NowayPedro

NowayPedro

Active Member
Evening all

My electric fuel pump won’t stop making the priming noise when I turn on the ignition and causes the the twin SU’s to both drip fuel out of the overflow pipes and onto the ground. It continues when the engine runs too.
It’s a 3.5 V8 fitted in my series 3.

The fuel pump is a retro fit (by previous owner) and is a little silver/chrome coloured cylindrical thing accessed under the access hole under the drivers seat.

Any ideas how I can stop it over pumping or why it’s doing it?


Thanks a lot

P.
 
Photo of the pump may help.
Most pumps prime then stop/start(called interrupter pumps) and speed up when more fuel is needed.
If it’s pushing fuel past the overflow pipes you need to check your floats as they are probally worn. These have rubber on the tips
 
The electric pump on my 101 V8 runs constantly there is no cut off thats why there is a return to tank as it's to stop fuel heating up as well...your problem is either in the carbs or return pipe blocked...
 
It's a redtop fuel pump (just checked) and the overflow pipes don't actually go to the tank on mine. They just dangle out the bottom of the engine bay.
20230720_182740.jpg
 
If it was just one them I could understand that but as it's both it does seem a bit too much of a coincidence that both floats aren't working properly no? Although possible I guess.
 
I have a feeling the red top pump might be one that provides too much pressure. Do they have adjustable regulators on them?
 
NowayPedro said:
I have a feeling the red top pump might be one that provides too much pressure. Do they have adjustable regulators on them?
Click to expand...
You can’t adjust the pressure in these. Most are upto 14psi.
When the pump is ticking squash the flow pipe & if it stops that’s what’s meant to happen.
You can get pressure regulators for these but are expensive
 
OK thanks. So if I squash the overflow pipes and the pump stops priming it would suggest that the pump is too powerful for the su's.

I might see if these overflow pipes are actually meant to return to the tank somewhere/somehow.

Tomorrow is another day!
 
NowayPedro said:
OK thanks. So if I squash the overflow pipes and the pump stops priming it would suggest that the pump is too powerful for the su's.

I might see if these overflow pipes are actually meant to return to the tank somewhere/somehow.

Tomorrow is another day!
Click to expand...
No squash the feed to the carbs.
If you block up the over flows this will dump the petrol direct into the carbs & flood the engine

You should have a link pipe between the 2 carbs and the rerun will be on this. It has a restriction in it so if it’s not fitted may cause the pump to run all the time
 
Ah yes I see. I did have a look on the link pipe a couple days ago but I'll look again.

Thanks very much to you and all.

P.
 
I use one of those pumps if its a red top put out up to 32gph at about 15psi on my old Cortina rally car they must be used with a pressure regulator normally regulated down to 4psi the one i have is a filterking, the pump normally run fast to prim the carbs then slow down to a slow tick, i can hear when the float chambers are full :vb-biggrin:, and when i have run out of fuel:(
 
NowayPedro said:
It's a redtop fuel pump (just checked) and the overflow pipes don't actually go to the tank on mine. They just dangle out the bottom of the engine bay. View attachment 293258
Click to expand...
If it's a red top that is a facet pump rated for competion use rated for engines over 200 BHP...they do not have a pressure regulation they just pump...you need a silver top that pumps at 4.5psi with a return to the tank...I take it that the engine is retrofit to a petrol non V8 tank...strip carbs and check needle valves and floats also pics of carbs set up will help I spent hours sorting bodges on my 101 when sorting the fuel system...
 
Yes, it’s a v8 from a r.r. Classic 1983. Original series 3 petrol tank.
Can I keep this pump and work out a way to return the overflow back to the tank?
 
Cheers. So I can fit a regulator to work with a red top? Wasn't sure they could be regulated as per previous post.
 
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