Engine/Transmission (1998.5 - 2002) Vulcan Draw Straw

[Fishin Guide]

A few months ago I set out to resolve a fuel supply issue I was having on my '02.



I am running a mechanical lift pump off a F1 camshaft. I was able to pull my WOT pressures down to 22 psi from 45 at cruise or idle. I was running a completely factory fuel system except for a piece of 3/8" line fro, the factory hard line to the new lift pump. Everything forward of the pump had been upgrading to -6 fittings and lines long ago to eliminate the banjo bolts. It was my guess that the factory oring connections at the module could possibly be leaking and I would start sucking air. There was just tons of vacuum on the system.



So, I started looking for a better mouse trap and asked questions on this and other boards about how to fix my issue. I wanted something cheap, but I would pay for a product that works. After being contacted by Eric at Vulcan, he started throwing some ideas at me to see if it work in my application. There were several generations of prototypes before Eric came up with a working unit and I installed it. At the same time, I upgraded to the -8 BIG DOG Fuel Line kit as well. This runs from the module to the lift pump. My idea was to reduce any intake restrictions in order to minimize aeration of the fuel.



I think I have the solution to my issue. I now have no less than 37 psi under WOT and still 45 at idle. I am working on a custom fuel bypass to regulate the pressure at the inlet of the VP as well. All it took was a little work and all is well. I had to drop the tank, change a remove and alter the fuel module, reinstall with Vulcan's parts and string a new feed line to the pump. I used the old factory feed hard line for a return. It only took a few hours and the results are obvious.



Also, in my '02 module, there are no less than 3 restrictions in the I. D. of the module of . 250" or smaller. No wonder I burned up 5 factory lift pumps!! I don't know what other years had the plastic fittings on top, but it's a worthwhile mod. Also, a buddy has a '99 that had a better design for a module, but he also could pull his FP down to around 20 PSI at WOT. Same pump, cam, ETC motor, Injectors and wheelbase as mine. He had similar results after the install.



So, thanks to Vulcan for coming up with a simple solution that does not require cutting bed crossmembers or using multiple module fittings. This thing was a breeze to install!!



Here's a link to Vulcan's site.



Vulcan Performance



I am one very pleased customer! And I imagine this could help the factory lift pump guys as well just by reducing restrictions. A small inline filter would be recommended. But the FASS guys already have that one covered.



Dave

 

[NoSeeUm]

Mine is already on the way.



Jim

 

[Fishin Guide]

Mine is already on the way.



Jim

My buddy says his fuel pressure regulator is responding quicker and helping maintain pressure.



Must be due to better control of pressure drop on the inlet side.



Dave

 

[NoSeeUm]

The pressure regulator is next on my list.



Jim

 

[OPoole]

If you looking to upgrade your cam the F1 cam and F1 lift pump kit is looking very strong!

 

[lsenus]

I too have received one of Vulcan's "Draw Stray" or "Super Sucker" pickup units. I have the -8 lines from the tank to the VP with the LP on the frame. 14. 2 idle, 13. 8 WOT.

The only problem I have is when there is less than 1/3 tank, I get fluctuating presures down to 12 psi. This is most probably due to the sloshing of fuel in these unbaffled, unsumped tanks of ours.



Time top drop the tank and install a sump box.

 

[Fishin Guide]

If you looking to upgrade your cam the F1 cam and F1 lift pump kit is looking very strong!

I have that one covered! :-laf



I even have a genuine OPoole hose kit from the pump forward. I was the one that got the custom machined pump nut and adapter. Ring any bells?



Since then, I have put in yet another F1 cam, changed to a little larger volume pump and upgraded the rest of the fuel system.



I should have a trick part for fuel regulation/ bypass in the next few weeks as well.



Dave

 

[GiesJ]

Dave -

I enjoy reading about the work you have put into your truck. Thanks.

Why the cam change? Same Grind right?



In terms of the fuel upgrade parts you talk about, what do you recommend as a fix and forget solution? Vulcan + Big Dog + F1?

 

[Fishin Guide]

Dave -

I enjoy reading about the work you have put into your truck. Thanks.

Why the cam change? Same Grind right?



In terms of the fuel upgrade parts you talk about, what do you recommend as a fix and forget solution? Vulcan + Big Dog + F1?

I assume you are talking about the second cam change. The first was from stock to the F1. This was solely to fix the lift pump solution. I was able to add a mechanical pump and I have not had one issue to date.



The second change to another F1 cam was actually a combination of reasons. Don M wanted to inspect the cam for any unusual wear and to just give it a good looking over. This would be from a real world truck that is driven and used daily. Not too many people have reason to send a cam back, so the opportunity to check it out was just too strong. The reason I was able to quickly swap the cam was that I popped the head gasket in the driveway. So, with all the parts out of the way, a cam swap was lightning fast. And the final reason is so that I could go to the new bolt on gear design. Just in case I ever decided that I did not have enough power or wanted to race or pull, ect. The press on gear was still fully seated and gave me no issues at all.



I don't know what the ultimate lift pump solution is. Even 12 vavles go through lift pumps. But you usually get in excess of 100K out of them. So, after burning up many electrics, the mechanical pump was the only solution for me. If I did not go this route, I would have used the RASP.



The F1 products have served me very well. Never overpromised or under-delivered. The new Vulcan Draw Straw was just another component I honestly originally had overlooked. I am firmly convinced that if I had done this as a first mod, before any power, turbos, trans, ect, ect, my original lift pumps would have had a better fighting chance. Would it have worked? I don't honestly know that it would have done the trick, but the logic for it's need is right in the results.



I mean look at the WOT pressure increases. That VP can only consume so much fuel at WOT no matter what I do. And I was pulling my pressure down to 22 psi at WOT and now I can't go below 37 psi. This is a simple example of what 1 mod did to reduce the restrictions on the suction side. I believe that an engine mounted pump, electric or mechanical, would benefit from -8 fittings and line on the feed side when coupled with the Draw Straw. If I were running a rear mounted pump, I would run -8 to the pump and -6 out from there.



The reason I don't see an issue with -6 on the pressure side is because pressure changes the rules. It's like porting a turbo charged engine. Why do companies use a vacuum bench in a pressure motor? It defies simple logic, but it goes on and you are told it's the best thing since sliced bread. Case in point, pressure drop from the outlet of my mechanical pump to the inlet of the VP is less that . 3psi. That's not a typo. When I was running a piece of -6 line to the inlet of my lift pump and an otherwise stock fuel system, I could bury a vacuum gauge. But I still had 45 psi at idle. Confusing stuff for sure. But with the new fuel setup, I cannot even get the vacuum gauge to budge. Even at WOT. So, I am at the limit of volume, spring pressure and fill volume of the lift pump now. Before I feel I was sucking air.



Sorry for the long reply. I think the ultimate fix is what you feel is the ultimate fix. This is what I think I had to do. And in hindsite, I really wished I had started here. Who knows how many problems I could have solved with just fixing the dang module!



Dave

 

[OPoole]

I have that one covered! :-laf



I even have a genuine OPoole hose kit from the pump forward. I was the one that got the custom machined pump nut and adapter. Ring any bells?



Since then, I have put in yet another F1 cam, changed to a little larger volume pump and upgraded the rest of the fuel system.



I should have a trick part for fuel regulation/ bypass in the next few weeks as well.



Dave

Yes it does! :-laf

 

[rweis]

With the Vulcan Draw Straw, has anyone come up with a tank low fuel pickup cannister?, sump system?



I am going to drop my tank soon and replace the plastic lines. I vent my return fuel back to the tank vent line now so that is not an issue.



How can I adapt the Draw Straw to pickup fuel at the lowest tank fuel level? Can I use the existing cannister but use the Draw Straw as the fuel pickup instead of the OEM pickup? What about the fuel gauge indicating system?



Bob Weis

 

[Fishin Guide]

With the Vulcan Draw Straw, has anyone come up with a tank low fuel pickup cannister?, sump system?



I am going to drop my tank soon and replace the plastic lines. I vent my return fuel back to the tank vent line now so that is not an issue.



How can I adapt the Draw Straw to pickup fuel at the lowest tank fuel level? Can I use the existing cannister but use the Draw Straw as the fuel pickup instead of the OEM pickup? What about the fuel gauge indicating system?



Bob Weis

Bob,



there's a few ways to do it.



You can leave the oem mesh on the bottom of the filter "puck" if you want to pull fuel from a well. This would be best for applications that see severe angles and are only mildly BOMBed. You would be pulling fuel from the same area the fuel returned to as well.



I gutted the stock module entirely. The draw straw runs through the bottom of the stock module and close to the bottom of the tank. Mine actually touches the bottom of the tank. I have used a slash cut in the tube to allow unimpeded fuel flow but to also get as close as possible to the tank bottom.



So far, absolutely no issues with pulling the fuel, even with the gauge on 'E'.



Now, the gauge is mounted to the lower slip section of the module. On my '02, We determined the depth and set the height with a few stainless screws. So, fuel level reads accurate and all works as it should.



A sump system could be made to work, but I am using the simplist system I could.



Dave

 

[DMannon]

I've been following this thread in light of what I've been going through with my truck: https://www.turbodieselregister.com/forums/showthread.php?t=165478



One of the problems I see with making the stock module ridgid, with screws or whatever, is the small amount of slide built into the stock unit is to allow for fluctuations of the tank, due to low/high pressure or hitting the tank on something (think rock or snowbank). I think that's what happened to my fuel pickup. It got dislodged from an impact and was floating in the cup. At low tank levels, I was sucking some air. Does the Draw Straw have any flexibility to allow for bumps?



From the Draw Straw instructions Eric emailed me: "Be careful not to run your tank too low after performing this modification. " His instructions set the DS in the bottom puck. Has anyone had any issues at low tank levels and on inclines? I have a STEEP driveway.

 

[Fishin Guide]

I don't think fixing the module length is a necessity. The only thing it relates to in the entire system is the fuel level sender. The lower portion of the module would most likely seek the bottom of the tank just from driving down the road anyway. This is the reason I gutted the factory filter mesh and reused the factory puck.



There is enough flexibility in the Draw Straw to allow for an impact or movement in the tank. On my buddies steep driveway, and I mean steep, he was still able to prime, start and run his truck with less than 2 gallons in the tank.



The Draw Straw allows for fuel to be pulled from the same height as the stock module. Unfortunately, if you install it the same way I did, you no longer have a well of fuel to pull from. I depend on the fuel level in the tank to be high enough to still have draw.



Dave

 

[ARoss]

Fixing the module shouldn't be an issue since the reason you are doing this is to scrap the clip on strainer. Once you determine the length of the module with the strainer attached, you simply remove the strainer from the base of the module and you should have a good 3/4"+ between the base of the module and the tank bottom. The Draw Straw is somewhat flexible, definitely flexible enough to take an impact from outside the tank.



I did the install this past weekend and left the outside screen on, but removed the inner one. I cut the pickup 3/8" short of the total depth of the tank to allow for the clip on strainer.

 

[DavidC]

I do not get this whole well thing on grades. That well only holds at the most 1/4 gallon. If your on a grade such as going up a 6% grade that 1/4 gallon is going to be gone pretty fast. If I remember right when I had mine out the pickup tube went into the bottom mesh and there was an upper mesh with a flapper valve on the bottom of the well that was spring loaded. It appeared that as the well filled the weight of the fuel would push down on the valve releasing fuel back into the tank thru the mesh. I did not see any correlation between the pickup and return. Can someone enlighten me if I am wrong?.



Dave

 

[ARoss]

Don't forget the return line dumps into the module and is maintained there until it is slowly fed back into the lower screen area for the pickup. When I pulled my module this past weekend it was full of fuel.

 

[rweis]

I route my return fuel back to the tank filler vent line to keep the hot return fuel out of the fuel pickup area. The entire tank then mixes with the hot return fuel to give a more even fuel temperature.



The second consideration when I rebuild the cannister is I am going to use the OEM fuel return fittings as a second fuel pickup line (will need to be modified as a fuel pickup obviously).



One fuel pickup dedicated to the RASP (or FASS or whatever you use). one fuel pickup dedicated to the OEM lp.



Bob Weis

 

[DMannon]

I took a picture of mine taken apart and put some crude labels on it.

#ad


Best I can figure, the fuel canister picks up fuel from inside the 'puck' which is normally 'underfuel'. The VP44 is constantly returning fuel into the cup, which by my figuring, holds about 2 quarts. If the fuel level is low, the cup drain valve is pushed open by the weight of the fuel in the cup and suction in the puck and fills the puck. The membranes (top membrane is missing in my pic) top and bottom keep enough of the cup fuel from washing away from the fuel pickup. Does that sound about right?



The Draw Straw seems like it would work best if it terminated inside the puck with a fairly good fitting hole through the bottom of the cup.



Kinda academic, though... I have a replacement pickup module coming from EBay.



Has anybody had good luck running 3/8 hose to the stock pickup fitting on module?

 

[Jeff Knight]

DMannon, The puck is what I cut all the screen out of. I put an in line filter from Vulcan before my Walbro. I got a dorman fitting from GDP and ran 3/8 hose to the top of the tank module. The valve is no longer in the puck. Jeff