Fuel Pump & Pipe Problem?

[D Murton]

Sorry if this goes on a bit.

The PO of my 4A had fitted an inline fuel filter close to the carb inlet mounted between two short lenghts of stainless braid covered hose. This was not well done and the pipe from the pump loops over the top rad hose and down to the carbs.

One of these short pipes had started to leak and when I took it off it completely disintegrated..

Both the hoses were replaced and a new filter fitted. The filter was filled with fuel prior tn installation.

Stated up & left the car running to check for leaks only to watch the filter slowly empty.

Refilled filter - same result.

As I had a fuel pump repair kit I decided to take the top off the fuel pump & check the valves etc.

With the top removed the diaphragm looks OK but the valves are not retaind by a plate but appear to be pressed into the casting.

I checked the valves by blowing through the ports and while there is a little leakage it didn't seem significant.

As I didnt want to damage the pump by trying to prise the valves out it was all reassembled and the inline filter primed.

Car srarted, glass bowl filter filled quickly but again the inline filter slowly emptied.

The pump is obviously delivering fuel but I assume not enough.

Now to the questions

 

Can I replace the pump valves?

 

Should I consider an electric pump & if so which one and is a pressure regulator required?

 

Any other ideas welcome.

 

Thanks in advance

 

Dave

[Don Elliott]

1. Remove the fuel filter up near the carbs and see what happens. These often get air in them and cause problems. Originally, TRs didn't have these. Maybe you don't need it and maybe you don't want to have it cause a problem.

 

2. Clean out the screen filter in the glass bowl and also clean the glass bowl below the fuel pump, reinstall it and see what happens.

 

3. With the upper hose off, pull the trigger on the bottom of the fuel pump and see if it manually pumps fuel up to the filters.

 

Let us know what you find.

[D Murton]

1. Remove the fuel filter up near the carbs and see what happens. These often get air in them and cause problems. Originally, TRs didn't have these. Maybe you don't need it and maybe you don't want to have it cause a problem.

 

2. Clean out the screen filter in the glass bowl and also clean the glass bowl below the fuel pump, reinstall it and see what happens.

 

3. With the upper hose off, pull the trigger on the bottom of the fuel pump and see if it manually pumps fuel up to the filters.

 

Let us know what you find.

 

Hi Don

 

I Had considered taking the filter out but thought that ay least for the time being P could see that the carbs were taking more fuel than the pump was pusging through.

 

The pump does not have the priming lever. I guess its a pattern pump.

 

I will either turn the engine over by hand or take the pump off the block and work the lever which contacts the camshaft.

 

Dave

[TR4aStu]

Hello Dave

A similar problem we had on a Scimitar SE5 was that it was fitted with a pattern pump that seemed to be working fine when you tried it by hand but it would not run the car correctly. It turned out that the operating arm that runs off the cam was in a different postition and not being moved through its full range. Just a thought.

Stuart

[Dale Moore]

Just a thought Dave, but are you sure the pipe between the filter and the carbs is not blocked. maybe with the bits of rubber from the old pipe. could have blocked the needle valves in the SUs It could be that the pipe is just being pressurized, giving the impresion of no flow from the pump, seems a coincidence the pump fails at the same time you replace the pipe. I know sods law, etc

 

Regards

Dale

[D Murton]

Thanks for the replies. I wasnt able to investigate much yesterday ( MotoGP & family comitments).

 

The carbs were checked & cleaned after the pipe disintegrated so I'm fairly sure the they are OK

 

I took the plugs out, took the filter out & fitted a pipe leading into a can & spun the engine over on the starter.

 

The fuel pump appears to give plenty of flow but the pressure seems very low. The flow can be stopped by light finger pressure over the end of the pipe.

 

I'm a bit concerned that the pump valves can't be replaced and I think the next step is a rebuildable pump if such things are available these days.

 

Dave

[jonlar]

Hi Dave, could well be some disturbed gunge blocking up somewhere along the line. I don't know it they're still available - but you used to be able to buy pump kits with a new diaphragm and valves. Keep an eye on oil leve, if level rises could be getting petrol into engine oil and sump.