Stuck Control Plunger
Discussion
My 280i has been parked much too long. After replacing the fuel pump the engine idled but would not rev up. We diagnosed this as the control plunger being stuck in the fuel distributor.
Removing the air filter allowed me to push it up; now it is stuck. I sprayed carb cleaner but that hasn't released it yet. I was hoping that the fuel pressure would push it back down, but the fuel just goes straight to the injectors.
Should I get six screws to close the holes for the six injector lines (and maybe a seventh for the "choke")? I hope I do not have to dismantle the fuel distributor.
Any ideas would help.
Wilf.
Removing the air filter allowed me to push it up; now it is stuck. I sprayed carb cleaner but that hasn't released it yet. I was hoping that the fuel pressure would push it back down, but the fuel just goes straight to the injectors.
Should I get six screws to close the holes for the six injector lines (and maybe a seventh for the "choke")? I hope I do not have to dismantle the fuel distributor.
Any ideas would help.
Wilf.
Hi Mark,
Yes the clip, and everything else looks fine. The round plate only moved a little, just enough for idle. I took off the air filter and pushed the plunger up to where it would be for full throttle. It was obviously all gummed up, and I it doesn't want to come down.
I do not want to dismantle the fuel distributor. My only solution is to get pressure above the plunger by plugging the holes which feed the injectors, and getting the fuel pump to put enough pressure to push it back down. I was hoping somebody has had this problem and found a better solution.
I will need to buy fine thread bolts, and cannot do this until Monday. Meanwhile I sprayed plenty of carb cleaner.
Wilf.
Yes the clip, and everything else looks fine. The round plate only moved a little, just enough for idle. I took off the air filter and pushed the plunger up to where it would be for full throttle. It was obviously all gummed up, and I it doesn't want to come down.
I do not want to dismantle the fuel distributor. My only solution is to get pressure above the plunger by plugging the holes which feed the injectors, and getting the fuel pump to put enough pressure to push it back down. I was hoping somebody has had this problem and found a better solution.
I will need to buy fine thread bolts, and cannot do this until Monday. Meanwhile I sprayed plenty of carb cleaner.
Wilf.
Yeah it could be gummed up..You could try that as when the plate is up the channels are open so its not affected by pressure..I can ask my Ford guy on Tuesday if you are still stuck to see if he has ever come across it..I was thinking a blast of high pressure air but that might damage the fine mesh inside the unit....Ziga
Thanks, Mark.
I am still thinking of non-destructive solutions!
There are three screws on he top of the fuel distributor, which should let me split it. But I cannot loosen them and am scared of damaging them. Have you ever worked on them?
On this side of the pond, many cars (Volvo, VW, Rolls, Porsche and maybe BMW) used a similar Bosch system. Maybe tomorrow I should go to see someone who specializes in them.
Wilf.
I am still thinking of non-destructive solutions!
There are three screws on he top of the fuel distributor, which should let me split it. But I cannot loosen them and am scared of damaging them. Have you ever worked on them?
On this side of the pond, many cars (Volvo, VW, Rolls, Porsche and maybe BMW) used a similar Bosch system. Maybe tomorrow I should go to see someone who specializes in them.
Wilf.
Hi mate..I did once try to undo them with on a spare that i had but no joy...I know there is a particular fuel friendly sealant..(Aircraft grade) between the unit so it wouldn't be credible to split it..If you can get hold of a second hand one to refurbish then that might be better...Its always good to have a spare to either rebuild or exchange...Hope you sort it...Ziga
Yes, Mark and Ian, I was told the same thing about never dismantling it. My three screws have flat heads; I put quite a lot of torque on them but they didn't want to budge. At least I didn't damage them.
It is hard to find the same distributor here. There were many 4 cylinder versions; I will check online.
Tomorrow I will buy enough bolts with the same threads as the banjo bolts and try to block all the outlets (to six injectors and the "choke") and see what the fuel pump can do. Near where I buy the bolts I have a friend who knows everything there is to be known about older BMWs, and see wht he suggests.
Am I the only person that has had this problem? With all the barn finds we read about, I would have thought this would not be uncommon.
Wilf.
It is hard to find the same distributor here. There were many 4 cylinder versions; I will check online.
Tomorrow I will buy enough bolts with the same threads as the banjo bolts and try to block all the outlets (to six injectors and the "choke") and see what the fuel pump can do. Near where I buy the bolts I have a friend who knows everything there is to be known about older BMWs, and see wht he suggests.
Am I the only person that has had this problem? With all the barn finds we read about, I would have thought this would not be uncommon.
Wilf.
A bit of crud may of worked itself loose and jammed it...I certainly didn't experience this with Delilah even though the fuel system was contaminated and the metering unit fouled with rust after sitting around for 11 years and then the guy who sold it me deciding.."Oh its a lovely day...Lets see if this old TVR will start"..He probably thought to himself.."Bloody hell i thought they had a reputation of being un-reliable"..Then whilst posing like a Tw@t in his newly acquired 2 seater retro sportster 
..There was a moment of horror when it starts to cough and splutter on the highway miles from home...
....."Maybe i shouldn't have just started it and taken it for a spin after its been sat for 11 years'..Errrr..."Hey Dumbarse" would of been my chosen word...
The rest is history..In fact where is she....
Anyway if you can't find another then find someone who knows what they are doing as rebuilding the unit...There is a factory setting for the unit as far as fuelling...If you need any technical data like this then i know of someone.
Hopefully you will be able to un-stick it but not knowing why its stuck would be my main question..Also if i remember rightly the three screws on top secure the unit to the plate housing..I think they are sealant sealed and as said the sealant is VERY important...They guy who rebuilt mine has worked on them for 30 years and the one he built first leaked due to the change in the ethanol and additives in modern fuels...Don't forget i was running a supercharger so the ron was better higher than lower as i had a special type of spark plug for that application.
He replaced the unit with one that had a different aircraft grade sealant holding the two plates together inside...This sealant was Re-approved recently in its application...Well in 2010 or thereabouts again due to fuel's so called "Urbanisation" or more appropriately "The dilution of oil ppm over organics" upgrade...My how expensive this so called "Green living" costs...Actually i think thats it...We are f
king green.....
..Maybe "Waste" is a good thing...They make it bad so we give it to them free and then they sell it back to us for extortionate amounts of money..And call it TAX..(Take All..Xactly)..Sorry bit of a Sunday debate going on with my split personality...
..There was a moment of horror when it starts to cough and splutter on the highway miles from home........"Maybe i shouldn't have just started it and taken it for a spin after its been sat for 11 years'..Errrr..."Hey Dumbarse" would of been my chosen word...The rest is history..In fact where is she....
Anyway if you can't find another then find someone who knows what they are doing as rebuilding the unit...There is a factory setting for the unit as far as fuelling...If you need any technical data like this then i know of someone.
Hopefully you will be able to un-stick it but not knowing why its stuck would be my main question..Also if i remember rightly the three screws on top secure the unit to the plate housing..I think they are sealant sealed and as said the sealant is VERY important...They guy who rebuilt mine has worked on them for 30 years and the one he built first leaked due to the change in the ethanol and additives in modern fuels...Don't forget i was running a supercharger so the ron was better higher than lower as i had a special type of spark plug for that application.
He replaced the unit with one that had a different aircraft grade sealant holding the two plates together inside...This sealant was Re-approved recently in its application...Well in 2010 or thereabouts again due to fuel's so called "Urbanisation" or more appropriately "The dilution of oil ppm over organics" upgrade...My how expensive this so called "Green living" costs...Actually i think thats it...We are f
king green.......Maybe "Waste" is a good thing...They make it bad so we give it to them free and then they sell it back to us for extortionate amounts of money..And call it TAX..(Take All..Xactly)..Sorry bit of a Sunday debate going on with my split personality...Mark,
I looked at some YouTube videos of people working on fuel distributors; the Porsche 928 and Mercedes look same design, but 8 cylinders. One used shellac to put the two halves together; the other said use nothing as it is machined!
Yes I will go to my BMW friend tomorrow and see what he says.
Wilf.
I looked at some YouTube videos of people working on fuel distributors; the Porsche 928 and Mercedes look same design, but 8 cylinders. One used shellac to put the two halves together; the other said use nothing as it is machined!
Yes I will go to my BMW friend tomorrow and see what he says.
Wilf.
Hi Wilf...Been thinking about this and had a little chat with my Ford friend just to clarify what i thought..Now the three flathead/Slotted screws hold the unit to the plate, There is a ring like gasket..You will need to remove the top fuel hose to get to the third screw...Don't touch the 3 x torque head/Star driver screws.
Its possible that you have pushed the plate far enough up so that the plunger is stuck on one of the recesses inside the plunger housing..By removing the metering head from the plate housing you should be able to free it and the plate should drop down...If it doesn't then it must be caught somewhere...Hope this helps...Ziga
Its possible that you have pushed the plate far enough up so that the plunger is stuck on one of the recesses inside the plunger housing..By removing the metering head from the plate housing you should be able to free it and the plate should drop down...If it doesn't then it must be caught somewhere...Hope this helps...Ziga
Hi, I've been following this post with interest as I will soon be facing similar problem of a fuel system which has laid dormant for a number of years. Advice so far is to flush tanks etc and to soak the metering/distributor head in the fluid used to clean paint spray guns? Any thoughts please? Cheers John C.
Mark & John,
I went to my BMW buddy yesterday; he had just got back from a big weekend at Sebring celebrating the 75th Anniversary of the first 24 hour races there. He has driven in many of them.
His advice was to undo the three screws holding the top down. I told him this is near impossible, but he said they do it with an impact screwdriver. It has been raining too much to try. I asked about plugging the outlets from the fuel distributor, and using either the pressure from the fuel pump, or using an air compressor regulated down to a low pressure, and then increasing it until the plunger moved. My guess is that when I pushed the plunger up, I only used 4 or 5 pounds of force; 70 psi on a 14mm plunger should be more than enough to move it. But it didn't. Fuel poured out past the eight or so screws I put in the outlet holes; I didn't want to put anything to seal them that I couldn't remove.
I think Mark may be right that I pushed the plunger too far.
When the rain is less, I will try again.
Wilf.
I went to my BMW buddy yesterday; he had just got back from a big weekend at Sebring celebrating the 75th Anniversary of the first 24 hour races there. He has driven in many of them.
His advice was to undo the three screws holding the top down. I told him this is near impossible, but he said they do it with an impact screwdriver. It has been raining too much to try. I asked about plugging the outlets from the fuel distributor, and using either the pressure from the fuel pump, or using an air compressor regulated down to a low pressure, and then increasing it until the plunger moved. My guess is that when I pushed the plunger up, I only used 4 or 5 pounds of force; 70 psi on a 14mm plunger should be more than enough to move it. But it didn't. Fuel poured out past the eight or so screws I put in the outlet holes; I didn't want to put anything to seal them that I couldn't remove.
I think Mark may be right that I pushed the plunger too far.
When the rain is less, I will try again.
Wilf.
The impact screwdriver worked a charm. I expected three short bolts, but in fact they are about 2" (50mm) long, and hold the top two pieces to the third. And of course the top two are stuck together. Then the rain started.
But not enough rain to stop me going out to celebrate Cinco de Mayo.
Wilf.
But not enough rain to stop me going out to celebrate Cinco de Mayo.
Wilf.
pasogrande said:
The impact screwdriver worked a charm. I expected three short bolts, but in fact they are about 2" (50mm) long, and hold the top two pieces to the third. And of course the top two are stuck together. Then the rain started.
But not enough rain to stop me going out to celebrate Cinco de Mayo.
Wilf.
So did the plunger pop back and the plate lower down..Or are you just celebrating the rain ..But not enough rain to stop me going out to celebrate Cinco de Mayo.
Wilf.
Not to hijack, but on the related topic, mine too has been sitting but I'm getting running again. It starts right up and runs but will not idle. I'm going to dump the old gas and replace the filters. I have been advised to run some Seafoam though it to clean out the fuel system. Then if it doesn't work, to start fault checking.
Anyone know this is a BAD idea? Grady
Anyone know this is a BAD idea? Grady
Edited by Grady on Wednesday 20th May 00:47
Hi mate...Im not sure about the seafoam...I would be tempted to first empty the fuel tanks...Make sure they are not flaky by looking in there with a good inspection camera...Change fuel filter and if the tanks are good then put some fresh fuel in with some injector cleaner...Not too strong but slightly more than you would normally...Kinda..Check all air and water hoses before you attempt to start it..Personally i would check or fit new spark plugs, Rotor arm and dizzy cap And have a spare coil handy..Then if you have one by-pass the fuel cut off so that when you turn the key to position 1 the fuel pump starts instead of on cranking...On UK cars there is a green two pin connector plug on the unit itself and by un-plugging it the fuel pump runs..I would do that to 1. Check that there is no fuel leaking from potential ruptured plastic fuel lines from the metering unit and 2. Prime the system for a second or two ..Then start...Hold revs for a minute or so and then see if it idles..
I've never used seafoam but from the testing I've seen I wouldn't use it. RedLine has a fuel injector cleaner that has had very positive reviews. I used some in my 280i and I believe it helped make the engine run better. Auto Zone / Advance Auto / O'Reilly's stock it. I'm a fan of RedLine products and use their MTL oil in my transmission and 75W90 gear-oil in the rear-end.
My car idled OK but the idle adjustment screw had no effect. Previous owner had been adjusting the idle via the butterfly. I removed the air intake tube and could see gum around the edge of the butterfly. With some carb cleaner I cleaned away the gum. I also removed the idle screw and that too was all gummed up around the tip. Gave that a really good clean as well and once reassembled the car now has a smoother idle and the adjustment screw now works.
The only issue I have still to resolve, is a high idle on a hot start. It will idle at 1300 rpm from start up for a few minutes then drops down to 900 rpm.
My car idled OK but the idle adjustment screw had no effect. Previous owner had been adjusting the idle via the butterfly. I removed the air intake tube and could see gum around the edge of the butterfly. With some carb cleaner I cleaned away the gum. I also removed the idle screw and that too was all gummed up around the tip. Gave that a really good clean as well and once reassembled the car now has a smoother idle and the adjustment screw now works.
The only issue I have still to resolve, is a high idle on a hot start. It will idle at 1300 rpm from start up for a few minutes then drops down to 900 rpm.
Edited by GBinUSA on Saturday 16th May 01:43
Edited by GBinUSA on Saturday 16th May 01:44
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