Weber Monopoint Injection System

[racehead]

Thank you Mr.Guy for helping me out posting these pictures. I have a Citroen AX 1124cc and it has the monopoint fuel injection. There a lot of them with the Bosch monopoint but mine is from Weber. Do anybody has one like mine? My major concern is to modify it. My head was ported it flow much better then before, now there is the need to ajust the fuel mixture. I have seen people put in sereis a resistor with the water temperature so the computer thinks that the engine is cold and makes the mixture rich. Any help will be greatly apreciated.

[Guy Croft]

Why not try what I used to do with Bosch L Jetronic on Fiat units - increase the injection line pressure a bit. I used to increase by 3psi on a 45 psi line which is about 7%.

I assume this system has a fuel pressure regulator as standard fitment and it may not be possible to adjust it.

To do what I suggest you must buy and fit a fuel pressure gauge in the feed line to the injector and measure what psi it is now at idle and then fit a Webcon rising-rate (adjustable) fuel pressure regulator in place of the original and calibrate it to the present pressure + 3psi.

Prove out by driving and plug checks under load at various speeds. The big danger is it runs lean and the plugs will be white and blistered. You can keep increasing the pressure but I guess there must be a limit.

That is the best thing I can recommend, short of changing the whole package,

G

[WhizzMan]

Uprating the fuel pressure does not mean you will get linear increase in fuel. Also, linearity on fuel increase over load/injector time isn't there. The added fuel will require ignition timing changes as well, to optimally get all the power out. You will probably get less precision with tweaking the fuel pressure than you would get out of putting a carb on and swapping jets on that.

You could try and remap the computer, but since it's a monopoint, you would probably gain more by putting in a multipoint that is easily programmable, like a VEMS or a MegaSquirt. Mind you, both will probably have no problem controlling your current monopoint setup as well. If you are looking at megasquirt, a spinoff called KDFi is actually nice to consider. For little more than the megasquirt parts will cost you, you will get a pre-assembled smaller circuit board that has (optionally) a wideband controller on it as well, plus features to control spark coils and all that.