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Gregturley

Mechanical lift pump

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On 6/24/2019 at 9:10 PM, IBMobile said:

One reason the fuel pumps are in or near the fuel tank is not because its pushing the fuel but rather it's pressurizing the fuel in the lines to keep the fuel from boiling and causing vapor lock.

 

Correct. When you place a liquid or fuel in a vacuum state then the boiling point goes down even lower. This is why long suction lines for either diesel or gasoline is a bad idea. When a fuel is place into a pressure state then the boiling point rises. Hence why vapor locking no longer happens with gasoline engine at 40 to 60 PSI of injector pressure from the fuel tank to the rail. :wink: Compared to fuel pump on a the side of block and the entire run of the steel line is in mild vacuum state and the boiling point is reduced too low and the vapor locking start early. 

 

Just remember vacuum is what we use to remove water from A/C system because it will cause water to boil at a very low temperature like 70*F. Just like the coolant system a 16 PSI cap help to raise the boiling point of water up above 212*F with coolant it rises even more.

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Serious question.. Has anyone here ever had vapor lock on a diesel? I'm not talking about "I ran my diesel dry now it wont start" situations. I haven't but I've only owned 2. I've been a mechanic 28 years and never ran across it. Don't know anyone that has. I have come across bad and weak pumps on diesels but most my career has been working on gas engine vehicles. 

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Posted (edited)

I've seen where conditions were right and reduced power and kind not are strong. Hard telling if its a suction air leak or was it the steel lines next to the hot exhaust. Never has a hard start. Only occurred when it was hot out and pushing the fire truck hard up hill to the fire. Fine on cooler day and not pushing hard.

Edited by Mopar1973Man
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Posted (edited)
On 6/23/2019 at 8:31 AM, Mopar1973Man said:

 

Strange that FASS and AirDog both put pre-filters on and causes no strain on the pump. Is the might mechanical pump that weak because it nearly double the distance from the fuel tank now at the very front bumper? Hmmm... Pumps are not design to suck or pull fuel long distance they are designed to PUSH fuel. This is where the weakness is being the pump must be located at the crank and adding huge distance from the fuel tank and forcing the pump to pull fuel longer distances and add a prefilter would impact the pump performance. Yeah this is basic pumps 101. The suction side of the pump should be as short as possible.

 

And yet FASS and AirDog still have a pretty high failure rate (from my reading on the diesel forums) Haven't they both been redesigned a few times now in the last 10 years? Different motors, and revisions, etc. Hmmmmm, not as reliable as they once were. 

 

I had a old school FP100 air dog on one of my trucks back in 2006 to 2012, put 200k on that truck with the FP100, never one issue. I almost put a FP100 on my current truck, but after reading all the problems people were having with the air dogs back in 2012-ish on the forums, and after reading some revisions that air dog went through, I decided I didn't want to rely on a electric pump anymore, and I went with a fuel boss. I have zero regrets.  

 

My current truck has had a glacier diesel fuel boss, on it for 230k. It's hardly what I would call weak. It's simple and it flat works. It does not matter that it's mounted at the front of the truck. Fuel boss moves plenty of fuel. The bypass can be shimmed if you want it to pop off at different pressures.  I'm positive it will be on the truck for as long as the truck is alive. 

 

2nd gen trucks don't need the over filtered fuel like the 3rd gen common rail trucks do. Nothing wrong with a strainer between the tank and the fuel boss, and filter between the fuel boss and VP44. IMHO air dogs and FASS are over kill for filtering on a 2nd gen truck.  

 

 

On 6/20/2019 at 5:23 PM, Welcometmnm said:

Probably not a bad idea for a strainer. When I cut into the fuel fill hose, the inside was like it delaminated. 

 

Cut the fuel hose with a brand new sharp utility knife blade, or a set of shears. Then blow the hose out with compressed air afterwards, to make sure no chunks are left in the hose. 

 

This is bug catcher I run on my truck. 

 

https://www.glacierdieselpower.com/i-1140-fleetguard-ff5079-3-8-inline-strainer.html?ref=category:169

 

I have it mounted on the frame near the t-case. So it is between the fuel boss and the tank. 

 

Then I have one of these, between the fuel boss and the VP44.

 

https://www.glacierdieselpower.com/i-1224-98-5-02-dodge-ram-gdp-mk-10-big-line-kit-non-heated.html

 

It's simple and it works. 

 

 

On 6/23/2019 at 8:31 AM, Mopar1973Man said:

 

Strange that FASS and AirDog both put pre-filters on and causes no strain on the pump. Is the might mechanical pump that weak because it nearly double the distance from the fuel tank now at the very front bumper? Hmmm... Pumps are not design to suck or pull fuel long distance they are designed to PUSH fuel. This is where the weakness is being the pump must be located at the crank and adding huge distance from the fuel tank and forcing the pump to pull fuel longer distances and add a prefilter would impact the pump performance. Yeah this is basic pumps 101. The suction side of the pump should be as short as possible.

 

Further more, 1989-1998 12 valve trucks have mechanical lift pumps mounted on the block far away from the tank, PULLING fuel. Not but 30 inches of difference between the side of the block and front of the bumper. How often do we here about those pumps failing on 1989 to 1998 trucks? Almost never. 

 

I've owned five 1989-1998 12 valve trucks, I've logged well over million miles on those trucks combined. Never replaced a lift pump on any of them. Pulling fuel far away from the tank. 

 

IMHO if dodge/cummins would have kept the mechanical lift pumps on the 1998.5 to 2002 trucks, pumping, PULLING fuel to the VP44, instead of going to the problematic electric lift pumps like they did, all of these aftermarket companies like, FASS, Air dog, and yes fuel boss, would never of had the need to reinvent the wheel. 

Edited by 24Vdodge

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Posted (edited)
3 hours ago, 24Vdodge said:

 

And yet FASS and AirDog still have a pretty high failure rate (from my reading on the diesel forums) Haven't they both been redesigned a few times now in the last 10 years?

 

4G AirDog is a good pump. Just don't want anything to do with the 3G pumps those are the ones with serious issues. My old 2G pump ran for a very long time before failure. 

 

3 hours ago, 24Vdodge said:

Further more, 1989-1998 12 valve trucks have mechanical lift pumps mounted on the block far away from the tank, PULLING fuel. Not but 30 inches of difference between the side of the block and front of the bumper. How often do we here about those pumps failing on 1989 to 1998 trucks? Almost never.

 

I've replaced plenty. Diaphragm fails and the fuel starts pumping fuel into the crankcase. Another common is person changes a fuel filter or runs out of fuel and the primer lever is broken change the fuel pump to get it started. Not to mention the VE didn't require much pressure (about 6 PSI) or volume. (no high volume return). 

 

Edited by Mopar1973Man
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12 hours ago, Mopar1973Man said:

 

4G AirDog is a good pump. Just don't want anything to do with the 3G pumps those are the ones with serious issues. My old 2G pump ran for a very long time before failure. 

 

 

Good info to know, for the future! I would not be opposed to air dog on my next 2nd gen truck if they are more reliable again now. I did like the smoother idle my other truck seemed to have, with a air dog, think it had to do with the whole intrained air separation thing they do. 

 

 

12 hours ago, Mopar1973Man said:

 

I've replaced plenty. Diaphragm fails and the fuel starts pumping fuel into the crankcase. Another common is person changes a fuel filter or runs out of fuel and the primer lever is broken change the fuel pump to get it started. Not to mention the VE didn't require much pressure (about 6 PSI) or volume. (no high volume return). 

 

 

I've heard of people breaking those priming levers, I never did thou, but then again I never used them ever.

 

Whenever I change a filter, I fill the filter up with fuel, over fill a little even, spin it on, or drop it in canister, wipe off the access fuel, start truck. Never had the need to prime them when doing it that way. 

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4 minutes ago, 24Vdodge said:

Whenever I change a filter, I fill the filter up with fuel, over fill a little even, spin it on, or drop it in canister, wipe off the access fuel, start truck. Never had the need to prime them when doing it that way. 

 

I never fill the filter with canned diesel it dirty fuel and unfiltered. That is the first thing to the injection pump. I always work the primer lever or the prime cycle on the key to fill the filter back up. 

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17 hours ago, Mopar1973Man said:

 

I never fill the filter with canned diesel it dirty fuel and unfiltered. That is the first thing to the injection pump. I always work the primer lever or the prime cycle on the key to fill the filter back up. 

 

Cummins mechanic taught me to do that 25 years ago, he said they always have a 5 gallon can of fresh fuel in the shop for when they change filters.  Saves wear & tear on the starter, and you don't have to stroke that lever dozens of times, save all that pumping & stroking, for when you get home he told me. 

 

I remember asking him about it not being filtered fuel?  He said stop and think about what you just asked me, any fuel coming out the output line of the "filter" going to the injection pump, will it be filtered...... filter. Run it threw a paint strainer if you are that concerned with it, he said. 

 

Good enough for certified cummins shop, good enough for me. 

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I always used the lift pump to fill mine. Just a short bump on the starter for 25 second run of the pump.

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19 minutes ago, 24Vdodge said:

I remember asking him about it not being filtered fuel?  He said stop and think about what you just asked me, any fuel coming out the output line of the "filter" going to the injection pump, will it be filtered...... filter. Run it threw a paint strainer if you are that concerned with it, he said. 

 

Good enough for certified cummins shop, good enough for me. 

Not if you're filling the filter through center hole, center hole is where fuel comes out to go to injection pump. You'd have to screw piece of pipe to keep fuel from going in center and prefill through smaller holes. Then you have to be sure pipe you screwing in isn't dropping shavings down the hole, and I don't trust any filters that don't come with plastic cover over the holes. Then it's a crapshoot either way. It's sad when first thing you do is blow garbage out of the hole. That goes for more expensive K&N filters, I seen cardboard and junk on the threads and down inside the filter. 

Best is to put filter on then prime the system with electric pump, even if the fuel looks clean the damaging particles cannot be seen with naked eye. So yeah most of us are getting lucky one way or another.

I quit changing filters at mileage interval, I look for pressure drop before I touch them now. I think changing them too often will bring more chances in putting particles in fuel system and causing more harm then good. The least amount of times I open fuel system the better. This is GMO. :2cents:

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Posted (edited)

Fuel filters are like oil filters anything poured into the center hole is unfiltered. This why I will not fill oil filter or a fuel filter before installing. Even though many shops still fill the filters before installing. It only takes a little bit of debris and it will do its harm to the engine or the injection pump. The only way you can fill a filter without the worry is fill through the side ring holes which is the filter inlet or don't fill it at all and use the pump to prime or priming lever. 

 

Even if you ask @AH64ID he will tell you the same thing. 

4 minutes ago, Dieselfuture said:

I quit changing filters at mileage interval, I look for pressure drop before I touch them now.

 

I have been getting 60k miles from my fuel filters now.

 

Edited by Mopar1973Man
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I understand what you guys are saying.

 

Knock on wood, I have only lost one injection pump, on the 8 dodge cummins trucks I've owned. I know for a fact, it was not because of the way I change my fuel filters. 

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Much to the chagrin of my two esteemed friends above, I do fill my fuel filters when changing them by pouring it straight into the filter. I cant believe that little bit of unfiltered fuel is going to wreck any thing. I used to do my oil filters that way too but just spin them on dry now. 

 

But to their credit I understand where they are coming from. We get to make our own choices.

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That is true life is full of choices, and we all do our best to make the right ones. What works for one might not work for the other you just never know. Used to know a guy that didn't believe in changing oil, he went like 60 k or more before he finally did change it, and it was only because I was over at his place and we were both bored at the time. Some just get away with whatever and others could do everything by the book and still have problems. 

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There is zero need to fill a fuel filter, as the lift pump will prime it. VP trucks are a little more forgiving than CR trucks, but still not something that's worth the 2 seconds you save. 

 

It's not the injection pump that gets the brunt of damage from unfiltered fuel, it's the injectors. 

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12 hours ago, Dieselfuture said:

That is true life is full of choices, and we all do our best to make the right ones. What works for one might not work for the other you just never know. Used to know a guy that didn't believe in changing oil, he went like 60 k or more before he finally did change it, and it was only because I was over at his place and we were both bored at the time. Some just get away with whatever and others could do everything by the book and still have problems. 

 

I know a guy that does that. Only changes his oil every 70-75k miles, but he does spin on a new filter and adds one quart of oil every 5k miles. His claim is, oil needs to be filtered, not changed every few thousand miles. 

 

Glad it seems to work for him. I wouldn't do it. 

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Posted (edited)
1 hour ago, 24Vdodge said:

 

I know a guy that does that. Only changes his oil every 70-75k miles, but he does spin on a new filter and adds one quart of oil every 5k miles. His claim is, oil needs to be filtered, not changed every few thousand miles. 

 

Glad it seems to work for him. I wouldn't do it. 

 

Member here on M73M which happens to be @dorkweed he ran his CR engine 80k plus miles on a single oil change on WalMart SuperTech 15w-40 and Fleetguard filters and a MotorGuard bypass filter. Was testing every 7k with blackstone and no issues till somewhere around 80k miles silicone was up from doing valve lash.

 

He did the same thing change filters and topped off.

 

Edited by Mopar1973Man

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12 hours ago, 24Vdodge said:

 

I know a guy that does that. Only changes his oil every 70-75k miles, but he does spin on a new filter and adds one quart of oil every 5k miles. His claim is, oil needs to be filtered, not changed every few thousand miles. 

 

Glad it seems to work for him. I wouldn't do it. 

That sounds like amsoil, which I suppose with quality oil and fine filtration should work fine. But I'm like you I'd rather change it every once in awhile to have a peace of mind. By the time you spent money on oil analysis you're almost there to change the oil. I suppose depends on driving conditions you could see what others get out of their oil life, and do half of that and you know you'll be safe then.

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