The only way I knew my primary was designed as a suction side filter was because the Cummins instructions gave a changing spec listed in Hg vacuum at the lift pump inlet.

 

Do you have any knowledge if the unit I am looking at is suction side or not? I don't see anything mentioned on the spec sheet I have for that thing.

Also, when folks delete the factory lift pump and go with an electric one, what do you do with the hole in the side of the block? Just make a plate to cover it? Also, what is the best electric lift pump to use in terms of both performance and reliability?

 

That unit needs to be on the pressure side.

A blockoff plate would be fine. I have mine plumbed in still so if the electric goes down the mechanical pump will get me home.

I like the Walbro pumps, plumbed with a bypass regulator after the filter. You WILL have fuel pressure until the filters are completely plugged.

 

What does the bypass regulator do and where do I get one?

 

The bypass regulator dumps the excess fuel back to the tank so you don't get too much fuel pressure.

Mine is from Glacier Diesel. It's just a simple relief valve teed into the feed line to the VE, it keeps me from having more than 18 psi at the pump inlet. The Walbro runs flat out all the time, meaning I have close to 100 psi available to shove fuel through the filter. Basically what this system does is prevent pressure drop across the filter from causing low fuel pressure unless the filter is completely clogged.

 

Ah, OK. Like the valve on my hot water heater. Wouldn't that cause a problem with the Racor unit? It says its maximum working pressure is 15 psi, letting the Walbro push on it with ~100 psi is several times the stated limit, wouldn't that "blow" my filters, or cause them to leak or something?

 

Yeah, it would not be compatible with that setup.

 

Hmm, OK. Is there any way to put a controller on it or something to keep it from building that much pressure, or is there a different filter manifold I should be looking at, or know of a pump that stays under the 15 psi limit?

 

If I was going to spend that kind of money on a filter setup, I would use a Davco primary on the suction side and a standard 3/4" filter head with a 2 micron Cat filter as the secondary on the pressure side.

 

Hmm, OK, that's an interesting setup, put 'em on both sides of the pump. So under your setup, I'd still use the pump you mentioned earlier? The Davco units look nice.

What do you think about putting a large, cheap filter in front of the Davco (screw in standard, maybe 30/50 micron) so that it catches all the big crap being the first filter in the line, thus reducing the need to replace the expensive, finer elements in the Davco. Do they make "normal" (aka cheap) filters that can go suction side? Like a Fram or some trash. You know, $10 throwaways.

Or are the elements in these not that expensive? I cannot seem to find any prices for them. I know the Racors, some of the elements were a couple of hundred bucks.

 

I think you are geting way too far down in weeds. If there's big chunks of anything in the fuel, the answer is to find a better place to buy fuel. Some of these trucks have gone a million miles with people running the stock filter (10um) and forgetting to change it for years at a time. Best setup if you really want to improve on that is a primary and secondary on either side of the pump, with a fine secondary on the pressure side. That in itself is probably overkill for these trucks.

Just be sure if you get really small (2um) the secondary is large enough or flows well enough to supply all the fuel you need.

 

Well, I never knowingly buy fuel from a place that is selling crap fuel. But I put 10,000 miles on my truck every 90 days so I cant buy fuel at the same place all the time, nor can I even stick to a single chain (though I always do try to buy from Flying J or Loves) and even in a chain that has good fuel there can be location-specific problems. Old underground tanks that allow water in, tanks with sludge in the bottom, ad nauseum. Getting a tank of bad fuel is a matter of time given my circumstances.

Its alot easier and cheaper to stop the problem it in the filters than it is to get it out of the IP. I can buy this entire filtration system, put it on and do half of the other modifications for what it would cost me to fix one bad fuel problem out on the road. I'd much rather go overkill than get myself stranded out in the middle of the desert, or sitting on the side of the road in Mexico or down and out somewhere on the Alcan Hwy. All of those places have seen my truck this year, and they'll probably see my truck again next year.

Its one thing to be broken down across town, or in the next town over, or even somewhere within your own state. There are inconvenient/annoying breakdowns and then there are potentially life threatening breakdowns. Its quite another to be broke down in another country or a couple of thousand miles from home where the nearest service place qualified to work on your truck may be 300 mile tow bill away and of course, your wallet will suffer from a severe case of rape by mechanic.

 

I use a 200 inline screen between the pressure filter and the VE as a last chance catch for big debris from a failed filter. Very uncommon, but it "could" happen. You just have to decide where to draw the line on practicality, cost vs. benefit.

 

Well, one of the benefits of the system Wanna talked about is the "Seeing is Believing" thing, it lets you see when the element (filter) needs changed based on when the fuel gets to the top of the filter. So stuff getting past the filters due to a failed filter will only be due to my negligence. As long as it becomes a part of the daily walk around inspection to fire it up and see where the fuel comes up to on the element, everything should be fine and dandy.

I am talking about putting a cheap, throwaway filter in front of the more expensive, higher quality filter to reduce the need to replace filter elements that I am sure run something like a couple of hundred bucks each. I e-mailed them asking for a price on the replacement elements, but they are closed for the holidays of course. If the elements are cheap, then its a non issue. But I don't like the idea of a $200 disposable element being my first line of defense, that could get expensive.

 

I can see when the filter needs changing on the fuel pressure gauge. You'll know something went horribly wrong going down the road is when the pressure drops suddenly and then the engine quits.