Well I thought the truck was running good... It sat last night and most of today and I went to start her and she fired first crank but idle extremely erratic and had a nasty lope and unloaded a mass cloud of white smoke... New injectors went in a week and a half ago and all seemed well until the lift pump failed. I'm thinking the LP took the VP too. Fuel pressure went straight to 20 psi so that's not a issue. Ran the key trick and got P1693 and then -------- and then P Done. checked for codes and found nothing. 

5 minutes ago, trreed said:

I had an issue like that once.  Could never figure it out, until I replaced the water separator.  Fixed it and the pump ran normally from then on.

I had an issue like that once.  Could never figure it out, until I replaced the water separator.  Fixed it and the pump ran normally from then on.

I had an issue like that once.  Could never figure it out, until I replaced the water separator.  Fixed it and the pump ran normally from then on.

I’m going to try to change filter and water separator but I doubt it’s gonna do anything. As @notlimah said being the issue is only when the trucks warm it’s harldly possible that it is air in fuel. Although there could be both bad vp and air in fuel 

5 minutes ago, trreed said:

I had an issue like that once.  Could never figure it out, until I replaced the water separator.  Fixed it and the pump ran normally from then on.

I had an issue like that once.  Could never figure it out, until I replaced the water separator.  Fixed it and the pump ran normally from then on.

I had an issue like that once.  Could never figure it out, until I replaced the water separator.  Fixed it and the pump ran normally from then on.

I’m going to try to change filter and water separator but I doubt it’s gonna do anything. As @notlimah said being the issue is only when the trucks warm it’s harldly possible that it is air in fuel. Although there could be both bad vp and air in fuel 

5 minutes ago, trreed said:

I had an issue like that once.  Could never figure it out, until I replaced the water separator.  Fixed it and the pump ran normally from then on.

I had an issue like that once.  Could never figure it out, until I replaced the water separator.  Fixed it and the pump ran normally from then on.

I had an issue like that once.  Could never figure it out, until I replaced the water separator.  Fixed it and the pump ran normally from then on.

I’m going to try to change filter and water separator but I doubt it’s gonna do anything. As @notlimah said being the issue is only when the trucks warm it’s harldly possible that it is air in fuel. Although there could be both bad vp and air in fuel 

Replacing the filters should take care of the fass sounding like a rock tumbler.  It should purr smoothly.

3 minutes ago, trreed said:

Replacing the filters should take care of the fass sounding like a rock tumbler.  It should purr smoothly.

Good I’d like it to be like that! That still don’t fix my issues though.... any other thoughts before I blow the cash on a new vp?

What your hearing is air coming through the system. Suction side is drawing air. Air is not dealt with till it hits the filter then the air is pushed out on the return line. So I would look at that fancy push to connect fitting you used on the stock pickup assembly. Again suction side line will not leak outwards. Not to mention I would highly suggest converting over to a full draw straw and using strictly JIC / Parker Pushlock fittings. 

5 minutes ago, Mopar1973Man said:

What your hearing is air coming through the system. Suction side is drawing air. Air is not dealt with till it hits the filter then the air is pushed out on the return line. So I would look at that fancy push to connect fitting you used on the stock pickup assembly. Again suction side line will not leak outwards. Not to mention I would highly suggest converting over to a full draw straw and using strictly JIC / Parker Pushlock fittings. 

That fancy push to connect was looked over last night and all seemed well. As stated already I went over all the connections and fittings in the system and thread taped and tightened them all. Can someone shed light on why it would only run crummy after it’s warm and not while it’s cold if the issue is air in fuel?

Thicker fuel will seal out the air leak. As the fuel warms up gets thinner it will leak air. 

 

Try a trick. Pull that suction fitting on the sender and get some thick grease and grease the pickup tube fitting. Now snap it back together. Now pack a bit more grease in the groove on the fitting. If the problem goes away you've found your air leak. This is only a temporary fix it will return. This means you end up changing to a full draw straw and JIC fittings. 

 

Rather common issue...

10 minutes ago, Mopar1973Man said:

Thicker fuel will seal out the air leak. As the fuel warms up gets thinner it will leak air. 

 

Try a trick. Pull that suction fitting on the sender and get some thick grease and grease the pickup tube fitting. Now snap it back together. Now pack a bit more grease in the groove on the fitting. If the problem goes away you've found your air leak. This is only a temporary fix it will return. This means you end up changing to a full draw straw and JIC fittings. 

 

Rather common issue...

I would really like to keep the pickup tube stock if at all possible. Someone mentioned not using the push to connect fitting and just pushing the hose over the suction tube and clamping it. Will that lock out he air?

@Mopar1973Man could I just pack it on without taking it off so I only have to take everything apart again? It will that not get the desired results? 

You can feel up there and get the connector off without taking the bed off.  A small set of needle nose pliers will help

Just now, trreed said:

You can feel up there and get the connector off without taking the bed off.  A small set of needle nose pliers will help

 

37 minutes ago, Mopar1973Man said:

Thicker fuel will seal out the air leak. As the fuel warms up gets thinner it will leak air. 

 

Try a trick. Pull that suction fitting on the sender and get some thick grease and grease the pickup tube fitting. Now snap it back together. Now pack a bit more grease in the groove on the fitting. If the problem goes away you've found your air leak. This is only a temporary fix it will return. This means you end up changing to a full draw straw and JIC fittings. 

 

Rather common issue...

Thanks guys I’ll try this tonight. And hope it works!! And Mike which draw straw do you recommend from Vulcan?

Most go for in the basket draw straw. 

Removed this post.  Browser didn't load this 5th page.  I like the idea of packing the quick connect with grease to validate that connection.  And no you can't just put your 1/2" hose on a 3/8" barb and expect it so seal at all.

Edited March 15, 20187 yr by Shainer

Can the air in my fuel be causing the low mpgs? I’m pretty sure it goes down farther every time I drive it! 

 Diesels operate on high pressure fuel injected at specific times and durations.  Air is not fuel.  In addition air is not a lubricant... I'd be taking this pretty seriously and getting after it.

Why not pressurize the system from the VP fitting and see where the leak is coming from?  Takes like 30 minutes. 

5 minutes ago, trreed said:

Why not pressurize the system from the VP fitting and see where the leak is coming from?  Takes like 30 minutes. 

By all means tell me more how do I do this? 

I got the grease on the fitting but I haven’t drove the truck yet I will be driving t in about  2 hrs. @Shainer I’m taking it absolutely seriously! Doing everything I can to find the problem! I’m goin to grab a clear hose if the hardware store or napa has one this afternoon after work. We should easily be able to tell if there is air in the fuel then. Mike mentioned elsewhere that I could start the truck shut it off and put the blower end of a shop vac in the filter neck and pressurize it and leaks would them show. Good Idea?? I do appreciate the help guys!! 

Edited March 15, 20187 yr by Marcus2000monster

I thought suction side WOULD show leaks as it's under actual pressure, where as the return side would NOT show leaks. Unless your leak is in the fuel basket fittings somewhere, I think you'd see if it were leaking. I still think this is more VP related then air in fuel related. There's tons of threads out there of guys having crap mileage and hard starting when warm and it's the VP.

5 minutes ago, notlimah said:

I thought suction side WOULD show leaks as it's under actual pressure, where as the return side would NOT show leaks. Unless your leak is in the fuel basket fittings somewhere, I think you'd see if it were leaking. I still think this is more VP related then air in fuel related. There's tons of threads out there of guys having crap mileage and hard starting when warm and it's the VP.

It never starts hard. It only IDLES like crap when warm. Also it never used to lope when releasing the clutch and it does that now warm or cold. The clear hose is going to tell me if there is air in the fuel. If there’s not I’ll suspect the VP44. Obviously I want to try the cheaper options first and work up to the Vp44. I’m ready to replace it if I have to but not if I don’t have to.

Edited March 15, 20187 yr by Marcus2000monster

I test systems as they function.  Half of the low pressure system operates in varying degrees of vacuum.  Pressurizing may not yield valid results.  Second is how does the FASS pressure regulator, bypass and return work?  Pressurize from the VP back... will that actually send pressure to the tank via the suction line, bypass line, both, or deadhead at the regulator?  I don't know that answer.  You packed the quick connect with grease.  Run it!  If it improves well you found the issue, and you don't need clear line or anything else other than fix that connection or replace the entire assembly with a draw straw.

2 minutes ago, Shainer said:

I test systems as they function.  Half of the low pressure system operates in varying degrees of vacuum.  Pressurizing may not yield valid results.  Second is how does the FASS pressure regulator, bypass and return work?  Pressurize from the VP back... will that actually send pressure to the tank via the suction line, bypass line, both, or deadhead at the regulator?  I don't know that answer.  You packed the quick connect with grease.  Run it!  If it improves well you found the issue, and you don't need clear line or anything else other than fix that connection or replace the entire assembly with a draw straw.

How did you pressurize at the Vp44? Air hose?

@notlimah Did you check out the video of what the truck is doing that I posted?

1 hour ago, trreed said:

Why not pressurize the system from the VP fitting and see where the leak is coming from?  Takes like 30 minutes. 

Will that work going back thru the pump? I don't know just asking. Almost sounds to easy.

Edited March 15, 20187 yr by dripley