+- STD (https://www.superturbodiesel.com/std)
+-- Forum: Tuning (https://www.superturbodiesel.com/std/forumdisplay.php?fid=6)
+--- Forum: Engine (https://www.superturbodiesel.com/std/forumdisplay.php?fid=7)
+--- Thread: fuel pump pressure (/showthread.php?tid=2765)
fuel pump pressure - Hercules - 06-30-2011
Decided to ck. lift pump pressure,was 10lbs,but gauge was oscillating between 0-10lbs almost too fast to read. pressure gauge is good and of good quality. decided to install older check valve in pump and stretch spring to 22mm and book says 26-27mm, pressure now 30lbs still oscillating. 0-30. tested check valves in lift pump both sides work well section side holds vacuum pressure side holds pressure made this test at outlet and inlet of pump. volume on pump is also good, springs on check valves stretched a small amount. checked dead end pressure of pump 65lbs still oscillating between 0-65. any ideas why it is oscillating so greatly?? car runs well and always did. thanks.
RE: fuel pump pressure - winmutt - 06-30-2011
Sucking in air?
RE: fuel pump pressure - DeliveryValve - 06-30-2011
Don't sweat it. It's normal, that's way it pumps with the oscillation. Good you got the pressure up though.
.
RE: fuel pump pressure - Hercules - 06-30-2011
Thanks,Thought it might be normal,others experiences very helpful,book is of no help on this. by the way ,have noticed some over all performance increase. Older ck. valve very cheap at local yards.
RE: fuel pump pressure - dieselboy - 06-30-2011
What's the spec?
RE: fuel pump pressure - Hercules - 06-30-2011
20lbs,measured between filter and inj.pump.
RE: fuel pump pressure - Captain America - 07-01-2011
You stretched uour spring to 22 when spec was 26-27?
RE: fuel pump pressure - Hercules - 07-01-2011
Yes, 22mm gave 30lbs pressure,this was stretching spring about 4mm,easy to stretch hard to undo without cutting spring.
Just got the impression that stretching the spring that much would be too much,glad i listened . Checked pressure two places
four diff.times after venting (bleeding) system,pressure same.
RE: fuel pump pressure - Captain America - 07-01-2011
Where IS the spring?
RE: fuel pump pressure - DeliveryValve - 07-01-2011
It's located between the IP and engine block on the banjo of the hard plastic return line.
RE: fuel pump pressure - DeliveryValve - 07-02-2011
Checking Fuel Pump and Bypass Valve procedure.
.
RE: fuel pump pressure - richclan - 07-02-2011
if i stretch spring to 26-27mm could it create too much fuel pressure and if it did what would go wrong/break.
i dont have a pressure gauge so i dont want to create a problem
tks
RE: fuel pump pressure - DeliveryValve - 07-02-2011
(07-02-2011, 01:50 PM)richclan if i stretch spring to 26-27mm could it create too much fuel pressure and if it did what would go wrong/break.
i dont have a pressure gauge so i dont want to create a problem
tks
Yes it can. Most springs I pulled are around 20mm and a little stretch can bring the pressure up. I don't know how Mercedes came with that spec.
You can stretch it 1 mm at a time and see what each results are, just don't go over board. In the end you really ought to do it with a gauge.. Namely a glycerin filled gauge to counter act the oscillation which can be so severe you can't read the gauge.
.
RE: fuel pump pressure - mr_manny - 07-03-2011
(07-01-2011, 03:48 PM)DeliveryValve It's located between the IP and engine block on the banjo of the hard plastic return line.
Just checked my IP, and my bolt looks like a regular banjo bolt....what's with that?
RE: fuel pump pressure - mr_manny - 07-03-2011
I can see a spring inside, but don't see how it would be possible to remove...let alone re-install.
![[Image: IMG_20110703_061252.jpg]](http://i41.photobucket.com/albums/e287/mr_manny/IMG_20110703_061252.jpg)
guess I have a newer check valve
RE: fuel pump pressure - Alastair E - 07-03-2011
Thats the later type--NON Adjustable....
Only the Older type are adjustable--They have a hex-head on the back end of the main head to unscrew...
RE: fuel pump pressure - mr_manny - 07-03-2011
(07-03-2011, 01:36 PM)Alastair E Thats the later type--NON Adjustable....
Only the Older type are adjustable--They have a hex-head on the back end of the main head to unscrew...
not fair
RE: fuel pump pressure - mr_manny - 07-04-2011
What If something was added to create additional back pressure?
Wondering if the higher back-pressure would achieve the same results, as extending the spring...
Any fellow later-banjo owners try this?
RE: fuel pump pressure - dieselboy - 07-04-2011
You want a adjustable one? I think I have a few.
RE: fuel pump pressure - hansebanger77 - 07-04-2011
(07-04-2011, 01:15 AM)dieselboy You want a adjustable one? I think I have a few.
I need this too
RE: fuel pump pressure - mr_manny - 07-04-2011
(07-04-2011, 01:15 AM)dieselboy You want a adjustable one? I think I have a few.
would be sweet..let me know how much
manny
RE: fuel pump pressure - mr_manny - 07-05-2011
Was wondering, has anyone plumped an analog pressure gauge under the hood?
Being able to verify fuel pressure with only a glance, seems like a good thing to me
RE: fuel pump pressure - DeliveryValve - 07-05-2011
(07-05-2011, 02:40 PM)mr_manny Was wondering, has anyone plumped an analog pressure gauge under the hood?
Being able to verify fuel pressure with only a glance, seems like a good thing to me
You mean keeping it under the hood? That would be fine.
But putting it in the cabin, some manufactures think the pressure is too great to put it in the cabin and may cause injury if something goes wrong.
Here are a couple gauges that should work.
http://www.summitracing.com/parts/FRA-900004/?rtype=10
http://www.jegs.com/i/Auto+Meter/105/5412/10002/-1
.
RE: fuel pump pressure - mr_manny - 07-05-2011
(07-01-2011, 03:29 AM)Hercules Yes, 22mm gave 30lbs pressure,this was stretching spring about 4mm,easy to stretch hard to undo without cutting spring.
Just got the impression that stretching the spring that much would be too much,glad i listened . Checked pressure two places
four diff.times after venting (bleeding) system,pressure same.
I did a quick google conversion, and 30lbs pressure seems much higher then stated specifications.
![[Image: fuel.jpg]](http://i41.photobucket.com/albums/e287/mr_manny/fuel.jpg)
0.6 bar = 8.7 psi
0.8 bar = 11.6 psi
2.0 bar = 30.0 psi
I take it the higher pressure helps w/0-60 times?
RE: fuel pump pressure - tomnik - 07-05-2011
Hi,
the lift pump is the limiting factor to go higher than approx. 1.5-2 bar.
Easy to check: run the engine at idle and close the return line from the IP back into the filter with a vice grip and check the pressure between filter and pump (supply side).
When the pressure increases the over flow valve at the IP return side could be better (and you will notice that the engine idles more quiet).
If the pressure stays the same then the valve is o.k. and the lift pump is already at its max.
I am working on 2.5 - 2 bar under all conditions.
The easiest way is to change the spring in the lift pump.
Tom
RE: fuel pump pressure - mr_manny - 07-05-2011
Good info...will try this test once I have a gauge installed.
thanks Tom.
RE: fuel pump pressure - Captain America - 07-06-2011
Delivery Valve is my hero
RE: fuel pump pressure - Hercules - 07-06-2011
What fuel pressure would be too much ?? Mbz said stretch spring 26-27mm I stopped at 22mm. Well not the first time had to redo a repair following mbz instructions! Will leave at present setting,A stretched spring will ,decrease in tension 20% +/- very soon,undampened gauge bounces several lbs.higher,will end up having lower pressure. The higher pressure did improve performance over all speeds ,Just much more fun to drive. I would how ever suggest to stop at 20 lbs of fuel pressure so as not to over stress parts. (Good Day), is finding improved performance, with little money and time!!
RE: fuel pump pressure - Captain America - 07-06-2011
How about adding shims under the spring to increase tension without stretching? Keep in mind I have not looked at one in front of me yet
RE: fuel pump pressure - mr_manny - 07-07-2011
Stainless fuel pressure gauge arrived today.
![[Image: IMG_20110707_201939.jpg]](http://i41.photobucket.com/albums/e287/mr_manny/IMG_20110707_201939.jpg)
Jesse is taking care of me w/an early design Adjustable Banjo
looking forward to pluming this up, need to get more fittings...