Lift Pump Solution?

[CannonBall]

I have decided to install this pump today. No time like the present. I will do kind of a temporary mount just to see how it is going to act.



Csutton, I do not know what power level I am at. I am running a VA, boost fooler with DDstage1's.



Don't worry Larry, the shop will be clean and the cooler will be packed.

 

[CannonBall]

Guys, here is the latest. The install went great. no problems. I will try to post some pictures either later today or tomorrow.



Here is the problem, way to much fuel pressure. This pump is supposed to be rated at 15PSI/68GPH. I have a 16PSI S/W fuel pressure gauge and I am pegged past the 16 mark. I went for a test drive and thought maybe I could get the pressure to drop or even fluctuate under a load. Nothing doing. In 3rd gear, high range 4 wheel drive I nail it, tires a spinning and front end a hopping the fuel pressure stayed buried.



It could be the thicker fuel but this is my plan. First, grab a bite to eat. I have been on this job since 5 am. Secondly, I am planning on drilling out the fitting on the outlet side of this pump. For some strange reason the inlet side is about 5/16's and the outlet side is only about a 1/4 inch. In theory I should be able to increase volume and decrease fuel pressure by doing this I hope.



Anyway, I need a quick question answered. What is the absolute maximum pressure for this system? Regards. Gordon.

 

[Steve St.Laurent]

When I talked with Cummins and D/C engineers they told me 20 psi was no problem, but didn't have a peak spec for it. Here's what you can do to get a better idea of your pressures, put a 30 ohm resistor on the line to the pressure sender (or 3 - 10 ohm in series, etc). That will reduce your shown pressures by 4 psi at the top end of the scale. So 16 psi on the gauge would actually be 20 psi. That's what I did on mine because I hit 20 psi max with my pusher pump setup and I verified it with a mechanical gauge. I wouldn't mess with the size of the outlet on the pump. That won't affect your pressure downstream which is where you are measuring it. Once the line size opens back up (in the fuel line) the pressure goes back down, opening up the outlet of the fuel pump wouldn't affect the pressures at the fuel filter at all and you may get some debris in the pump by doing it.



-Steve

 

[csutton7]

you're not going to get a definitive answer---the guys with two pumps are seeing 22psi--so I wouldn't go beyond that---maybe better to be somewhere between 16-18psi---good luck---chris

 

[tmacc]

A couple of questions.

ynot and C-ball,

Do I understand that you guys are running your stock pumps along w/ the pusher pumps? W/ the pressure your getting, couldn't we just eliminate the stocker?



C-ball, Where did you get the 512-105 and how much was it?

Thanks for the info guys.

Tom

 

[CannonBall]

Steve, I took your advice and cranked a 1K pot down to 30 ohm's and low and behold my fuel pressure gauge read 15PSI. My fuel pressure should be 19PSI. Correct? This should be OK.



TMAC, I got the pump off of Jeg's. I will post picture's etc. Also, I eliminated the factory pump and am just using an inline pump mounted on the frame back near the tank.

 

[Steve St.Laurent]

Correct. Once my fuel is warmed up I'll see 16 psi on the gauge which is 20 psi actual with my dual pump setup, lowest I've ever seen on it is 12 psi on the gauge or 16 psi actual, been running that way for close to 45,000 miles now with no problems. So what are you seeing at WOT throttle now?



-Steve

 

[CannonBall]

Steve, I take it you left the 30 ohm resistor in place? Also, I just came from a test drive. No matter how I drove the fuel pressure gauge did not budge. I tryed wide open starts from a deadstop in four wheel drive (there is sow on some roads) as well as punching it at 60 mile per hour. The gauge does not move. Is this good or bad?



Also, I noticed depending on how I start the engine it will sometimes crank longer. If I just crank it up without waiting the motor starts fine. If I turn the key on and wait for the gauge to peg, go into crank mode, the engine will not fire until the fuel pressure drops to about 13PSI. Normal?



One last thing. I have a small fuel leak now where the water drain goes into the side of the filter housing. I think because of the higher fuel pressure now I have sprung a leak. What seals this area? O-ring? Anyway, let me know if you keep your 30 ohm resistor in place because I will do the same. Regards. Gordon.

 

[CannonBall]

Steve, here is the latest. I just went down to the local Flying J and filled up. Went on a pretty good test drive. I took it up to 110MPH twice. On one occassion I was going 110 uphill. The fuel pressure did not budge. It appears the fuel pressure is 19PSI whether it be at idle or 110MPH uphill.



Holley recomends using 3/8 fuel line with this pump. Do you think this would help maybe lower the pressure and increase volume by running 3/8 from the pump forward?

 

[CannonBall]

Here is a picture

Here is what it looks like mounted on the frame. #ad

 

[CannonBall]

Guy's, how do you post a picture?

 

[CannonBall]

#ad

 

[yogibear]

its still not working gordon. Wish I could help.

Larry

 

[FL70CAT]

30GPH @15psi is plenty for up to 330hp, or a stock truck.

80gph @15psi would be more than enough for bombed applications.

 

[LarryG]

Has anybody considered developing a little head by pressuring the tank? I wonder how much head the plastic tank can stand? For guys with air horns, it would be easier - a little regulator to cut the pressure from an air compressor - both reliable components. I guess you'd need a different cap. Some instrument air regulators have internal relief on them to take care of thermal expansion.

 

[CannonBall]

FL70, supposedly the Carter these trucks come equipped with is rated at 100 GPH at 15PSI. I really do not see how. The pump I am using right now is rated at 68GPH at 15 PSI and it is way to much.



I am starting to think that is just to much volume. I stayed pegged on 19PSI fuel pressure no matter how I drove. I also developed a leak at the fuel filter head where the water drain is. I never had pressure problems with the stock Carter or leaks as far as that goes. What method is used when rating these pumps?



After sleeping on it I decided today to try another inline pump. It is like the one I have now except it is rated at 15PSI at 50GPH. I am hoping that by slowing down the volume pressure will drop off a little as well. Just for safety measures I ordered a Mallory fuel pressure regulator. It is a three port regulator and I assume that the third port could be tapped in to the fuel return line on the truck. Can anyone confirm this?



At any rate, I think what has been proven with my testing so far is that one pump is more than sufficient. I hope to come up with the right combination by weeks end. The real test will be how long a pump of this design will hold up. I hope to figure out how to post some pictures as well.

 

[Un-Hemi]

I am concerned that the same part number (512-105) is listed as both a 15psi pump for TBI systems, and also as a 45psi pump for MPFI systems. Does this mean that it is capable of producing 45psi????? Is it available in two versions? Why, then, only one part number?????? I have an email into Holley for clarification now.



CannonBall, if I were in your position, I'd stick a mechanical fuel pressure guage on your system just to verify that the pressures you think you are seeing are actual. Not all electric fuel pressure gauges have the same calibration or sender resistance. You may actually have much more pressure (or less) than you think you do. I'm just a big skeptic at heart!

 

[CannonBall]

Tommy, let me know what you find out from Holley. I think the mechanical fuel pressure gauge is a great idea also. I will pick up a gauge with some fittings tomorrow and compare readings to my electric gauge. The new pump I ordered should be here Wendsday.

 

[Un-Hemi]

Yikes! Here's the reply from Holley... .



"that pump can be used as either, it will depend on the style regulator you are running. "



I take it to mean that the pump is running AT LEAST 45 PSI and must be regulated to whatever you want. CannonBall, ya better get that regulator in there or that pump outa there! No wonder your filter is leaking and the engine's hard to start.



I've requested more information from Holley about regulator requirements; I'll post their reply.



Tom.

 

[CannonBall]

Tommy, this pump is used with a throttle body injection kit. Generally the throttle body's run lower pressures than multi port. I put an Edlebrock Pro Flo system on a stroker engine and the pump it came with was a Walbro inline style pump and that thing cranked. Very loud pump. Rated at 50 PSI.



I have also spoke with several people from Jeg's and two Holley techs and they confirmed this is a 15 PSI pump. Very strange. Right now my truck is sitting and will continue to do so until I get all this sorted out. My new pump and regulator should be here tomorrow.



In the meantime I am going to get on the Holley tech line and see what I can find out. Maybe this is why I was able to run 110MPH uphill with 32 pounds boost and the fuel pressure never budged.