Mercedes spring for 3b-t turbo tuning (1 Viewer)
- Thread starter bj70bc
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- Thread starter
- #2
I opened up the injection pump to install the merc spring on the diaphragm and saw my diaphragm is torn in two places
damn it
now i have to do that too i guess.....
at least I found it, i wonder if this has been contributing to the lack of power i was sensing, just always seemed like it should have more grunt.
with a new diaphragm and better fuel delivery via the merc spring this thing should rip....better
i think im going to rotate the reference line 45* at the throttle plate, that goes to the diaphragm cavity as well at the same time
i've read that this improves pickup on throttle tip-in up to mid-range
moar powa
I highly recommend anyone that doesnt know the condition of their diaphragm to check it. It sucks to do, but isnt impossible by any means. It could be fooked
damn it
now i have to do that too i guess.....
at least I found it, i wonder if this has been contributing to the lack of power i was sensing, just always seemed like it should have more grunt.
with a new diaphragm and better fuel delivery via the merc spring this thing should rip....better
i think im going to rotate the reference line 45* at the throttle plate, that goes to the diaphragm cavity as well at the same time
i've read that this improves pickup on throttle tip-in up to mid-range
moar powa
I highly recommend anyone that doesnt know the condition of their diaphragm to check it. It sucks to do, but isnt impossible by any means. It could be fooked
I first thought the diaphragm was a damper thing to avoid the truck rocking when going off road but I think now this entire set up as something to do with black smoke control.
Behave like a « delay » between injection pump fuel rack and the floor pedal. Fuel rack is controlled by how much air is going into the engine. (Kind of) so it is not really possible to create unburdened fuel smoke.
I guess that if someone wants a direct linkage, the floor pedal could be physically linked to the fuel rack. The 13BT/12HT didn’t have that system.
If the diaphragm is completely tear up, it won’t control at all the fuel rack and engine will max rev (4000rpm) all time, don’t think it is related to your engine power you think of. Did you increase your max fuel delivery (screw)? The lobe on the fuel pump camshaft must wear with time hence not allowing full plunger stroke (just a thought). Allowing more fuel by unscrewing the max fuel screw may help regaining original engines power…
Did you check the fuel pump injection timing (FSM procedure), it could be off.
Behave like a « delay » between injection pump fuel rack and the floor pedal. Fuel rack is controlled by how much air is going into the engine. (Kind of) so it is not really possible to create unburdened fuel smoke.
I guess that if someone wants a direct linkage, the floor pedal could be physically linked to the fuel rack. The 13BT/12HT didn’t have that system.
If the diaphragm is completely tear up, it won’t control at all the fuel rack and engine will max rev (4000rpm) all time, don’t think it is related to your engine power you think of. Did you increase your max fuel delivery (screw)? The lobe on the fuel pump camshaft must wear with time hence not allowing full plunger stroke (just a thought). Allowing more fuel by unscrewing the max fuel screw may help regaining original engines power…
Did you check the fuel pump injection timing (FSM procedure), it could be off.
Last edited:
- Thread starter
- #4
the diaphragm controls throttle, by the vacuum and reference line, moving the fuel rack.
if the diaphragm is torn it can rev high on idle, blow black smoke (over fuel), have poor fuel economy, low power.
im just attempting, with the different diaphragm spring to allow a more responsive fuel delivery upon applying throttle.
having the diaphragm being torn certainly wont help things.
i get what your saying though, the symptoms are usually high idle, but sometimes it can appear as poor throttle response.
i have adjusted timing and main fuel accordingly for the turbo, im just trying to optimize the system for better driveability.
if the diaphragm is torn it can rev high on idle, blow black smoke (over fuel), have poor fuel economy, low power.
im just attempting, with the different diaphragm spring to allow a more responsive fuel delivery upon applying throttle.
having the diaphragm being torn certainly wont help things.
i get what your saying though, the symptoms are usually high idle, but sometimes it can appear as poor throttle response.
i have adjusted timing and main fuel accordingly for the turbo, im just trying to optimize the system for better driveability.
