The Triumph Dolomite Club - Discussion Forum

Last time I went out in my 1850 auto a couple of weeks ago.One of the carbs was flooding so I ordered a overhaul kit from Burlin. I have now overhauled the two carbs, fitting a new needle valve etc.when turning on the ignition the electric pump starts to fill the carbs and fuel escapes out of the upper orifice, when engine starts the leak stops. Now I'm thinking maybe the electric pump I installed last year has possibly too much pressure what are your theories please.And if you agree that might be the problem how much pressure should the pump put out to a pair of Stromberg Carbs
Tomorrow I am going to check the float level just to make sure that is correct.Alan

Too much pressure from the pump (your theory) would be my first guess.
Aren't the mechanical pumps around 3 to 6 psi?

I have always understood not to exceed 3 psi, and 2 psi is better. Higher pressure will overwhelm the needle valves. What pump have you got, make and model. It should be easy to find the output pressure on the internet. If it's over 3 psi get a fuel pressure regulator.

alvera wrote: ↑Fri Mar 25, 2022 6:36 pm Last time I went out in my 1850 auto a couple of weeks ago.One of the carbs was flooding so I ordered a overhaul kit from Burlin. I have now overhauled the two carbs, fitting a new needle valve etc.when turning on the ignition the electric pump starts to fill the carbs and fuel escapes out of the upper orifice, when engine starts the leak stops. Now I'm thinking maybe the electric pump I installed last year has possibly too much pressure what are your theories please.And if you agree that might be the problem how much pressure should the pump put out to a pair of Stromberg Carbs
Tomorrow I am going to check the float level just to make sure that is correct.Alan

What pump is fitted? Many electric pumps are indeed too high a pressure, 2psi is more than enough, anything over 3 will potentially cause issues.
Simple answer is to try a pressure regulator. I had a Sytec one on a car, that worked well and wasn't overly expensive.

I have ordered a pressure regulator just to be safe, I'll look up the name of the pump and then I can see what pressure it should be putting out.
Thanks for your suggestions I will come back to you next week when the pressure regulator comes .Alan

Modern lower pressure pumps are easily available, I run a Facet Posi-Flow 60104 on mine which is rated at 1.5 - 4.0 psi and the SU's are fine with that.

dursley92 wrote: ↑Mon Mar 28, 2022 4:36 pm Modern lower pressure pumps are easily available, I run a Facet Posi-Flow 60104 on mine which is rated at 1.5 - 4.0 psi and the SU's are fine with that.

When all is perfectly fine the float needles wild hold 4.0 PSI. When there's some wear the troubles come at idle. Because the little amount of fuel is taken out of the float chambers at idle the float level does rise by the over pressure causing a richer mixture. Turning the jets up is the most often what is being done at too rich at idle but then you are in shortage of fuel when driving. People start adjusting a few day's and it won't work out obviously. Too high pressure isn't alway's related to electrical fuel pumps but also the current reproduction mechanical pumps. Some can have 0,6 bar, 9 psi.

Jeroen

cliftyhanger wrote: ↑Fri Mar 25, 2022 8:19 pm

alvera wrote: ↑Fri Mar 25, 2022 6:36 pm Last time I went out in my 1850 auto a couple of weeks ago.One of the carbs was flooding so I ordered a overhaul kit from Burlin. I have now overhauled the two carbs, fitting a new needle valve etc.when turning on the ignition the electric pump starts to fill the carbs and fuel escapes out of the upper orifice, when engine starts the leak stops. Now I'm thinking maybe the electric pump I installed last year has possibly too much pressure what are your theories please.And if you agree that might be the problem how much pressure should the pump put out to a pair of Stromberg Carbs
Tomorrow I am going to check the float level just to make sure that is correct.Alan

What pump is fitted? Many electric pumps are indeed too high a pressure, 2psi is more than enough, anything over 3 will potentially cause issues.
Simple answer is to try a pressure regulator. I had a Sytec one on a car, that worked well and wasn't overly expensive.

I have a Huco pump which is rated with a pressure of 0.1.5 bar. so seems to be fine.Today I took the float bowl of and discovered the "New" needle valve was sticking so put the old one in after checking the operation and the leak has stopped so the pressure regulator won't be necessary it seems.
the next problem is on starting up the car it is idling at 13000 rpm and I can't seem to lower the revs. When I split the carbs I undid a small nut and bolt on the throttle bar to separate the carbs and I wonder if I have inadvertently re-coupled it back in the wrong place ( is this a possibility ?) I have not messed with any other settings other than the jets( As I had to replace one which was seized.
Very helpful on this forum and I am sure you will help me as I don't really know what I am doing but I am learning through you expensive knowledge. Alan

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the next problem is on starting up the car it is idling at 13000 rpm and I can't seem to lower the revs. When I split the carbs I undid a small nut and bolt on the throttle bar to separate the carbs and I wonder if I have inadvertently re-coupled it back in the wrong place ( is this a possibility ?) I have not messed with any other settings other than the jets( As I had to replace one which was seized.
Very helpful on this forum and I am sure you will help me as I don't really know what I am doing but I am learning through you expensive knowledge. Alan
[/quote]

Any time you have had the carbs apart like you have its always best to re-check the basics like the mixtures on both and the balance between them.

13,000 rpm Let's divide that by 10.

The thought that springs to my mind is that one or both of the throttle butterflies is being held very slightly open. It doesn't take much to really make the engine race. Slacken the link between the carbs and see if the idle settles down.

Bumpa wrote: ↑Wed Mar 30, 2022 5:50 pm 13,000 rpm Let's divide that by 10.

The thought that springs to my mind is that one or both of the throttle butterflies is being held very slightly open. It doesn't take much to really make the engine race. Slacken the link between the carbs and see if the idle settles down.

Yes that was my thought I'll try undoing the little nuts and bolts tomorrow and hope for the best thanks Alan