

I had a similar issue years ago with an MG Metro which used the A series engine with a mechanical fuel pump. That would cut out only on long hills, where you are using more fuel to maintain momentum. That turned out to be the fuel pump failing to deliver enough fuel. So I agree with Spider start with the fuel pump.

[Ethel]

Carb & tank vents, along with the tank outlet strainer are also possibilities that are quick & free to eliminate.

[Lplus]

Carb & tank vents, along with the tank outlet strainer are also possibilities that are quick & free to eliminate.

Estates don't have a tank vent, the cap has to be of the vented type.  Pickup strainer clogging with dirt/rust/etc is a distinct possibility

[Ethel]

Oops, didn't register it was an estate. Easy to replace the cap with a loose cover.

[Aly-g]

sound like something in the fuel tank that is being drawn to the fuel outlet on a longish run without stops, when town driving the fuel is being sloshed about and the item blocking the fuel pipe moves, once had this problem with a truck I used to drive , in my case it was a newspaper that was found in the tank ! might be worth a look with an endoscope or some other means, let us all know when and if you find the problem.

 

Allan

[Aly-g]

Just another thought, could be any rubber fuel hose connections you have could be collapsing on the inside through age, worth checking out.

 

Allan 

[eshorer]

Just another thought, could be any rubber fuel hose connections you have could be collapsing on the inside through age, worth checking out.

 

Allan 

Hose to the fuel filter and then to carb are new. Brass fitting had "vibrated" out so I thought that was the problem, but after tapping it back in with hammer it's definitely staying in place, so it's neither of those.  

[Designer]

Hi

 

Question

 

If it is the tank outlet strainer what is the solution to changing it. New tank or cutting out and removing/replace then rewelding?

 

Paddy

[Lplus]

Hi

 

Question

 

If it is the tank outlet strainer what is the solution to changing it. New tank or cutting out and removing/replace then rewelding?

 

Paddy

If the strainer can't be cleared by blowing/washing back through the outlet and rinsing out the tank, then a new tank is probably the best solution.  The cost of decontaminating, cutting open, replacing strainer then rewelding and testing would far outweigh the cost of a tank - unless you happen to be a very good and careful welder.

[Ethel]

I was going to suggest punching the strainer through the fuel outlet, but remembered it's an estate. You could likely generate some serious pressure though, with the threaded union. I've fabbed an extra connection via the fuel gauge opening - but we could be talking about solutions to a problem that doesn't exist.

 

I'd likely start by replacing the filler cap with something that will definitely vent and give the carb's float chamber the once over. Check the float pivot & valve seat aren't worn - blow the vent drilling in the lid with an airline, or lever the little steel cover off. 

[eshorer]

One friend thinks it may be the wrong needle. It's a 997 Cooper engine (NOT 998) running a single SU HS2 1.25" carb with an EB needle. The online charts I've found don't show a single carb setup on a 997 Cooper engine, and with the twin carbs they show an GZ needle for that engine. Could that make a difference related to the original problem?

[eshorer]

Crossing something else off the list: I took it out WITHOUT a gas cap and it did the same sputtering at 50MPH. So it's not a venting problem with the unvented cap! Also, if this gives any further diagnostic help: Again, on the streets and freeway below 50MPH it's fine, accelerating as good as ever. After a few miles at 50MPH on the freeway it does its sputtering, I lift off the pedal, it seems to have fuel again, and when I try to get it to go faster than 50MPH it does the same sputtering. So that seems to be my "redline" and I can't make it go faster than that.

The search goes on...

[Clip]

Mine did exactly the same thing. Replaced with a new square Facet electric fuel pump which helped a little. Changed to Fuelmiser which increased flow by heaps but not pressure (did the flow/timing in a 1 litre container test) and never had a problem again, even at 90mph.