LPU_911

Hi, the PO of my truck bought a new lift pump to replace the old one but it "wasn't needed". What is the deal with the stock lift pump? Why do so many people replace them? DO they fail or are they just not capable of high performance?
He bought this pump from NAPA for about $150, seems like he got ripped off. How much do they usually sell for? I want to get a fuel pressure gauge to see how the original one is doing, but what should I do if it is in need of a replacement?
I could try an sell it on Ebay or install it I guess. What I'm really trying to ask is, if I need a new lift pump would I be better off getting an aftermarket one or installing this one which I have. Overall I am aiming for reliability. I don't plan on crazy amounts of horsepower or anything like that, just a little more than stock.

Jklawinsky

Their ok on a STOCK truck. I would recommend a 2nd gen low pressure lift pump if you don't plan on going to crazy with fuel. Reliable, mechanical, and they don't cost an arm and a leg.

BearKiller

LPU 911,

The original "stock" lift-pump is a standard diaphragm-style mechanical lift-pump, much like that found on just about every gas or diesel engine ever made prior to electronic fuel-injection.

In healthy condition, they run around 4- to 7-PSI fuel-pressure and deliver plenty of volume for even quite a bit of injection-pump tuning.

The drawbacks of the diaphragm pump are first the diaphragm, which, if ruptured, will pump fuel straight into the crank-case.

Secondly, the VE pump has an internal vane-pump and is well capable of drawing fuel through a dead diaphragm-lift-pump, with the driver being none the wiser; however, doing thus, there is not quite the high volume of cooling/lubing fuel being cycled through the return system.



There is nothing wrong with running a diaphragm lift-pump and, were I you, I would for certain hang onto that extra one.


Get one of these, or better yet two of them :

http://www.genosgarage.com/prodinfo....BF-LONG-TAPPED

It says for later model, but it FITS our engines.

These replace the banjo-bolts in the fuel-filter INLET and OUTLET and have a 1/8-NPT threaded hole to connect plumbing for a fuel-pressure gauge.

If only one gauge is used, put the banjo-bolt in the filter OUTLET; this will alert you to low fuel-pressure, meaning either the filter is stopping up or the lift-pump is weakening.

If you will use TWO gauges, one in the INLET and one in the OUTLET, you will know for certain whether a drop in pressure is the filter or elsewhere.

LPU_911

Wow, thanks for the great info. I'm on a fairly tight budget right now, do you highly recommend running two gauges? It seems to me, that, while helpful, the money could be better used elsewhere. If I was to run only one gauge and my lift pump ruptured, I would waste a fuel filter diagnosing the problem I guess.

BearKiller

To better understand what people are meaning when they talk of a "2nd Gen. lift-pump" or a piston-lift-pump, read through this excellent pictorial TECH article.

You will see pictures of the factory-issue diaphragm lift-pump and pictures of the "low-pressure" 3936320 piston-lift-pump.

The 3936320 is capable of a steady 15-PSI when coupled with all 3/8" DRAW-lines plus 3/8 rubber lines and JIC fittings replacing the factory hard-lines.

A piston-lift-pump has no diaphragm to rupture and spill fuel into the engine, nor can the VE draw fuel through it.

Enjoy :


https://www.dieseltruckresource.com/...ad.php?t=93722





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BearKiller

One fuel-pressure gauge is way better than no gauge at all.

The way to diagnose a ruptured diaphragm is to always smell the dipstick for diesel; if you always do this where others can see you, they will soon inquire as to what on earth you are doing and, upon hearing your reasoning, they will think you the smartest man alive.

Also, when the oil-level constantly gains on the dipstick, fuel is most likely getting in the oil.

LPU_911

Just finished reading that post, I will try and get my hands on one of those pumps, it would be good peace of mind. I am saving up and would like to get all my gauges at the same time since I will have to get them off the web. I was thinking, tach, fuel pressure, boost, and pyro.

Great tips on checking the engine oil, I will go ahead and do that. Is there a realistic chance of the pump slowly dying without rupturing the diaphragm? I am afraid that with how many miles are on it it might not be quite up to the task.

Jim Lane

I always wanted to outfit my truck with the ultimate in insturmention and use aircraft gauges

You could set up this gauge to read both pre and post filter.



http://www.aircraftspruce.com/menus/...ure_0fuel.html

Jim

BearKiller

I have also seen dual-needle mechanical gauges in big trucks.

The RED needle being one reading and the WHITE needle being the other.