Lift Pump ['96] Priming Question

[tomblue01]

It seems when enough pressure builds during a manual prime session, my LP begins to leak from the boot area. Is this normal?

 

[The patriot]

No.
Are you sure it's not the heater? If it hasnt been removed, it's a leak prone item.

 

[tomblue01]

Not the heater. Have checked. [& while I was avoiding diesel drops as I looked up, I noticed an unplugged cable - for the heater! {Thanks for informing me, PO!} Turns out that the ground pin had melted. All this time I thought it worked... *shakes head* Just couldn't see it well enough from above!]

 

[GAmes]

A stock lift pump is really two pumps, the one you hand pump and the one that is driven by the cam. If it is leaking from the boot it will not fix itself. New LP time.

 

[Timd32]

They have a decent write up under the install and tech tab.

Also has the longer studs included.

://www.genosgarage.com/product/pump-4988747-kit/fuel-pumps

 

[tomblue01]

The internet shows two LP's - the 30$ one and the 3x the cost of the cheap one. I'm pretty sure I have the cheap one, and it doesn't look that old at all. *sigh*

Working up an order for the premium one now.

 

[Missouri Mule]

Check Genos you should have the catalog. Genosgarage.com

 

[tomblue01]

Another Couple of Manual Prime Questions

Should I see an increase in fuel pressure when pushing the hand primer button after bleeding air from the system?

I just did my pre-heater delete. I have not removed the old LP yet. I have also installed a fuel pressure gauge on top of the fuel filter [Larry B's]. I attempted to bleed the system & start the truck. No love.

After cracking the banjo bolt on top of the fuel filter [fuel pressure gauge replaces that little 10mm bleed bolt], pushing the priming button scores of times, fuel comes out the top. While still pushing, although not near the previous rapid pace, I tighten the banjo bolt back up [it's a slow process because I can only get about 1/16th of a turn with my wrench [I wonder if a stubby would work better here?]]; I then crack the 19mm banjo bolt on the side of the IP; push the hand primer button again; after about 5-6 pushes fuel begins to run out; as it's flowing out, I tighten that banjo bolt up; I push the primer button about 20 more times. I notice that my fuel pressure gauge is not moving. [edit: removed a distracting part of the story.]

Does anyone have Larry B's setup? Can you see the gauge respond to the hand primer?

I'll save my other questions for later.

 

[The patriot]

You may want to bump the starter so that you get full stroke on the LP.
Yea, the bleed screw is in a tight spot.
It takes a while, I've resorted to stuffing an air hose wrapped in a rag in the fuel tank fill line.

 

[tomblue01]

After some consideration, I'd like to rephrase the question: Can one determine the health of the lift pump using a mechanical fuel pressure gauge?

Would someone with a known good LP & mech. ga. verify this, please?

 

[GAmes]

As I said before, the lift pump is two pumps in one, the one you prime with and the one that is actuated by the cam. So gauging it's health can only be done with the engine running. This has also been posted before, but is worth repeating.
http://www.cumminsforum.com/forum/94-98-engine/58777-joe-gs-fuel-system-writeup.html

As to your question, I can get almost 25 psi using the primer button , about what it sits at at idle.

 

[tomblue01]

So, pushing the hand primer on a working system does move the fuel pressure gauge! It may not be indicative of the engine/cam side of the LP, but it seems to point at the the manual prime side of LP.

I've read JoeG's write up. Sadlly, most of his images no longer display. Nonetheless, it's very informative. What I don't get - it seems counterintuitive - how does a system take in air but not leak diesel? [Edit: I believe the air pushes the fuel back into the tank, so there won't be a leak on the ground.] I don't have drops of fuel underneath the truck [once I stop priming and wipe everything up]. Somehow, still, I [recently] can't hold prime. I took an air compressor, set to 20psi & using a rubber stop in the fuel filler neck, and had someone hold pressure while i looked underneath at the feed line, pre-screen, 1/2" short elbow to the LP, & fuel filter. [If I'm not mistaken, this is your idea Mr. Ames.] I didn't find anything bubbling out. Pressure was held for about a minute.
I'm baffled.

Just out of curiosity & in an attempt to better understand my truck, has anyone else seen a pressure increase when pushing the primer button on perfectly good 12v?

 

[GAmes]

Without any pressure the cracks are not big enough for fuel to go through them, but under atmospheric pressure air can enter through suction of the interior. I gave up on trying to pressurizing the tank, IMO there is too much volume of fuel to move, so that isn't my idea. I disconnect the fuel line at the first fitting forward of the tank and add regulated air (15 psi) there. Air/fuel bubbles will show up, sometimes not easily. However, if there is a leak at the connection at the top of the tank, the only way to find that would be by pressurizing the tank at the filler. Depending on how much fuel is in the tank it might take more than 20 psi.

 

[The patriot]

After some consideration, I'd like to rephrase the question: Can one determine the health of the lift pump using a mechanical fuel pressure gauge?

Would someone with a known good LP & mech. ga. verify this, please?

Assuming the overflow valve is OK...yea....to a point.

 

[Woodenhead]

Assuming the overflow valve is OK...yea....to a point.

What he said^^
In my experience it's been the OFV that failed before the mechanical lift pump. Those pumps are one of the most reliable parts on these trucks.

 

[The patriot]

My LP was shot and I didnt know it.
Truck power was down, I thought I just got a crap load of fuel.
Next tank....same, and again.
OF valve is a Torq-tek, so that's fine.
Switched out the LP since it wasn't quite building pressure like it used to.....but still within spec. (with something like 80K miles on it)
Viola! Problem solved.

That's why I added the "sorta" in my last post.:-laf

 

[SSage]

I'm on my second replacement lift pump.

My OEM carter lift pump on my 1995 dually started leaking around 80K miles, but it was feeding the engine fine. I replaced it with a "Cummins" lift pump from Genos. It ran okay, but obviously the power was down, lower boost etc. I replaced all the seals, hoses etc with OEM where I could. It was good at starting quick, no leaks or air issues so I thought. After 10,000 miles the lift pump started failing, idle dropped, power was way down. The Cummins Chinese lift pump didn't last long at all, at 16,000 miles and 2 years it failed on me. I bought another Chinese pump, this time its the Cummins DCEC brand pump from Poormans, hopefully it will last longer. My current lift pump just says Cummins and "Made in China. New pump looks similar with a DCEC brand on it, Cummins logo on the box. My OFV was replaced a couple months ago, no change. I looked at everything else thinking the lift pump was "fresh" and a Cummins part. I wish I had looked at fuel pressure first! Get a fuel pressure gauge inside the truck.

 

[The patriot]

The "new part number" is 4988747 and it's made in China.
It has ABFJV or something like that cast into it.
It's supposed to have a slightly bigger bore than the old part number.
You can get them for about $110 on fleabay, and the Carters are about $70.
I actually have a couple genuine Cummins rebuild kits for the old part number.

 

[SSage]

The "new part number" is 4988747 and it's made in China.
It has ABFJV or something like that cast into it.
It's supposed to have a slightly bigger bore than the old part number.
You can get them for about $110 on fleabay, and the Carters are about $70.
I actually have a couple genuine Cummins rebuild kits for the old part number.

I have the 4988747 lift pump now, it's about $69/$70 shipped from Poor Man Diesel off eBay. I haven't installed it yet, hopefully it will work better than the last one from China. My 95 truck has been sitting for a couple months. Been busy working, haven't had enough time mess with it or maybe it's will power.

 

[Missouri Mule]

My orgnl lift pump went out around 250 - 270,000 miles. My overflow valve soon after.
375,000 now and they seem to be doing fine. ( lift pump genos/ cummins) , ofv Bosch.
Did you change out fuel filter recently?