Fuel pressure regulator

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pasoalf
Posts: 72
Joined: Tue Feb 03, 2009 9:44 pm
model: 750 Paso
year: 1987
Location: Switzerland

Fuel pressure regulator

Post by pasoalf »

I've read in the TECH FAQ that a fuel pressure regulator would improve the the behaving of the Paso. I already got used to the "behaving" of the Weber Carbs (full open or closed it behaves O.K). But crusing to the city or first gear corners is still difficult beacause a sligth turn at the handbar makes a big effect.
Can anybody tell me wether its worth to invest some time with it, or has anybody exerience with it and can deliver some details? (Other carbs are no option for me)
Tnks
pasoalf
Paso 750/ 1987
Paso 906/ 1992
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ducapaso
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model: 750 Paso
year: 1988
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Re: Fuel pressure regulator

Post by ducapaso »

I have an hand made regulator installed, but I think it only helps to fill the float level after a long time standby...
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chi

Re: Fuel pressure regulator

Post by chi »

i would forget about the pressure regulator as there should be a return line to the tank which negates the need for a pressure regulator. the real problem lies with the voltage supply to the coils. if you do a voltage check at the coil supply you will find that the coils only get about 9 volts not 12 which means a huge drop in the voltage arriving at the spark plugs. thus leading to fouled plugs and substandard performance.a relay needs to be installed to deliver battery voltage to the coils. incidently the coils are where battery voltage is sensed which is why the battery can give problems with over charging
i have done this electrical mod and the difference is amazing. no more fouled plugs, no flat spot under 3000rpm, no more over charged battery and easier starting
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higgy
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Re: Fuel pressure regulator

Post by higgy »

chi wrote:i would forget about the pressure regulator as there should be a return line to the tank which negates the need for a pressure regulator. the real problem lies with the voltage supply to the coils. if you do a voltage check at the coil supply you will find that the coils only get about 9 volts not 12 which means a huge drop in the voltage arriving at the spark plugs. thus leading to fouled plugs and substandard performance.a relay needs to be installed to deliver battery voltage to the coils. incidently the coils are where battery voltage is sensed which is why the battery can give problems with over charging
i have done this electrical mod and the difference is amazing. no more fouled plugs, no flat spot under 3000rpm, no more over charged battery and easier starting

Oh Contra Mein Heir.
While the electrical mod is decidedly worth while,a return line does not negate the benefits of a fuel pressure regulator.
Holley makes a good one and there are several others. You need one in the 0 to 4psi range and measure the pressure at the carb and set to 3 psi.
Also check out the many threads here on setting up the Weber.
I'm kinda partial to the Weberology thread myself :choo: :thumbup: :thumbup:
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Mc tool
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model: 906 Paso
year: 1990
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Re: Fuel pressure regulator

Post by Mc tool »

I think that Chi raises a good point about the feed to the coils , the same should be done for the ignition module , and a decent earth fitted . I had all sorts of problems with mine ( see earlier posts ) untill I did this mod .I later found out that this is why the last owner sold it .I think the main issue is the main power supply wires are to small and fitting relays to the main organs is a good cure as long as there is a power feed direct from the main fuse to each relay . I mucked about with the lenght of the return line to get a suitable fuel pressure I have a rotory type pump and I just lenghtened the return line till I could hear the pump motor just starting to work a bit ..yeah yeah ,I can imagine what your thinking :wacko: but it worked :thumbup:
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JWilliam
Posts: 331
Joined: Wed Oct 06, 2004 12:00 am
model: 906 Paso
year: 1989
Location: Nottingham, UK

Re: Fuel pressure regulator

Post by JWilliam »

There are several basic changes that improve our Paso's.
Bauke's Relay bypass for the ignition unit - correct supply voltage to Digiplex & better ignition
Fuel Pump regulator - stops stalling at tickover
Up jet the accelerator pump - smoother throttle response
Check ignition coil impedance - too low and the Digiplex can fail

As has already been said there are many more but patience and a willingness to disassemble pays dividends.
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