FP isolator, lift pump question
#1
FP isolator, lift pump question
I'm on my second lift pump. First new pump went on with a new fuel filter when I installed guages in February of 2003 and found pressures of 7 lbs. at idle, 5 lbs. at cruise and 0 lbs. at wot. In November of 2003, fuel pressure started jumping all over the place. At idle, it would fall from 13 to 5 to 10 to 1 and so on. I thought it was the lift pump and ordered another on from Cummins. I put the new pump on with a new fuel filter and had 13 1/2 lbs. at idle, 11 1/2 cruise and 10 lbs. wot. Now just a little over 3 months later, my numbers are dropping slowly. I'm seeing 12 lbs. at idle, 10 lbs. cruise and 8 lbs. wot.
Questions:
1) Was I right to assume the lift pump was bad in November of 2003 when pressure was jumping all over the place? What else could have caused the pressure to jump all over the place?
2) I have a rather large hydrolic hose running from the top of my fuel filter canister to the fuel pressure isolater that was supplied with my Dipricol guages. I had it made up at a local hydrolic shop. It's probably 1" in diameter. Should I get a smaller hydrolic hose like I see on other trucks? Would that make a difference in fuel pressure I see at the guage? Or should I get rid of the isolator and run a hose directly to the guage?
Thanks in advance, Mark
Questions:
1) Was I right to assume the lift pump was bad in November of 2003 when pressure was jumping all over the place? What else could have caused the pressure to jump all over the place?
2) I have a rather large hydrolic hose running from the top of my fuel filter canister to the fuel pressure isolater that was supplied with my Dipricol guages. I had it made up at a local hydrolic shop. It's probably 1" in diameter. Should I get a smaller hydrolic hose like I see on other trucks? Would that make a difference in fuel pressure I see at the guage? Or should I get rid of the isolator and run a hose directly to the guage?
Thanks in advance, Mark
#2
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I'd run the hose directly to the gauge. That will give you a slightly more accurate fp reading and now you know that if your pressures are still dropping, it has nothing to do w/ isolator malfunctioning. Ifdone properly, you shouldn't have to worry about fuel leaking into the cab. Sorry, I can't help you with the other q's.
Good luck,
Hunter
Good luck,
Hunter
#3
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can answer the first question but the larger diameter hose will give u quicker responce and should help to deaden randome fuel presure spikes. the smaller hoses make the guages bouncier. I dont know if u need a 1" line that may be over kill.
#5
I think I will run a hose directly to the guage. What do you all suggest? SS braided or something else? Where do I purchase a hose like this?
crobtex, I will take pictures and post later today.
crobtex, I will take pictures and post later today.
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I tried to post a picture of my Gemtop canopy for crobtex but it said my picture had too many bytes. The picture I'm trying to post is 128942 bytes. How do I make it smaller?
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#9
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Originally posted by MARKY MARK
I think I will run a hose directly to the guage. What do you all suggest? SS braided or something else? Where do I purchase a hose like this?
crobtex, I will take pictures and post later today.
I think I will run a hose directly to the guage. What do you all suggest? SS braided or something else? Where do I purchase a hose like this?
crobtex, I will take pictures and post later today.
#10
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I find using Windows Paint porgram is the easiest way to reduce pictures. The program is in most all Windows OS. You just shrink it by "percent", instead of trying to make a box or the pic smaller. After you reduce it, use "attributes" in the menu to check the size and reduce again if necessary. Be sure to save it where you can find it.
You can only post 500X500 pics.
CR
You can only post 500X500 pics.
CR
#15
Registered User
Originally posted by rattle_rattle
SS Braid looks cool but you don't need that much pressure rating. Any fuel rated material that will support the low pressure these LP puts out will work fine.
SS Braid looks cool but you don't need that much pressure rating. Any fuel rated material that will support the low pressure these LP puts out will work fine.
I use the same type 1/8'' tubing that's used for boost on both my trucks, working great for over five years. Installed the same on dozens of other trucks without a problem. I push the 1/8'' tubing though 1/4'' tubing to form a protective sheath, also makes the small tubing easier to work with, no kinking.
Any auto parts will have the tubing and fittings, often as a kit for mechanical oil pressure gauges.