Engine/Transmission (1998.5 - 2002) Check valve for lift pump

[rowilson]

Hey guys I had a question. I know that the failure of most lift

pumps is due to the fact that they loose their prime and cavitate

because of it. Why not add a check valve in line near the fuel

tank to help keep this from happening? The fuel check valves

are relitively inexpensive and would help any truck I would

think. Ideas? Thoughts?

Thanks.

Rob

 

[rweis]

I fixed mine by puting a bypass regulator after the lp and set it to less than the lp bypass so the lp bypass should never operate / fail.



I set the bypass regulator to 12psi (pre filter), gives me 11 psi post filter. ROCK steady!



WOT 11 pre / 10 post. VP should be happy with 10-11 psi I think.



Bob Weis

 

[JTBMC]

Howdy Bob,

What regulator are you using and how and where is it installed. Do you have any photos of the installed unit.

Thanks, TJ

 

[rweis]

I used a Mallory 4307M. It is good for all race fuels so I think it will be ok for diesel.



I put it right after the lp (I have my lp on the frame) and before the OEM filter just in case anything should ever come out of the regulator. I bypassed it back to the tank "burp" line.



It is a very well made unit, easy to adjust, works in any position, mechanical regulator (no power, anything else needed).



Purchased at my local "real" auto parts dealer, about $110. You can find it cheaper on the internet, but I need the local parts store to stay in business as well, so I got mine there.



Prior to installing it I could see the pre and post fp fluxuate as the check valve opened and closed as the VP demand changed with driving conditions. Now it is rock steady.



Your lp valve spring is going to be different than mine so just set it so your check valve stays closed. I set mine at 12 psi.



I think it is easier on the lp as well because the head pressure of the lp is lower and the lp motor can spin more freely. The audible sound of my lp changed to a slightly lower pitch, which I take as to mean not working as hard. I did not measure the amperage difference of the motor before and after.



A side benefit is that when this lp goes I can put just about anything in its place because I can set the psi to the VP and not just take whatever the rated psi output of the new lp is. Maybe a 20 psi lp regulated down to 14psi.



Another side benefit to my system is I have a RACOR 690 filter pre lp. All the fuel bypassed back to the tank has been filtered and water seperated. There is a constant filtering of the tank contents going on at all times.



Works for me,



Bob Weis

 

[Walker]

Sounds simple......so,

couldn't this just replace an FASS type system (which I was thinking of purchasing, and) which costs a lot more? And does this totally cure the fueling/pressure problems of the LP and VP?



Maybe I'm not sure of the difference in the two set ups (performancly [really, it's a word] speaking).

 

[rweis]

I don't know about replacing the FASS. The FASS does other things. I think the FASS is a new pump, this is not. I think the FASS is a new filter, I did add a filter. I think the FASS is a bypass regulator, I did add a bypass regulator. I think the FASS does something about "taking the air out of the fuel", I did not approach that at all.



I wanted to use the OEM lp, read hunderds of threads of what the problems were, went about solving as many as I could, logically, cheaply, reliably.



Problems as I read them,

1. poor sucker - mount lp on the frame by the tank.

2. check valve fails - keep the check valve from operating - Mallory 4307M

3. nylon bushing fails - lower fuel pour point w/ Stanadyne Performance Formula (or like additive) add fuel heater to RACOR 690 (pre lp filter) so lp never sees "cold" unfiltered fuel.

4. lp motor just plain wears out - extend life by mounting lp on frame so it is below fuel in tank level in all but low fuel warning light cases (about 10 gallons remaining in tank), extend life by lowering head pressure (Mallory 4307M), extend life by adding lubricity to lp pump rotor parts (Stanadyne Performance Formula), extend life by removing any debris and all water prior to lp (RACOR 690).



And so I approached each problem and developed an integrated solution. Time will tell, but works for me.



Bob Weis