Some May recall my previous problem with my Fuel pressure. Initially the thought was air in the lines. But now I think it's something to do with the air dog pump block area itself. It still could be a house in this area,i dunno. What I do know, is that the problem is stemming from this area.

 

Last night after work, I killed the batteries trying to get the truck to crank over. Luckily I had a guy to jump me.

 

On the first startup of the day, it cranks over no problem. Sits afterwards, then it becomes a problem. This has happened a few nights in a row now. But not bad enough like Last night.

 

I'll bump the starter to get the pump to cycle, and I can distinctly hear a whirring noise like it's not primed. But maybe after a few bumps it'll prime and the whir noise goes away, the pump changes in sound and Fuel pressure goes back up.

 

Mind you I get about 17psi, when it's not sounding primed. But when it gets primed, 20 to 22psi. I'm at a loss here, and tried calling air dog But they didn't answer. Probably called too late...

 

Any idea what it is? Could the fittings to the pump block be bad? If it happens again tonight, I'll record video of it to try and get it.

Injector o rings? The orange ones on the injectors?

I'm not entirely sure of the color as I've never done injectors or had mine out but from what I've read it made it seem pretty straight forward like "the O-rings on the injectors could cause fuel leaking back." Maybe I'm remembering it wrong but that's what I remember made sense to me.

Last night i replaced the water and fuel filters. There was a change in pump noise and sounded allot better. But this morning, it was the same old noise of the pump again. Still had a start issue. 

 

I have been doing a bump cycling and then during the second cycle, cranking over. It'll fire no problem. 

 

When i took the fuel filter off, there was a percolating noise. I'm wondering if i have a faulty tank vent. Causing vacuum in the system and sucking fuel back out of the lines into the tank. I think i will try and leave the cap off over night and see if releasing any vacuum is causing the problem. 

Might as well try that out, let us know what the results are.

No dice...

 

Even left the cap off on the way to work and it didn't make a difference...

 

You know it's getting bad when i have a dream last night, with Mike being up where i live and he helps me find my problem. In my dream it turned out to be the draw straw. So we took one from a person that was drinking a fountain soda and replaced it with that. 

 

:D ...can't even make this stuff up!

What fuel pressure reading are you getting at idle?

Do you have the big line kit?

Is there a clogged screen at the lift pump inlet?

Draw straw cut too long?

Fuel canister/ module screens clear and clean?

Factory fuel filter cap wrenched to 25 foot pounds, no cracks in the plastic top from using the square and not a big socket??

I use pipe insulation around an air nozzle stuffed down the fill neck with low low pressure to prime the fuel and then see how she starts, if different?

Overflow valve working proper or the return line 'T' on the back of the head leaking?

 

Sorry for all the homework and questions, but, trying to help boss.

2 hours ago, JAG1 said:

What fuel pressure reading are you getting at idle?

Do you have the big line kit?

Is there a clogged screen at the lift pump inlet?

Draw straw cut too long?

Fuel canister/ module screens clear and clean?

Factory fuel filter cap wrenched to 25 foot pounds, no cracks in the plastic top from using the square and not a big socket??

I use pipe insulation around an air nozzle stuffed down the fill neck with low low pressure to prime the fuel and then see how she starts, if different?

Overflow valve working proper or the return line 'T' on the back of the head leaking?

 

Sorry for all the homework and questions, but, trying to help boss.

 

20psi

 

Yes i have 1/2" line all the way to the vp44

 

Never seen a screen for the lift pump inlet?

 

Using a modified fuel basket kit from air dog

 

Don't have oem filter in line for fuel supply. 

 

Will try the pressurize method and see what i get. 

 

Will check overflow valve too 

 

Put a mirror in the back of the engine bay and didn't see any leaks anywhere. 

The old ADs had an inlet screen but your F/P is good at idle so probly not the issue.

 

Do you have a water sep filter?

 

Bad batch of fuel?

 

Injection lines and supply line tight on  the VP?

I replaced both filters recently and yes i have a water separator. 

 

This has been going on for longer than a tank of fuel...

 

I also recently took off the lines to emery cloth the tips going to the crossover tubes as i read that this can cause it. 

 

They're torqued to spec, and no leaks visible. 

 

I know i seem like I'm shooting you down with every idea, but i guess it just shows all of what I've been trying. 

While you may not have seen a leak at the back of the head, it is possible for air to get in and fuel not get out. If you still have the OE sealing washers on the back of the head change them. They are cheap. 

Just some idle thoughts, but could the VP be the source of the bleed back? You might try clamping off the line at the VP over night and see if the AD still has prime issues?

My Son`s old 99 was always a hard starter which left me suspecting the injection pump after trying everything else under the sun.

 

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8 hours ago, hex0rz said:

I replaced both filters recently and yes i have a water separator. 

 

This has been going on for longer than a tank of fuel...

 

I also recently took off the lines to emery cloth the tips going to the crossover tubes as i read that this can cause it. 

 

They're torqued to spec, and no leaks visible. 

 

I know i seem like I'm shooting you down with every idea, but i guess it just shows all of what I've been trying. 

I hope to be able to  help.

 

  I think you have an air leak in the lines so if you put low pressure to the tank a drip might show up along the lines somewhere.

 

btw, Eric at Vulcan told me not to use the quick connect hoses, that they leak air. Mine is 1/2'' solid lines and radiator type hose clamps. I think your problem is at the draw straw hose connection at the top of the module if you have the quick connect there.

 

I just watched the Air Dog fuel Module upgrade Video and that's what they used to connect to the Draw Straw. Eric says a big No for those type

Edited August 12, 20168 yr by JAG1

13 hours ago, dripley said:

While you may not have seen a leak at the back of the head, it is possible for air to get in and fuel not get out. If you still have the OE sealing washers on the back of the head change them. They are cheap. 

 

Who carries them?

9 hours ago, JAG1 said:

I hope to be able to  help.

 

  I think you have an air leak in the lines so if you put low pressure to the tank a drip might show up along the lines somewhere.

 

btw, Eric at Vulcan told me not to use the quick connect hoses, that they leak air. Mine is 1/2'' solid lines and radiator type hose clamps. I think your problem is at the draw straw hose connection at the top of the module if you have the quick connect there.

 

I just watched the Air Dog fuel Module upgrade Video and that's what they used to connect to the Draw Straw. Eric says a big No for those type

I need to just spend a whole day at talking the problem. Going from beginning to end really combing through. 

 

I've talked to Eric, but after the bucket test showed no difference, he wasn't able to help me further. I also converted the quick connects on the supply side to parker hose and push fittings to eliminate that from the equation. 

 

I'm gonna start over again and work from the tank up. I'll probably have to drop the tank as removing the bed isn't in the cards as it's just me. 

Vulcan or DAP should have them or most any diesel shop. I dont think they are uncommon at all.

Here's a link to Geno's that sells the washer you need for the banjo bolt at the back of the head

 

https://www.genosgarage.com/product/bf-3963983/gauge-related

Alright, got the banjo washers changed out. Dunno if it'll make a difference. 

 

I think I've got gremlins running around my truck. Last couple days been smelling diesel fuel. When i changed out the washers i noticed the tee looked wet and i also noticed the #2 injector line weeping fuel. I cleaned everything up by washing everything down and rinsing. Then ran that truck a little to get it hot enough to dry it out. 

 

While it was running, it took several minutes for a drop of fuel to buildup on the injector nut. It doesn't appear to be coming from the thread area but more between the nut and line!

 

I'm not sure if loosening it then torquing it back down will fix it or not. I dunno what my course of action is here on the injector line problem. Do i have to get a new line?

 

As for the fuel return tee, what seals does that take? O rings, square seals, or something else? Been reading up on it and someone used 1/4" fuel line for a seal?

Edited August 20, 20168 yr by hex0rz

The threads on the injector nut do not actually seal anything. They hold the injector line to the cross over tube and the crossover tube in the head. The seal is between the injector line and the crossover tube. That joint needs to be nice a clean. I have always cleaned mine up with a scotch brite when ever I had the off. Still have had some leaking issues before. Loosening a re tightening has worked, re cleaning has worked, super torqueing has worked. Never found any cut dry method that worked for me just kept messing with it till it stopped. The line could be damaged. You would have to pull and see. It does not seem to be a common problem.

 

The return tee does take grommets. They are like a piece of rubber hose or fuel line. Squared edged and maybe 3/8" long. The fit in the tee and the return line into them then the nut just compresses them together to form a seal. Genos has them. You can find the part number in the parts look up tool in the articles section. I think they are pretty pricey for what they are.

@hex0rz here's a run down of the fuel tee fix 

 

Have you happened to check the ball on the return side of your Airdog?

Ball? What ball?

So it does look like i can use a piece of fuel line to replace them with. I'll have to try and verify size. 

 

Next step, fuel tee... if that works im going to be happy but also very mad, lol. 

I wonder, if the #2 line doesn't seal, can i purchase the individual line?

Pretty sure you can purchase individual fuel lines. Can't remember what site, but I'd check DAP, Vulcan or maybe thoroughbred.

 

Hmm, I assumed all these pumps ran pretty much the same but it looks like the AirdogII system doesn't use what I was referring too.