hey all. i dont usually have any question on working on these engines, but today im a little puzzled. i changed the stock lift pump on my 2001 with a raptor 100. i had this lift pump on my other 2001, but i just got that one an air dog 150. 

anyhow, ive changed lift pumps/filters on these trucks 20+ times and have done the bleeding procedure as anyone would. crack lines 1,3,4 bump a couple times till you get some fuel, crank until air is gone and fuel is clear, close lines, start.

today after i got done finishing my lift pump install i did just as i stated and i was getting some fuel/air from all three. line 4 started to get good fuel and it was acting like it wanted to start. all the sudden lines 2 and 3 went from fuel/air bubbles to nothing. i cracked the vp44 line and was getting good fuel there. i then started to crank again and again with fuel only coming out of line 4 and not 1 or 3. i then opened line 5 and got good fuel from 4 and 5 still but none from 1 and 3. it isnt even trying to act like it wants to start. no engine codes. im guessing vp is toast. whats your thoughts. 

2 hours ago, dripley said:

I would check your fittings again on the suction side and be sure they are tight. It sounds like you are sucking air in somewhere with all the foamy fuel you are seeing.

i checked them all when i had the raptor on there and then obviously when putting the stock LP on i made sure it was all tight, but it does seem like air is somehow getting sucked up. 

I hope you don't have your lift pump hot wired when you're trying to start, you could probably hotwire it just to bleed the system, but when you're actually starting it you don't want full pressure maybe 6 7 PSI. Really if you have your system blead really well then you can just unplug power to lift pump to start.

Don’t give up youll find it don’t forget to check the filter housing top make sure it’s sealed properly think it has a o ring on it.. i bypassed mine for airdog 2 micron so been a few years since I messed with the original one sucks your having so much trouble always turns out to be something stupid I was sure I did when I have these problems..

6 hours ago, snoogett said:

Don’t give up youll find it don’t forget to check the filter housing top make sure it’s sealed properly think it has a o ring on it.. i bypassed mine for airdog 2 micron so been a few years since I messed with the original one sucks your having so much trouble always turns out to be something stupid I was sure I did when I have these problems..

thanks for the support. ya ive checked. thats one place where i have even bled multiple times. i really dont know what to do from here. i mean, is it possible that the vp is shot? only code i have is for an overboost, which i always get for some reason, i dont even boost above 20psi. 

1 hour ago, cumminsVP2001 said:

thanks for the support. ya ive checked. thats one place where i have even bled multiple times. i really dont know what to do from here. i mean, is it possible that the vp is shot? only code i have is for an overboost, which i always get for some reason, i dont even boost above 20psi. 

You must have a lite foot not to boost over 20 psi with the mods you have.

 

As far as the pump they can fail without a code but it is unusual. Did you ever try a shot of starter fluid?

On a class 8 truck I would give the fuel tank a little dose of shop air with the tank vents plugged which would give the fuel tank a little positive pressure which reveals fuel line leaks that cause the fuel pump to suck air.

 

There might be a way that you could pressurize the tank and try to bleed the air in the fuel system while looking for fuel leaks. I wouldn't go much over 3-4 psi of air in the fuel tank. Reading through this you state the fuel is foamy out of the VP which means you are sucking air before your lp or fuel level is below fuel pick up level.

Edited July 12, 20186 yr by 04Mach1

5 minutes ago, dripley said:

You must have a lite foot not to boost over 20 psi with the mods you have.

 

As far as the pump they can fail without a code but it is unusual. Did you ever try a shot of starter fluid?

lol no this isnt the truck in the description. this is my other 2001, its all stock... my baby in the description boosts 50-55

 

yes i did starter fluid. started the truck right up but unless i kept giving it a shot it would immediately die. 

4 minutes ago, 04Mach1 said:

On a class 8 truck I would give the fuel tank a little dose of shop air with the tank vents plugged which would give the fuel tank a little positive pressure which reveals fuel line leaks that cause the fuel pump to suck air.

 

There might be a way that you could pressurize the tank and try to bleed the air in the fuel system while looking for fuel leaks. I wouldn't go much over 3-4 psi of air in the fuel tank. Reading through this you state the fuel is foamy out of the VP which means you are sucking air before your lp or fuel level is below fuel pick up level.

thats the other thing is i literally have a tank on 'f' and if i bump the key or crank i dont get any leaking fuel anywhere if i close up the injector nuts

Edited July 12, 20186 yr by cumminsVP2001

10 minutes ago, cumminsVP2001 said:

lol no this isnt the truck in the description. this is my other 2001, its all stock... my baby in the description boosts 50-55

 

yes i did starter fluid. started the truck right up but unless i kept giving it a shot it would immediately die. 

thats the other thing is i literally have a tank on 'f' and if i bump the key or crank i dont get any leaking fuel anywhere if i close up the injector nuts

How much fuel line is between the fuel tank and the lift pump? The fuel line between lift pump and fuel tank is where you'll be sucking air.

Sucking leaks you will not see.  

So you have tried two vp44s and to lift pumps with the same results.  I wouldn't fool with them any more but look at hose, fittings and filter housing.  

 

Can you run a short fuel line from the fuel pump into a 1-2 gallon fuel can of diesel that's sitting up in the engine bay and try to start.  This way you by pass every thing but the lift pump, filter and vp44 and have the fuel gravity feed to the pump. 

47 minutes ago, 04Mach1 said:

How much fuel line is between the fuel tank and the lift pump? The fuel line between lift pump and fuel tank is where you'll be sucking air.

 

47 minutes ago, 04Mach1 said:

How much fuel line is between the fuel tank and the lift pump? The fuel line between lift pump and fuel tank is where you'll be sucking air.

but as it pulls fuel through the leak wont fuel come out?

11 minutes ago, cumminsVP2001 said:

but as it pulls fuel through the leak wont fuel come out?

No. It is sucking air. Negative pressure from the pump sucking the fuel. If you pressurize that line it would leak outward.

6 minutes ago, dripley said:

No. It is sucking air. Negative pressure from the pump sucking the fuel. If you pressurize that line it would leak outward.

aww i get it. i wasnt thinking.

32 minutes ago, IBMobile said:

So you have tried two vp44s and to lift pumps with the same results.  I wouldn't fool with them any more but look at hose, fittings and filter housing.  

 

Can you run a short fuel line from the fuel pump into a 1-2 gallon fuel can of diesel that's sitting up in the engine bay and try to start.  This way you by pass every thing but the lift pump, filter and vp44 and have the fuel gravity feed to the pump. 

i would have to get some kind of fitting that would attach into the back of the lift pump that has a barb so i can attach a hose

4 minutes ago, cumminsVP2001 said:

aww i get it. i wasnt thinking.

i would have to get some kind of fitting that would attach into the back of the lift pump that has a barb so i can attach a hose

Yeah air is lighter than liquid so with the negative pressure it will suck air first. The air is what is causing the foamy fuel. 

hey guys, been awhile. i havent even messed with the truck since we talked last. I was just sitting here wondering. would an easy option be to put a sump in with half inch line up to the raptor in the factory location. because if its sucking air it has to be between the tank and lift pump. 

I'm not a fan of sumps at all and some place are consider possibly illegal. I've been running a draw straw for years now and never had an air leak. I installed that straw back in 2006 its 2018 now but I'm running a full AirDog not a Raptor in the stock placement which is a poor pump in the first place and does not replace any of the small lines or quick disconnects.

2 hours ago, Mopar1973Man said:

I'm not a fan of sumps at all and some place are consider possibly illegal. I've been running a draw straw for years now and never had an air leak. I installed that straw back in 2006 its 2018 now but I'm running a full AirDog not a Raptor in the stock placement which is a poor pump in the first place and does not replace any of the small lines or quick disconnects.

why arent you a fan of sumps? other than you thinking they will get ripped off, which i would never have that problem. i know the raptor isnt great or replace any of the factory line, but you could definitely get a barb fitting that fits in the inlet side of raptor and run a line from the sump to the raptor. and a raptor is better than a stock carter pump

16 minutes ago, cumminsVP2001 said:

why arent you a fan of sumps?

 

Some state laws state that fuel can no be drawn from the bottom of a fuel tank. If sumps were legal concept then all modern diesel trucks would be outfitted with them. But they are not for a safety reason. Might check your local laws about bottom draw fuel tanks.

 

Some that most people won't admit to publicly is the huge hassle it is to replace a fuel tank after a sump has failed. I've talked to many people this has happened to. I've had people calling me asking where to find a factory fuel tank replacements because of failed sumps. 

 

Yes they can be ripped off I've found a few here locally that thought the same thing ruined the fuel tank and the sump both. Back to that topic of replacing the fuel tank. An again difficult problem to resolve.

 

Sumps do not guarantee a fix to an air leak problem. You can still have air leaks with a sump. 

 

 

Me, I am not cutting a hole in my tank for a sump. I have been pulling fuel from the basket for almost 17 years. In stock trim, in tank pump trim and AD trim. In all three they suck the tank dry. A sump is just as prone to suck air due to fuel slosh as any means outside the basket pick up method.

1 minute ago, dripley said:

Me, I am not cutting a hole in my tank for a sump. I have been pulling fuel from the basket for almost 17 years. In stock trim, in tank pump trim and AD trim. In all three they suck the tank dry. A sump is just as prone to suck air due to fuel slosh as any means outside the basket pick up method.

the thing im trying to avoid is dropping the tank to replace lines. im not trying to do that on the side of the road. i installed a sump on my truck in my signature and have had no problems and was a very easy install, thus why i asked