jpitman

My WUR recently produced a high control pressure, giving me a lean mixture, poor response. There was high resistance at the inlet port. No visible crap on the inlet wire gauze filter. Flushed with carb cleaner , blew it out, back on, goes well.
Now a few weeks later the symptoms have come back, high control pressure again (70 vs 45 psi). WUR inlet plugged again. Cleared it the same way (getting ggod at this now), but dont want to go back there again (SWMBO is making rumbling noises). Dont know how to get the filter out.
Can anybody suggest a solvent that will really clean out any deposits in there, or tell me how to get the filter out please? Blow injector cleaner through it?
TIA,
jp 83 Euro S

Dennis Wilson

Try removing your screen and retest. If it is still high recheck your bypass/relief valve. if it is like my 78 there should be two o rings (one on each end). Make sure they haven't deteriorated and plugged the line from the valve to the WUR. BTDT.

Good luck.

Dennis

Jack in Malta

I have the same problem, although its the outlet that has the mesh filter isnt it as this is the return to the bottom of the head, pressure relief valve and ultimately return line to the fuel tank. Is this part really servicable as it appears the mesh element is not removeable

jpitman

Dennis,

What screen? Where? I cant get the inlet filter out of the WUR AT ALL!!
Jackin- the small filter (~8mm) is in the inlet line on mine, under the fitting the tube screws onto vertically. First time, I had control pressure of 65psi, opened the return line from WUR to distributor to check if it was blocked, NOTHING came out - this line comes off right side of WUR horizontally, goes down RH side of engine under spider (all looking into engine bay). Fuel flow rate is good, so no major blockages elsewhere I think.
thanks,
jp 83 Euro S

Jack in Malta

Did you open the WUR and remove the plate under this unit (held with 4 small screws.) and clean this out, I had dirt in this area once but in my case although I now have a good flow of fuel to and from the WUR I still have the same problem,, my car now only runs for some 30 seconds before the pressure goes high and the car will no longer pull at all. If I switch off for 2 - 3 seconds the car starts and works again for another 30 second. it ticks over all day, just cant drive it

jpitman

Jackin,
Watson diagnosis process - fit pressure gauge on inlet line to WUR ; with tap open, shows control pressure; with tap closed shows system pressure - both need checking. System should be 65-75psi- mine 75.
If control is high (should be 41-46psi, mine was 65+), crack open the return line at WUR a touch - if pressure now drops, the return line, or something downwind of it, is blocked/restricted. If not the actual pipe from WUR (disconnect other end, blow through), follow the line disconnecting fittings one by one until you find one that does NOT drop the pressure. The problem then lies one leg back from there.
Have you checked flow rate ~ 1.25L/30secs? CHecked return hose into top of tank for flowing ok? checked return pipe into tank is not blocked?
Yes, I opened up the WUR, removed all the bimetal strip stuff, opened up the regulator (small round thing with 4 small screws), cleaned it (no dirt or deposits visible). Fitted a new O ring (dropped pressure ~ 4 psi). I can blow through the outlet pipe (horizontal on RHS) easily, but the inlet (vertical entry LHS) was VERY HARD! Can see the filter thing, but cant get it out. If it misbehaves again, I will try flushing with injector cleaner and see if that helps.
Want me to fax you some Watson pages? Can you get a gauge set to go on it? You need some adapters - M12x1.5 to M10x1, M10x1 to M8 x1 , 100psi Gauge on a T piece, and a tap on one leg.
jp

Jack in Malta

Hi JP

I have cjecked the flow rate from the fuel pump and its fine, i have checked the return line and thats OK to. I find it very difficult to blow through the WUR from either side but there is a passage through here as there is a good flow of fuelk back to the tank. The pressure builds quickly.

The fax would be an enourmous help. My number is +356 for Mlata, 21446227 so it should be 00356 21446227 from the USA ( I order the book from Amazon but it takes a few weeks to get here)

The source of this is from the top of the fuel distributor whcih goes through the diaphram damper (its new) and the solenoid valve (this appears to be operating)

Dennis Wilson

The screen will either be at the coupling on the inlet side of the WUR or at the inlet from the fuel pump to the fuel distributor. Did you check your pressures with the valve on the WUR side of the gauge? Have you checked for system pressure at the inlet side of the WUR? If the system pressure is too high at the inlet your bypass/relief valve is at fault. Have you taken it out and checked it?

Dennis

Dennis Wilson

JP,

In your post to Jackin you mentioned the control pressure is measured with the gauge on the inlet side of the WUR. To clarify, the inlet line runs from the drivers side of the fuel distributor. The control pressure measurement should be taken on the outlet line of the WUR which runs to the center outlet on top of the fuel distributor. When positioning your tester the valve should be on the WUR side of the gauge. With the valve open you are measuring control pressure. With the valve closed you are measuring system pressure. Which side are you testing from?

Dennis

jpitman1

Dennis,
See P 25-8 of Manual Vol 1A Engine. Shows pipe entering WUR vertically (tube nut) removed, fitted to one leg of Gauge; Other side of gauge has valve, then goes onto WUR fitting the above pipe was removed from. On mine now with valve open I get 42psi (control), valve closed 75psi (system). When it was bad, control was 65psi+, and when I opened the OTHER fitting on WUR( banjo fitting), NOTHING, or only a few drips came out.
Yes, the inlet line is on the driver side, as mine is a RHD unit.
jp

Dennis Wilson

JP,

Sorry about the confusion on the inlet and outlet. Think the manuals refer to the lines as control and pressure relief. I think of a valve as inlet being high pressure (from the pressure relief valve) and low pressure (to the top of the distributor). i.e. High being the inlet and the outlet being low. Seems simpler for me. From the picture in chapter 25, it is the correct line that runs on your drivers side and to the top of the distributor.

Dennis

Jack in Malta

Hi Now I am confused.

I have a Euro 928 1982. The lines are like this

I have a line from the top of the fuel distributor which runs to a diaphram damper, this in turn goes to the solenoid valve which has a disributing piece. One pipe goes into the WUR and connects to the side without the gauze (vertically) and the other outlet from the solenoid (when activated) goes to a union that is on the pressure relief valve. There is another pipe that goes from the (gauzed side) of the WUR back to the pressure relief valve outlet so its effectively joined in a loop

Is this correct?

I have high pressure on the side that comes from the top of the fuel distributor and lower pressure on the side that goes to the pressure relif valve.

HELP!!!!

Thanks

Dennis Wilson

Jacklin,

Sounds like you have the next version which uses a flappy and fuel pressure regulator instead of a WUR.

Dennis

jpitman

Jackin(paul),
On mine (83 Euro S), line comes from centre of distributor head, to diaphragm, to solenoid (hot start valve) to WUR, vertical entry with filter screen under it. Other side of WUR leaves horizontally, goes down LH side of engine (looking in) to lh side if distributor, where it units with another pipe returning to tank. Thats it, no other fuel pipes. If you think about the regulator function, I dont think it matters which fitting is inlet or outlet, it will still regulate the pressure. It does matter which pipe is which though - supply and return functions are very different in pressure. I dont recall seeing such a pipe arrangement in the manuals, but I was only looking for mine (M28/12 engine). What is the code on your engine - on the boss left of the thermostat housing?
jp

Jack in Malta

Hi

I have a 928S, it does have the flappy and the other unit looks like a WUR, it has the vacuum feeds and the bimetal strip internally which receives 13volts when the engine is running.

I thought the fuel supply to the WUR is from the top of the fuel distributor head and the return is to the bottom of the fuel distributor head from the outlet of the WUR (left side when standing in front of the car). My pressure is high from the line on the top of the Fuel distributor to the WUR side and low on the side that returns to the base of the fuel distributor