how much pressure for pusher pump?

[emarsh]

What is the pressure range for a pusher pump near the tank? Can you use a 7 psi Carter type automotive (gas) pump. I wouldnt think it had to deliver much pressure, just some volume to feed the lift? pump.

I use one of these on my early bronco to feed the high pressure fuel injection pump, and it works great.

 

[redneckdr]

pusher

7 PSI is about right. opinions about flow vary. some want a high flow pump (100gph), others say not so important. standard OEM fuel filter flows about 45 gph??? i have an aftermarket diaphragm pump as a pusher. just got gauges on, and i'm not too happy with my pressure at WOT (5 or slightly below). got 16 at idle, and 12 at steady 60 mph. i'm going to take the pusher out of the line this w/e and see what i have.

 

[Mopar-muscle]

7psi pump is fine , if you have to stock lift pump on the engine still get the 70 gph pump .



you will more than likely end up than higher than called for pressure at the injection pump by dodge , whether that is good or bad is still unknown .



it will be your problem to deal with if dodge decides its a bad thing ...

 

[Steve St.Laurent]

John, have you seen data somewhere that states the maximum pressure from Dodge or Cummins? The only spec I have ever seen in print is that they state a minimum of 10 psi of pressure at the inlet in the service manual. I contacted one of the D/C engineers responsible for our trucks as well as a Cummins engineer when I put my pusher pump on and saw the pressures I was getting (19 psi max) and both of them said 20 psi would be no problem (I didn't ask about higher pressures as that's all I was seeing) - with the exception of the possible hard to start problem if fuel pressure was over 7 psi while cranking (which I've covered before). The concern that has been posted here with a high fuel pressure at the pump was the seals in the pump, since I know of two vendors (DTT and TST) that have done tests with up to 60 psi at the inlet with no problems (no benefits either) I'm not worried at all running 19. Some guys (very few) have even been seeing their 16 psi gauges pegged with a new stock replacement pump.

 

[redneckdr]

pumps

steve, at what pressure (low) at the VP44, do you start to worry?with WOT. mine falls to 5, then levels off. is that enough, or should i worry? 16 at idle, and 10-12 at steady 60mph.

thanx in advance

 

[Steve St.Laurent]

As far as what pressure to start worrying about, I can't tell you. What I can tell you is what I've heard and experienced personally. A Bosch rep at the Scheid event last year said you could trickle fuel into the VP44 as long as it was never starved for fuel and it would be ok, in other words anything over 0 psi - however he had no fuel flow or pressure requirements which makes me doubt his claims somewhat. In June at Thunder in Muncie I was down to 4 psi at WOT on my lift pump and my peak boost was down by 4 psi as well (36 psi max boost versus 40 max normally at that point) - my 1/4 mile times were off by about . 5 seconds too. For myself I will get concerned and start looking into things if I see anything less than 10 psi of fuel pressure at the linlet since that's what Dodge calls for in their service manual. That being said, none of the stock lift pumps that I have put on (4 of them) have ever had more than 10 psi of fuel pressure at WOT, until I put on the pusher pump setup. Others would probably disagree with me and say any positive pressure at the inlet to the VP44 is fine, so this is JMHO - I'm not an expert.



-Steve

 

[redneckdr]

pushin'

thanx, steve. last night on the way home, i floored it when possible, and the numbers are not encouraging. i'm getting down to about 3 PSI with a longer WOT run. for "R&D", i've been trying a diaphragm aftermarket pump as a pusher. i think i've found something NOT TO DO. i'm going to bypass the pusher today, and see what i'm running. i think i see a Mallory or another Carter in my future.

 

[mbrolin]

I personally think that any reading less than 4psi at WOT is cause for replacement.

 

[15w40]

Here are the numbers for fuel pressure published in Cummins, "Troubleshooting and Repair Manual ISB and QSB5. 9 Engines", BULLETIN No. 3666193-01:



Maximum Fuel Inlet Restriction to Lift Pump ………………………… 6 inches Hg

Maximum Fuel Pressure at Fuel Filter Outlet (engine cranking) ……… 4 to 8 psi

Minimum Fuel Pressure at Fuel Filter Inlet (engine running) ………… 8 to 17 psi

Maximum Pressure Drop Across Fuel Filter …………………………. . 5 psi



If I combine the worst case specifications of 8 psi at the inlet to the fuel filter and a 5 psi drop across the "dirty" filter, that allows 3 psi minimum at the fuel filter outlet or inlet to the injection pump. I have found no specifications on the maximum fuel pressure allowed other than the 8 psi with the engine cranking.





Hope this helps.

 

[15w40]

One more thought about pressure

A lot of over-valved Diesel Ram owners have added a fuel pressure guage to their trucks to keep an eye on the lift pump. I took a different tact and changed from a guage to a beeper. Here is my reasoning. I don't care if the fuel pressure is 15 psi or 5 psi. As long as it is a positive pressure, my injection pump is happy. In my experience with a failing lift pump, the pressure becomes erratic as it nears the end of its life. It may be 10 psi one minute then fall to 1 or 2 psi the next. This is based on my observations and from reading all the different posts about lift pumps. If the fuel filter clogs from a bad load of fuel, this will also drop the pressure to the injection pump to a dangerous level. Finally, I have a hard enough time keeping an eye on my EGT when drag racing the phord in the next lane. The added fuel pressure guage just does not get noticed.



Here is an ASCII art diagram of my solution.

  Piezo Beeper

 Ignition Switched +12 V |-----|

>---------------------------------|+   -|---+

  From cigarette lighter |_____|   |

  |

Ground  /o-------+

>--------------------------------o/ 

   o

  Pressure Switch (using normally closed contacts)

What is nice about this system is when the ignition is switched on and the lift pump starts in its low-pressure mode, the beeper is silent. As I wait for the "Wait to Start" lamp to go off, the lift pump will have stopped and the beeper sounds as a self-test. If I hear the beeper when accelerating, I will let off and take it easy, then try changing the fuel filter. If that doesn't work, it is time for another lift pump.

The pressure switch is made by Nason and is pre-set at 4 psi with a 1/8-inch male pipe thread. It has a normally closed and open set of contacts. I found this switch at MSC Industrial Supply Co. for about $24, pn/ 56499007. Check the web for an online catalog. The piezo beeper came from Radio Shack. I got a loud beeper and dropped it into the ashtray. I will hear it even when the Cummins is in full song.

 

[redneckdr]

pressures

the pusher is out of the line. 14 PSI at idle, 10-12 PSI at steady speed, and no lower than 6 PSI @WFO (WOT). guess the old pusher is there for emergencies. this is a DON'T DO to help pressures. i think it helps at low speeds and idle, but must decrease flow/pressure with WOT.

 

[emarsh]

a diaphram pump is a positive displacement pump, the total output of all downstream pumps will be LIMITED by the volume of the pusher if it in fact a diaphram type. Diaphram pumps are generally low volume by design and should not be used in this application, although they suck great as opposed to a gearotor type, which is designed to push.

 

[Mopar-muscle]

steve , correct , i seem to have beaten the anti pusher pump subject to death . my cause is fueled in part by the fact that people are being led to believe they need something when they possibly don't ... and then a company name is attached to the item all in the name of making a buck. i could never be a business man because i wouldn't be able to sleep at nite knowing i was selling people stuff they didn't need just so i could make money ... but thats me ... ok ... off the soapbox .



as far as drag racing problem you state, what was the pump you were using when that happened and where was it located ? i'm going to guess stock in stock location .



i have had the carter 4601hp,15psi ,in the stock location powered by the stock power ,since about march of 2001 , guessing 30k miles , never goes below 5psi and i make 50psi of boost , am i doing something wrong other than being to lazy to move it back to where it should be ?



for warranty situations , which seems to be the big concern with most , there is no winning situation , you either move the pump back to where it should be , or add a pusher , either way you slice if you go in for a failed stock lift pump dodge and its network of do nothing dealerships will blame you because its not as delivered from the factory. fix it yourself and warranty it yourself ... plain and simple.



i looked at this problem from my own perspective and using my 23yrs experience (i've been messing with cars since i was 15) and did what testing i could as cheaply as i could , then posted it for all to see . some have chosen to take that data and expand their product line with their name slapped on it . good for them , free R+D . . good they have to warranty it , not their R+D team ...



one thing i do know , the stock limp pump is not the pump to have in the system if your truck is not BONE stock . i am thinking now that part of my large increase in at the track could be in part to having changed from the stock lift pump to the HP carter , but i also changed from a 91% tc to a 93% ... but then i throw that all out the window when i witnessed a 2000 2500 4x4 reg cab ram do a 13. 8 with BD4's , EZ and a blue box at 50% , stock TC and COMPLETELY STOCK AS DELIEVERD FROM DODGE fuel system .



he's waiting to see what i break before he adds an HX40 and a DTT TC ... his truck should run a 13. 0 ??? maybe 12's ???



Happy Holidays ...

 

[redneckdr]

pushers

alright, the pusher is back in the line. bypassed the inline filter i had in. no change from with it inline. i'm gonna leave it in, and run it--my reasoning--my pressures are higher with the pusher inline, EXCEPT for those infrequent WOT runs. gotta be less than 1% of my driving. the pusher will push through the OEM any time it is on, and the OEM isn't pumping, with 7PSI of pressure. i have 16-17 PSI at idle with the pusher inline with the OEM, and 11-12 at cruise. those pressures are better than with the OEM alone, by 2-5 PSI. the only time my pressure drops below 5 with the pusher inline, is with a LONG WOT run. it then levels off at about 3-4 PSI. we'll see what happens. I AM MY OWN WARRANTY STATION.

 

[Jetpilot]

Mopar-Muscle



I will be upgrading my trucks fuel system soon..... I was going to use a Holley 4140M pump (out in the garage now), but the Carter pump you are running sounds like it is doing the trick. Did this pump bolt right up in the stock location? Also how did you wire it in? From what I can see it looks like on the 2001's that the OEM pump has a wiring harness that is used.



Just a few questions, as always I am trying to get the most bang for my buck. It also looks like the carter pump is a much easier install.



Thanks,



Doug S.