Obs lift pump question

[OBS-Addiction97]

I’m wondering if the obs stock lift pump is capable of pulling through pre pump filters?

I did the tight wad mod on my work truck to delete the fuel bowl.

Two napa bases with a bf1212 and bf7633 right after selector valve.

Symptoms are sluggish until the truck warns up. I am running a wmo mixture for the time being- so this may be a cause. I read the obs lift pump is a 2 stage pump. I basically looped the line from the low pressure discharge to the high pressure intake on the pump.

 

[79jasper]

IMO, no. Especially not running waste oils.
Diaphragm pumps are notorious for failing when you put heavy filters before them.

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[OBS-Addiction97]

IMO, no. Especially not running waste oils.
Diaphragm pumps are notorious for failing when you put heavy filters before them.

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Copy, that’s kinda what I figured.

Guess my next project is to install a sd pump on it

 

[pdr60]

You need an electric pump from a 99-03 superduty. just frame mount it and be done with it. Very simple and best mod I've done on my 96.

 

[lincolnlocker]

Or even a carter electric pump as an actual lift pump between tank and filters.

Even stock, the factory valley pump in my opinion wasnt enough to pull and push through the stock filter.

 

[OBS-Addiction97]

I thought about a lift pump also, but I wasn’t sure if the factory valley pump could be pressurized or not.

I have a SD pump and all the fittings. Just have to install it.

 

[79jasper]

Do it then.....

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[OBS-Addiction97]

Do it then.....

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Just got the 7/8” freeze plug in today for the valley hole. Gonna do it this weekend.

 

[JohnT24]

Wouldn't you need a regulated return also?

 

[79jasper]

Yes and no. Could do the tightwad.

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[lincolnlocker]

I thought about a lift pump also, but I wasn’t sure if the factory valley pump could be pressurized or not.

I have a SD pump and all the fittings. Just have to install it.

Carter sells a low pressure high flow pump. I originally had that on whitey back in the day before injectors and hpop and the 5/8s draw straw days. After that i just went with the draw straw to a pre filter and to the factory fuel bowl with a riffraff regulated return then i modded the riffraff return to make a full on regulated return and still kept the factory fuel bowl. Never had a pressure issue running a walbro392.. only had 170/100s but still.

I wouldnt be afraid to keep the factory fuel bowl in tact and just bypass the valley fuel pump.

They sell the return kit that bolts right in the place of the old pump to utilize the factory return lines as well. Being everything is jic fittings and not the junk rubber bushing oring seal ****in thingys on a superduty 7.3 bowl, id totally do a electric pump. I totally would have used the obs fuel bowl and lines in the super duty as well.

 

[JohnT24]

Yes and no. Could do the tightwad.

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I see.

Years ago i bought the mark Fuga
E fuel block
Its uses the stock ford spring

Its been great.

Not sure if he still makes them

 

[Tiha]

Carter sells a low pressure high flow pump. I originally had that on whitey back in the day before injectors and hpop and the 5/8s draw straw days. After that i just went with the draw straw to a pre filter and to the factory fuel bowl with a riffraff regulated return then i modded the riffraff return to make a full on regulated return and still kept the factory fuel bowl. Never had a pressure issue running a walbro392.. only had 170/100s but still.

I wouldnt be afraid to keep the factory fuel bowl in tact and just bypass the valley fuel pump.

They sell the return kit that bolts right in the place of the old pump to utilize the factory return lines as well. Being everything is jic fittings and not the junk rubber bushing oring seal ****in thingys on a superduty 7.3 bowl, id totally do a electric pump. I totally would have used the obs fuel bowl and lines in the super duty as well.

What pump did you use? The SD pump work for this? Or how did the Carter compare to the SD pump?

I was thinking about doing an E-fuel but I don't mind my factory filter or fuel bowl with heater and sensors in it.

Was hoping I could use a SD pump and regulate the return. Dump factory mechanical pump and regulator while keeping the factory fuel filter. Filter should handle the pressure despite what I read online. Common sense says it is handling the pressure now.

 

[lincolnlocker]

What pump did you use? The SD pump work for this? Or how did the Carter compare to the SD pump?

I was thinking about doing an E-fuel but I don't mind my factory filter or fuel bowl with heater and sensors in it.

Was hoping I could use a SD pump and regulate the return. Dump factory mechanical pump and regulator while keeping the factory fuel filter. Filter should handle the pressure despite what I read online. Common sense says it is handling the pressure now.

I used the carter as a lift pump to feed the factory bosch electric pump on my 2000 superduty.

You can do the same with your mechanical pump.

Or completely bypass your mechanical pump and use the superduty bosch electric pump. There are kits available. Driven diesel/strictly diesel sells one i think.

 

[OBS-Addiction97]

Wouldn't you need a regulated return also?

I did the tightwad mod and removed factory fuel bowl already.

My plans are to reuse factory Y fuel lines to an AN adapter.

I’ll get some pics up later for everyone. I’m gonna be in this all for about 300.00

 

[ghohouston]

You can always grab a whole super duty fuel system out of a junkyard or part out. I did e fuel on my 97 this way, and added one of those riff raff frx's. Stuff can be had for a fraction of what those ridiculous e fuel kits cost.

 

[OBS-Addiction97]

Got it all put back together today. Truck runs much better than it did with the factory lift pump.

 

[Tiha]

So here is a question I have not been able to find any kind of answer for.

Fuel pressure/supply VS MPG.

I am on a mechanical OEM pump. It works. I really have no issues and no real need to go away from it.
Running 180/0 injectors for years and always seems to do "OK" Of course I do not have a fuel pressure gauge in the cab because I don't want to know. LOL

BUT here is what I am wondering. In my Gas engines, a weak fuel pump creates worse MPG. Does that hold true for the 7.3 as well?

Running a dual tank EFI truck with a 5.8 you would often see 12mpg on one tank and 14mpg on the other. 12 mpg tank (front or rear) needed a new fuel pump and problem solved.

However the Gas engine is cruising at a much higher rpm and most likely requiring more fuel flow vs a diesel eking out torque at low cruising rpms.

 

[OBS-Addiction97]

I would say yes, same scenario for a diesel. If you had a clogged fuel filter it would negatively affect fuel mileage. Same would go for a weak pump
IMO. I’m going to test this theory now actually. My truck was getting crap fuel mileage with the stock lift pump and 175/146.

 

[lincolnlocker]

Got it all put back together today. Truck runs much better than it did with the factory lift pump.

Perfect!! Im sure it runs a lot better!

By chance have a parts list? I may need to do this to the obs dually im working on if it eats another factory valley pump..

I mean, im sure i can find everything. Just been a while since i played with the fuel system on the ole 7.3s other than just replacing parts.