Archived lift pump replacement

[bradyw]

I replaced my lift pump to day and when i was done went to prime and took for ever and no fuel out bleeder on filter so i read up on primming in here and a couple of guys talked about putting pressure in the tank to prime system i tried this and it started to bubble a little and now i can hear the tank expand a little is there a valve in there or some thing it like i cant draw any fuel at all ran fine this morning other than low fuel pressure i need the truck tomorrow pls any info thankx

 

[Missouri Mule]

There is a pressure relief/roll over valve in the tank connected to the tank vent which is on top of tank module.



On the bleeder screw. Which one did you crack open, supply line to filter or supply line to injector pump?

 

[bradyw]

I got it primed finally my daughter was helping me and wasnt keeping pressure in the tank but still only have about 15 or16 psi fuel pressure changed the overflow valve also went with the tek adjustable one and lift pump from larry b's just changed the fuel filter and cleaned the prefilter could the filter in the tank cause this much restriction im checking pressure with a mechanical gauge. Now it isnt jumping and it read 2or3 psi till i changed the overflow valve. Let me know if i need to move to the regular forum thanks guys. I was using the bleeder on the injection pump side

 

[Missouri Mule]

Yes the screen on the tank module could cause restriction. Are sure the pump is rated for higher pressure? Gauge working correctly? Have you tried revving engine up to 2000 rpm to see if fuel pressure rises? Fuel pressure at idle should be no less then 20 psi but 25 or higher is better when you rev it should go to at least 30 psi.



I use the supply to filter banjo bolt to bleed until I see no air bubbles, cose it then I prime it about 30 times or until i hear the overvflow valve opening and closing.

 

[bradyw]

My pressure didnt change when i reved it up thats why i think its got to be a restriction in the tank plus it took alot of pressure in the tank to get it primed? What do u think? going to pull sending unit and see soon. It does run alittle stronger but still about half pedal which makes me think pressure reading is right.

 

[Missouri Mule]

Question on the adjustable overflow valve, was it preset to a certain pressure (pressure that it opens) and/or did you adjust it.



Stock overflow valves open at aprox. 22 psi. So yours should be opening at 22 or higher psi.

 

[bradyw]

It was suppose to be set to stock spec i never touched it. I had hell priming it. Iv been told 18to 20 idle and around 30 at 2200rpm the pressure seems more steady i wonder if the tank filter has been pluged for a while and thats why lift pump got week now its the same no matter the rpm wich was the max the other lift pump would do at 2200rpm wich make me think thats all it can get through the sreen filter in the pick up. thanks for the help and ideas does that sound logical or not

 

[Missouri Mule]

Yes the screen in the tank can get plugged and tank could be full of junk.



Try this when truck is idling squeeze rubber return line with pliers see if pressure goes up or stays where it is at.



If it goes up problems with over flow valve. If doesn't go up or goes up slowly lift pump(mite be cause by filter in tank).

 

[bradyw]

Heres the newest. I got my module out and the screens were good the tank was clean. So what next why with the new lift pump, overflow valve, newer fuel filter, and cleaned pre strainer and still low power and only 17 or 18 psi. I guess ill put all new lines from the tank to pre strainer and overflow back any ideas.

 

[Missouri Mule]

bradyw, IIRC I have read a few threads that some of these adjustable overflow valves are not set right ( that is why I suggested to squeeze/pinch the return fuel line. If pressure goes up it's your overflow valve (probably just needs adjusting) if doesn't go up or goes up slowly lift pump or at least problem with fuel supply. )



Is the engine starting right away?

 

[hsmith]

bradyw, IIRC I have read a few threads that some of these adjustable overflow valves are not set right ( that is why I suggested to squeeze/pinch the return fuel line. If pressure goes up it's your overflow valve (probably just needs adjusting) if doesn't go up or goes up slowly lift pump or at least problem with fuel supply. )

Is the engine starting right away?

As Bill says, check the OFV. Mine out of the box was way out of adjustment with the jam nut loose. With it idleing turn it in slowly while watching the gauge. It should rise if there are no other issues. It sounds like you have covered most everything else.

 

[bradyw]

Yes it starts right away. Should i still run rubber fuel lines just too rule them out has anybody had a restiction in the line. Ill put it back together and check overflow valve then run fuel lines maybe?thankx for the help guys

 

[bradyw]

Ok heres what new again, put moduel back together and cleaned then reinstalled it started right up no priming. Bthen i went to the overflow valve. Before adjustment i had about 17 and after with valve bottomed out at first i got 29 but when i reved it up it dropped to 22 to 23 then after it warmed up it dropped to 26and when i reved it up 22 is this normal i dont want to put bed back on if i need new lines soni cant drive it and see how it feels till i put bed down. Just to throw it out there my gauge is from tractor supply psi liquid filled 100 psi

 

[Missouri Mule]

The pressures at idle are good but should not vary as far as I know. When you rev it pressure should go up!

I take it you are moving the adjusting screw downward or are you moving it upward? Can see the gauge while you are adjusting it?



Have you tried sqeezing rubber return line when at idle to see what the pressure reads?

 

[bradyw]

I will tomorrow. Going to put it together and drive it and see.

 

[BigPapa]

Have you tried sqeezing rubber return line when at idle to see what the pressure reads?

I would do this before driving. It has been suggested multiple times.



I don't understand why people ask for help and ignore it when given.

 

[bradyw]

"Finally" pinched off return hose and now at idle i have 22or23 when i pinch the hose psi drops 2or3

 

[bradyw]

It doesnt start supper fast maybe one to two rotations. Would a pinched metal line some where do this. I blew in to both lines on the moduel and they seemed clear. It runs a little better but still feels starved. I guess ill have too put new lines on it. I adjusted the overflow valve all the way in twords the pump only got five more psi. I did notice i need new throttle linkage does anybody have any part #s. I will go down my fuel lines along the frame tomorrow. Would a leak keep the pump from building pressure,has anyone had a pluged line? if its not the overflow valve what else could restrict flow my gauge is hooked in at the feed to injector pump on the pump. Thanks for the thoughts guys appreciate it.

 

[wcjp]

I didn't see in this thread if you have changed out the soft lines. They can dryrot. They will leak air into the system but, not fuel out of the system. On my 96', I swapped the fuel supply/return line with marine grade diesel line. The actual problem turned out to be the two separate problems. The fuel preheater assembly leaking air into the system. Replaced gaskets and strainer. The second and larger problem was the fuel preheater to liftpump soft line. At the time this soft line was on a long back order from Dodge. I ended up running a long soft line with a big loop to avoid kinks. It had to be a certain length to avoid a kink and to avoid rubbing on the steering shaft. I also used Marine grade soft line.

When removing the fuel supply/return soft lines. It helps to pull the starter. Of course this is now a good time to replace the starter contacts.

 

[bradyw]

So i guess changing all the fuel lines and removing the heater is all thats left would that air leak cause pump not to build pressure. thankx everybody