Fuelling issue

[Groundes-Peace]

On attempting to start my engine today there appears to be no fuel getting to the carbs, despite the engine cranking over well.
If the mechanical fuel pump is beginning to fail, will it be unable to deliver enough pressure at cranking speed to get fuel to the carbs?
A month ago I had a problem when I had to run the car at idle for 3 minutes waiting at a service station and the engine cut out. It would not restart for 5 minutes, then seemed OK.
Today when I tried to start for the first time in 2 weeks the car ran for 15 seconds then cut out and refused to restart.
When left for 20 minutes it still refused to start.
Thoughts?

[Rustinmotion]

Originally Posted by Groundes-Peace

On attempting to start my engine today there appears to be no fuel getting to the carbs, despite the engine cranking over well.
If the mechanical fuel pump is beginning to fail, will it be unable to deliver enough pressure at cranking speed to get fuel to the carbs?
A month ago I had a problem when I had to run the car at idle for 3 minutes waiting at a service station and the engine cut out. It would not restart for 5 minutes, then seemed OK.
Today when I tried to start for the first time in 2 weeks the car ran for 15 seconds then cut out and refused to restart.
When left for 20 minutes it still refused to start.
Thoughts?

If you take the fuel line and feed it into a bottle do you get petrol when you crank the engine? Running for a short while kind of points to you running on what’s in the fuel bowls so a quick check as above will let you check this, if nothing comes out carefully suck fuel to prime the pump it might work once the pump is primed but it’s likely the pump is failing or you have a blockage

[142 Guy]

Your description would be consistent with a fuel delivery issue; but, that does not mean that it is a fuel delivery issue. Drop a float bowl to confirm that it is dry. If the float bowl has petrol in it and it will not start it is time to look someplace else. If it is dry then the pump would be the prime suspect although checking the fuel lines to confirm that they have not been damaged would be a good plan. I assume that you have confirmed that the fuel level is above the suction tube level? Another possibility on these ageing vehicles is that the suction tube has fallen off and is now rattling around in the bottom of the tank. However, start with the fuel pump first because a failed suction tube is going to be a major repair effort.

If the procedure for diagnosing a fuel pump failure is not self-evident, use Google with the search term 'Checking a Mechanical Fuel Pump'. It will get you some suitable hits to help with your diagnosis. Depending on which mechanical fuel pump you have and the type of failure there are rebuild options. Rebuilding or outright replacement is your decision.

[Groundes-Peace]

Thanks for replies.
I have dropped the bowls in the carbs and they had almost no fuel there.
I have yet to disconnected the fuel line to see if any fuel comes through from the pump when the engine is cranked. I suspect there won't be.
All the fuel lines were replaced a month ago and the car performed perfectly.
The fuel pump is my main suspect!
Last year, whilst touring I had no alternative but to fill up with E10 on a number of occasions. I now wonder if this could have accelerated a problem with an ageing fuel pump...?
Has anyone a view on the problem if it turns out to be the pump, i.e. try to overhaul or replace?

[Rustinmotion]

Originally Posted by Groundes-Peace

Thanks for replies.
I have dropped the bowls in the carbs and they had almost no fuel there.
I have yet to disconnected the fuel line to see if any fuel comes through from the pump when the engine is cranked. I suspect there won't be.
All the fuel lines were replaced a month ago and the car performed perfectly.
The fuel pump is my main suspect!
Last year, whilst touring I had no alternative but to fill up with E10 on a number of occasions. I now wonder if this could have accelerated a problem with an ageing fuel pump...?
Has anyone a view on the problem if it turns out to be the pump, i.e. try to overhaul or replace?

Non glass bowl pumps are only £34 I’d say not worth the trouble to refurb

[142 Guy]

I am running D jet with an electric fuel pump so I can't advise on the refurbish versus replace question. From prior experience with a friend's Amazon I do know that there can be a question of the correct spacer between the pump body and the engine block. I don't know whether this is a model year specific problem or a pump brand specific problem. The spacer is thicker versus thinner for different pumps and if you get it wrong you will break your brand new pump So, if you elect to replace the pump just make sure that you have the correct spacer.

That is the sum total of my B18 / B20 mechanical fuel pump knowledge.

[Othen]

Originally Posted by Groundes-Peace

Thanks for replies.
I have dropped the bowls in the carbs and they had almost no fuel there.
I have yet to disconnected the fuel line to see if any fuel comes through from the pump when the engine is cranked. I suspect there won't be.
All the fuel lines were replaced a month ago and the car performed perfectly.
The fuel pump is my main suspect!
Last year, whilst touring I had no alternative but to fill up with E10 on a number of occasions. I now wonder if this could have accelerated a problem with an ageing fuel pump...?
Has anyone a view on the problem if it turns out to be the pump, i.e. try to overhaul or replace?

I use E10 all the time in GAM and have had no problems, it runs very well.

Bookhouse Volvo sells a rebuild kit for the jam jar type pumps for about £30 that is pretty simple to fit (a new diaphragm, a valve and a few gaskets), without looking at it I'd say that would be the way to go; the jam jar fuel pumps are really simple and should respond to some new bits of rubber. The first thing to do would be to test the pump output though, that will only take a few minutes and will make sure you don't go on a wild goose chase.

Early on in GAM's ownership I had an issue with fuel starvation caused by the inline fuel filter being fitted backwards, like this:



I got rid of it (fitted a new rubber pipe) and have not had a problem since.



This does sound like a fuel starvation issue, but I'd suggest you don't just start throwing new parts at it. Test the pump output first, then work out what is wrong by a process of elimination - only then, if you need to, get some parts to fix it.

Good fortune,

Alan

[Groundes-Peace]

Thanks for the various thoughts on how to resolve my fuelling issue. All good.
It was useful to link a length of fuelling line directly from a filler can and funnel to the fuel pump. This proved my pump is working correctly, and the fuel line from the pump to the carbs is fine, as my car started easily and would have carried on running to the fuel was exhausted.
My problem boils down to an obstruction somewhere between the tank and the pump. I tried using an airline to blow air from the pump connection of the fuel hose back to the vented tank. I am now wondering if this might have been a negative as it could stir up any sludge in the bottom of the tank by aerating it; I hope not! But the blockage is still there.
My car has a replacement fuel tank which is less than 10 years old.
Has anyone got any short-cut remedies, to avoid the need to remove the fuel tank and flush?

[142 Guy]

Originally Posted by Groundes-Peace

It was useful to link a length of fuelling line directly from a filler can and funnel to the fuel pump.

When you did this test, did you have the funnel at a level at or above the carburettor bowls? If so, it might have been the static head of the fuel in the funnel causing the fuel to flow through the pump to the carbs. This will occur even with a dead pump.

Fill a small container with fuel, set it on the ground under the engine. Prime the inlet of the pump with some fuel and then run that hose from the fuel pump into the ground level container. Now crank the engine and see if the pump draws fuel up from the ground level container. If it doesn't draw, try raising the level of the container a bit (up to tank level). If the pump will not draw fuel you probably do have a pump problem. If the pump does draw fuel then you do have a fuel line / tank problem of some kind.

Before removing the tank, inspect the fuel line for breaks. You could be sucking air rather than fuel!

[Groundes-Peace]

Thank you for the latest post from 142Guy. That is an interesting definitive test to undertake. Maybe I was to hasty to give the pump the all clear.
I will try this ultimate test.
My feeling is that the pump is OK.
I have a clear plastic filter in the piping before fuel gets to the pump. It has negligee fuel in it despite me ensuring the tank has sufficient fuel and the rubber fuel hose being renewed a month ago and all being fine deriving over 40 miles since then....
I will check more tomorrow.
Thanks again.