Engine/Transmission (1998.5 - 2002) Modifying fuel system so temperature input to VP44, 80* - 100*, your inputs.

[rweis]

Filler Neck



I cut the T into the fuel vent line.

Procedure:

1. Take the filler / vent line out so you can work with it. DC has a rubber hose coupling at the tank end and 3 screws up at the sheetmetal end. There is also a gasket up at the sheet metal end.



2. I put in a T with 3/4 hose barbs on it and whatever way you are goign to connect the return line. Mine is AN-6 but yours could be something else.



The way I put in the T is:

1. Get your T all ready with the T and the hose barbs all assembled. I used a 3/4 T then put 3/4 hose barbs ineach end. Then get some 3/4 hose (I think I used 2@2" pieces) you are going to use as the cooupling on each end. 4 hose clamps of the right size.

2. Lay your assembled T right along side the vent line where you want it (I also run my RASP back to the vent line (therefore I have 2 T's in my vent line) so if you anticipate that, or think you might need a second T in the future then place your first T so you could if needed put in a second T later.

3. Mark the vent line so you give the T with the barb about 1/4" free space on each end. Cut the vent line. Clean the cuts so there are no rough edges or metal filings from the cut remaining.

4. Slide one of the 2" pieces of the 3/4" hose up onto the cut end of the vent line all the way onto the vent line. Don't forget to slide 2 hose clamps onto the rubber piece you just slid onto the vent line. Position the T in place and slide the rubber 2" piece down onto the hose barb that is one end of the T until you have aboutr 1/2 on the vent line and 1/2 on the hose barb. Put your hose clamps on and thghten them up snuggly.

5. THere is enough flex in the hose coupling that you can push the T out of the way so you can do the step #4 again for the other end.

6. Put the filler tube and vent line back in.



I like this arrangement because at cruise speed the VP44 (per Bk old thread) sends about 30 gph back to the tank. So you recirculate the whole tank every hour through your filtering system. And you mix the heated fuel with the entire tank for cooling purposes and keeping the tank fuel solution of fuel and additives throughly mixed.



Also the return on the VP44 has a little throttle bore in it to help relieve any air in the VP44 (ie it is in the highest verticle point of the VP44 and is designed to be there for this purpose (Bosch book pg 215 Overflow valve 3rd paragraph, Second sentence "Since the overflow valve is mounted on top of the pump housing, the throttle bore facilitates automatic venting of the fuel-injection pump. ")



What I found out about the return line.



1. You DO NOT want to restrict the line. I think I remember an absolute limit of 10 psi restriction or the VP44 will not be able to get return fuel into the return line. You know about how high on the engine the T is. The tank vent line in not more than about 12" higher and if you have NO restrictions in it you should not create any psi difference.



2. I took my return line off where it comes out fo the T going back to the tank. I was amazed that the large black covering down by the frame that the return line is encased in is about 3/4 inch, BUT THE ACTUAL RETURN LINE IS ONLY ABOUT 1/8" ID, 3/16" AT THE MOST. The actual return line is a nylon / teflon type material that is inside the 3/4" large black sheath and sweges INSIDE the 1/4" steel return line where it mates down by the frame.



I feel by opening up the return line to 3/8" ID it should flow better IF there was any restriction in the stock configuration. I just do not see where 30 gph can flow easily through a 1/8" ID hose. Maybe one of the engineering types or someone more knowledgeable than I am in fluid dynamics can help out here in the concept of "can a 1/8" ID hose flow 30 gph and if so at what psi".



I have not had any pressure build up in the tank. You are not changing anything but where the return line returns back to the tank.



Timer



I used a automotive relay to take the load off the timer board relay contacts. I thought if I could get the 10 amp relay on the timer board down to milliamps and use the heavy duty easily replaceable 20 amp relay of the amperage, the timer board relay should last forever. I just use the timer board to trigger coil voltage to the automotive relay and let the automotive relay do the current switching. My blower is like yours, only about 3 - 5 amps. Either way. I like to do it once and be done with it for a very long time not to be revisited. Whichever way.



If you have any problems or questions can call my cell phone 863. 206. 3464.



Bob Weis



P. S. Gary - I think I can pull the 5er this week for a couple of hours on thursday to test the heat / load concept.

 

[JAG1]

Thanks Bob. While doing this return line mod I did notice what you are saying about the line coming down off the T. Looks like cheapo cracking type plastic fuel line under the sheath. Why they ever did this ..... who knows. I have enough line (bought too much) to change it to the high temp rubber diesel line. I'll do this when I insulate the return line near the block.



I completed my next step of fuel system. I added a screened tank vent up to the fuel door cabinet. Just inside on the left. This gets rid of the clogging rollover safety valve problem without just drilling it out and maybe getting water in there. This allowed me to use what was the fill neck vent for the fuel return line. I just cut the vent tube off and left a long enough stub to connect the return hose to the side of the fill neck. It's interesting to look in there now and see a fair amount of steady fuel flow at just idle. Works great! helps to mix additives too.

 

[Gary - K7GLD]

I used the tank fill/vent line for the fuel transfer feed from my in-bed fuel tank - that is pumped by a Carter pump similar to the LP and pusher pump. I made sort of a "Y" connector out of copper, used the same setup on the '91 truck, and now this one, absolutely no problems with either truck:



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[JAG1]

Would you guys tell me what rating of potentiometer you bought for your blowers. I'm going crazy with electronic supply houses sending me on a wild goose chases. Getting conflicting info (amazing how supposed experts tell you all sorts of things), bad directions to places that don't exist that sort of thing. Where did you buy yours and how do I know if its the right one. Thank you, Mike.

 

[rweis]

Well, it is a tad bit more to it than just a potentiometer.



The key to controlling a DC motor is PWM (Pulse Width Modulation). What this really means is instead of sending a steady stream of 12v to the motor, you send lttle packages of 12 volts to the motor. You can vary the length of the packages, but each package is fully 12 volts. If you do not use PWM you burn out the motor because you give it only 9 volts, or 3 volts or x volts when it is designed to run on 12 volts.



How do you get the PWM packages in reality? You use a PWM logic board that develops full 12 volt packages and has the potentiometer on it (in the circuit) that you use to vary the motor speed. Yes it is another seperate circuit board.



However you may have mine if you want. WHY?



I found that to get the blower motor running noise (after engine shutdown) down to something quiet that the purpose of the blower was essentially nullified. The blower motor was running so slowly that it was not pushing much air (maybe 50% of full wide open). Instead of that I run mine directly connected to the battery (through a fuse / relay of course). Is it noisy?, YEP IT IS. Does it push air?, YEP IT DOES. I just did not want to have the further complication of the PWM board. I think Gary does use the PWM board, and likes it.



Let me know if you want mine, or want to try it. I'll gladly send it to you (I have it mounted in a nice little black pheonelic box). You may like it, who knows. I just wanted the full motor speed for full CFM.



Bob Weis



When you get your timer circuit, go back and read HOW Gary modifies the wiring to get the timer board to power the blower after you shut off the ignition trigger circuit. Pretty neat idea Gary came up with.



One of these days I am going to learn how to post pictures on TDR and will fully document what this whole setup looks like.

 

[Gary - K7GLD]

I posted this pic earlier in this thread, but will do it again to eliminate the need to page back thru - here's a pic of the 2 separate electronics boards I use to adjust the turnoff time of the added blower - that one is seen to the right in the pic below, and the other to the left is the Pulse Width Modulator used to adjust blower speed to lower voltages and speed without damaging the blower motor. I'm running mine at just under 5 volts (just under 2 amps) to obtain adequate airflow combined with acceptable VP-44 temps - and have the timer set to allow the blower to run for about an hour after the engine is shut down:



#ad


These both are secured with Velcro to the top cover of the driver side fuse/relay box on the fender well:



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[rweis]

Empty run & Towing run compleated



Conditions #1

Empty

Fuel level last 1/8th before low fuel light so there is essentially no fuel mass

OAT 55*

No OEM ff (ie under the hood heat sink)

VP44 input llines are thermally wrapped to avoid absorbing under hood heat

VP44 output lines are thermally wrapped to avoid absorbing engine block heat

4 fuel coolers (2 frame rail coolers, 1 cylinder transmisson cooler, 1 H7B radiator type transmission cooler with 1000 cfm fan) all on return line.



Conditions #2

Towing 13. 5k tall fiver

Full fuel tank, took 1 hour of cruise until input fuel temp stabilized, ie tank is up to stable temperature

OAT 54*-55*



VP44 OAT 240 CFM Blower

Fuel returned to tank vent line

Drive time 1 hour (30 minutes at each rpm on interstate or non stopping road to maintain that rpm consistently (no lights etc))



#1 empty

OAT 55*

RPM 2000 63 mph

VP44 EBC 65*(OAT +10)

input fuel temp 70*(OAT +15)

output fuel temp 85*(OAT+30)



#2 towing

OAT 54

Rpm 2000 63 mph

VP44 EBC 67*(OAT+13)

input fuel temp 74*(OAT+20)

output fuel temp 93*(OAT+39)



#1 empty

OAT 55*

RPM 2500 55 mph (O/D out) I could not go 2500 rpm O/D in and still be legal

VP44 EBC 65*(OAT+10)

input fuel temp 75*(OAT+20)

output fuel temp 95*(OAT+40)



#2 towing

OAT 55*

RPM 2500 55 MPH (O/D out) same reason

VP44 EBC 70*(OAT+15)

input fuel temp 77*(OAT+22)

output fuel temp 100*(OAT+45)



_____________________________

Gary is right



there is more VP44 temperature and increase of fuel output temperature when towing at the same rpms and conditions as empty



I thought it would be the same

_____________________________





Thoughts:

The VP44 blower helps cool the VP44 and indirectly the fuel input at cruise speed. I think the larger the difference between OAT & fuel temps the more effective the blower becomes a fuel cooler by keeping the VP44 body cooler.



VP44 output temp is a direct relationship of RPM. AND Apparently load towed.



Trying to exprapolate the results:



On a hot summer day the OAT is 45* hotter than test temp. If the temperatures relationships hold true that would:



Empty

2000 rpm summer input fuel at 115* output fuel at 130*

2500 rpm summer input fuel at 120* output fuel at 140*



Towing

2000 rpm summer input fuel at 119* output fuel at 138*

2500 rpm summer input fuel at 122* output fuel at 145*



and that is with the VP44 OAT blower

4 fuel coolers

the return line is returned to the tank vent line



Remember the maximum fuel input temperature is 160*. This still leads me to believe there is a inherent fuel input temperature problem with the stock fuel setup at cruise speeds without VP44 cooling and fuel cooling.



If I get a chance I'll rig up a bypass to the fuel coolers so the stock truck guys can see a better picture of what I think is a problem.



I think I have the problem solved for my truck and my conditions. I think that each of us has to determine what their conditions are and modify the fuel system as needed.



Bob Weis

 

[JAG1]

Those are nice pics Gary... . you do nice work.



Bob, I don't know what to do, I'm concerned about adding something looking too complex for the dealer, other than a simple dash switch, that may affect my warranty. I Have a ways to go before a hundred K miles. What do you think?



Nice of you to offer the PMW and cover. Can it be adjusted for a higher blower speed? For times getting home and noise doesn't matter?



If I decide to go the whole setup like you or Gary, I'd like to ask Gary if maybe he could set me up electronically if I drove out to Eastern Oregon. I have a truck camper, and would like some help, would like to pass along some money too if you would let me, I'd appreciate it. I went crazy trying to deal with electronic supply houses..... ended up a bad day after that.



All I have is the blower and duct installed with the blower wiring hooked up, with fuse but, coiled up to the firewall ready for some switching like you guys.



Thank you Bob and Gary.

 

[Gary - K7GLD]

Gary is right



there is more VP44 temperature and increase of fuel output temperature when towing at the same rpms and conditions as empty



I thought it would be the same

AH, sweet vindication! :-laf :-laf



I was pretty sure my eyesight and theory were correct from my own RV towing runs - and in my case, we had what was probably a heavier VP-44 load - and more heat buildup - due to towing in steep mountain grades you don't have out there in Florida.



Jag1, Let me give that some thought - once fair weather hits here, we spend lots of time out RVing, so working out a schedule might be an issue. It requires a bit of time to order and receive the kits, then get them assembled - and probably the better part of a day to get it all assembled on the truck - but, I can work out a parts list, and if you're interested, PM me and we'll see what we can sort out.

 

[rweis]

So Gary,



With your mtns and heat index howmuch hotter was your Vp44 readings?



I want to ballpark what the temp going back to the tank is and the difference from input fuel temps. Right now I woulod tell someone that fuel back to the tank is OAT +40* then it depends on fuel cooling as far as what is then fed to the VP44, in my case OAT +20* but I have mods as discussed previously.



I just can not imagine what the unmodified truck sees. "And THIS is what DC calls automotive engineering?"



Bob Weis

 

[JAG1]

Not to worry Gary/ Bob. I've decided to keep it simple and just put in a dash switch. I know it's not like you guys but, I gotta' watch too:-laf :-laf .





Btw, I really enjoy reading your stuff on this thread. Thanks, Mike

 

[Gary - K7GLD]

So Gary,



With your mtns and heat index howmuch hotter was your Vp44 readings?



I want to ballpark what the temp going back to the tank is and the difference from input fuel temps. Right now I woulod tell someone that fuel back to the tank is OAT +40* then it depends on fuel cooling as far as what is then fed to the VP44, in my case OAT +20* but I have mods as discussed previously.



I just can not imagine what the unmodified truck sees. "And THIS is what DC calls automotive engineering?"



Bob Weis

I'd be hard pressed to come up with specific numbers, lots of other monitoring going on at the time and it's been a while, but a rough guess would be about 15-20 degrees added return fuel line flow temp rise on long steep grades when towing, with a smaller, but corresponding rise at the PSG as well - perhaps between 5 and 10 degrees - I'll do more testing when we next take the RV out in a month or so - mountain runs are no problem, we're completely surrounded by them... :-laf

 

[rweis]

Old thread, but I'm still playing around with how to keep the fuel cool as passively as possible.



During this part I have the VP44 return plumbed into the tank vent line.



I have installed a aux bed tank. I put a shutoff valve between the aux tank and the gravity feed to the OEM. First I tried the Notherern Tool aux tank valve only to find there is a severe restriction in the Northern Tool valve that cuts the gravity feed to a slow drip. Then I plumbed the aux tank feed into the fuel vent line for awhile. Second I find the 1/8" opening in the fuel shutoff valve I had between the aux tank to the OEM tank will not let sufficient fuel to pass to have the aux tank refuel the OEM tank while driving at any speed. Then I get a fuel rated 3/8" ball valve from West Marine. A huge passage through the valve.



At this point I wanted to try returning the VP44 return fuel to the aux tank for fuel cooling while feeding the aux tank to the OEM by gravity 3/8" plumbed into the tank vent line.



Route of the fuel is DrawStraw pickup, RACOR 690T (90 gph) filter, RASP, VP44, fuel bypass back to the OEM tank vent line for excess fuel from the RASP, the VP44 body bypass valve routed back to the aux tank through 4 frame fuel coolers, aux tank gravity feed the OEM tank fuel vent line.



From a short test run tonight I think I am finding that gravity feed (3/8") can not keep up with the VP44 body bypass return fuel flow when the rpm's get much over 1500 rpm. I'll test it more the next week or so, but I am thinking that a 2nd aux tank feed to the OEM tank is needed to cover the amount of fuel the VP44 is returning to the aux tank as well as drain the aux tank.



At cruise speed (2000 rpm?) the Vp44 returns 31. 5 gph back to the tank. I do not think the aux to OEM gravity 3/8" drain is handling this amount of volume. Next week should tell, more later.



I do not want to pump the aux tank into the OEM just to keep the complexity down.



Bob Weis

 

[rweis]

Confirmed:



Gravity flow in a 3/8 AN-6 can not keep up with the VP44 return fuel to the tank.



After 2 more days of test, every time I drove for any distance (10 miles + at 2000 rpm) the aux tank started filling up. Not real fast, but definitely filling up. I drive about 17 1/2 miles to work.



I also had an aux tank vent line in the same plumbing line that the VP44 was dumping into the aux tank but about 3 inches vertically above it. There is enough volume comming back the VP44 return line that a good bit of fuel splashed up 3 verticle inches and out the vent line instead of falling vertically down the vent line into the aux tank.



What this tells me is at cruise speed (2000 rpm) you need to allow for a significant amount of fuel (up to 31. 5 gph) to come down the VP44 bypass valve that is mounted into the VP44 body. I find this interesting because the OEM plumbing going into the engine T for the VP44 return line and the injector return line is not very big ID plumbing (3/16" maybe). I think this means there must be much higher psi at the engine T than I orgionally thought (maybe 10 psi + ?).



Anyway this is an FYI as to what I observed.



I replumbed the VP44 return line back into the tank vent line where it had been working well. Just trying a different idea that did not pan out, oh well.



Bob Weis

 

[Gary - K7GLD]

Just a short followup as to running, longer term over-the-road experimenting and verification of usage, from my own setup at least, as described in this lengthy thread.



To date and after about 10K miles with lots of varied driving situations, from local grocery runs to hundreds of miles of mountain towing with our 5th wheel, my setup has operated flawlessly - measured temperatures at the VP-44 in the PSG area are consistently FAR lower and more stable than prior to the installation of the cooling setup - the timer has been set to run for about an hour after engine shutdown, totally eliminating the effects of underhood heat soak from both the VP-44, as well as the nearby APPS, which is also a heat sensitive device.



Total cost for my own setup is less than $100, and $$$ well spent as far as I'm concerned.



Much thanks are due to Bob for originating this thread, as well as being one of the most active contributors towards a final solution. Many other helpful contributors are also due sincere thanks for their input that kept the rest of us moving forward, and often provided support and vindication of what we were trying to accomplish.



MISSION ACCOMPLISHED - and many thanks guys! Oo. Oo.

 

[Curious Dave]

My Eyes !!!! Ouch !!!

okay guys... . That was simply awesome data! My eyes now hurt from all of the 635 posts read in a few days. :{

Anyway... I have the FASS system plumbed/returned from/to the bottom of the fuel tank. with braided #8 line all the way to the stock ff. I then have some special made AN fittings that accept #8 to the stock threads. This was done to eliminate the banjos. I then ran #8 to an AN "manifold" with #6 to the VP. I also have a "T" in the middle of the manifold that is used for 2 purposes:

1. To hook up a mechanical fuel pressure gauge.

2. To "burp" the system back to the fuel fill spout. The "burp" is controlled by an AN ball valve. This is now used as a regulator to control back pressure on the line to keep consistent pressure to the VP. With a potential burping as the system sees fit to do on its own.

The reason for the "burp" is because I have an annoying chatter on my guage that won't go away unless I burp the line. #@$%! I was hoping to eliminate the line cracking needed to calm the gauge down, but no such luck. I have gotten tired of trying to figure out how the air keeps getting into the line. I then found this post and after a few days. . Now I too have bleeding eyes. :{

Anyway! I am seriously looking at doing the cooler with bypass in front of the radiator (for seasonal adjustability) as well as maybe a (bypassable) cooler in the "burp" line. Thoughts on this cooler would be to cool the fuel more on a contiunal (seasonal) basis instead of just going to the engine or away from it.

I am also giving thought to the "Breadpan / Clothes Drier Ducting" thing. I am not much of one for understanding the whole electronics gig Bob and Gary did. But I have found various 12v dc timers. 8 event programmable too! (I am looking around at all of my gizmos to see what else I might want to control with a timer). My whole reasoning for the cooler fuel is to get rid of this dancing gauge. After reading this "rope" I realized there was some potential confirmation of a thought I had. That would be... that the fuel might be getting hot enough to get air in it in the lines and that is why I keep having to "burp" the line. Almost like a vapor lock in gas setups.

Anyway, I am wondering if you 2 guys, or anyone else, might know how or where I can find a temp. activated device to connect to the timer to control a fan like the one you guys put in your duct work. I am lazy and don't want to have to remember to turn it on or hook it into the truck wiring. I am also looking at doing the solar panel to battery, via a regulator, thing. Please let me know what you guys think.

Oh Yeah! Bob... I have an aftermarket hood with a Viper style scoop in it. I liked your idea about the hood scoop thing and I am planning on looking into that aspect. I don't see how it would work reliably with a blower (no where to mount the blower and still be able to open/close the hood), but the ram air idea might work. I was thinking of doing it originally for the air filter, but I see more potential benefit for the VP.

 

[rweis]

I have been doing the fuel cooling for about 2 years (maybe 3) this summer. I monitor the fuel input temp like most monitor the boost or EGT. Some observations:



Running empty (meaning moving forward so I get air flow over the inline coolers) (with 4 inline fuel coolers) and returning the fuel to the filler vent line, the fuel is OAT + 10 - 15. Towing 13k 5er the fuel is OAT +20 - 25 (10 degrees hotter, way back in the thread Gary suggested the VP44 temp had something to do with load. I thought how could it, how would it know? It does! It also has to do with rpm. ).



The hottest OAT I have experienced is 105. Towing, input fuel was 130. Bosch max is 160. Without the fuel coolers I have NO doubt the fuel input temp would have been WELL over the limit.



How you cool and where you place your coolers does not matter. However, I have about 140" of cooling fins. I never could get ALL the heat generated by the VP44 out. The best I could do is get all but 10* out (VP44 generates 40*, I get 30* out). The tank does little in temp removal except for fuel volume (ie full tank the temp rise is slower, low tank the fuel rise is faster).



Air in the fuel.



I do notice the hotter the fuel the more air is in it. However, I pump about 2x what the VP44 needs and bypass the rest. My bypass fuel has most of the air in it. The VP44 fuel has little air in it and I think the VP44 return bypass takes care of the little air it does get.



You just have to find a way to get the fuel cool, as the stock system really sucks in that department (and in every other department as well).



Good luck with coolers in front of or where ever. I find flowing air is really all you need. You can see the fuel temps rise if you are stuck in traffic and not moving. I would install a fair amount of footage of cooling line unless you find a better way than moving outside air to cool the fuel.



I never persued the hood vents to get engine compartment heat out. Might work well.



Bob Weis

 

[monkeyman]

I installed a Flex-Lite fuel cooler in line from Fass before VP44. Put it right next to intercooler. Plan to add small fan also and By-pass for winter. I am going to install a inline check valve as extra line causes about 60 seconds of low fuel pressure. I did notice in 88 degree weather a 25 degree drop in fuel temp.
Rick

 

[PRout]

This is one of my planned mods to come also. The only thing is I'll probably add the fuel cooler, plus maybe just a long length of simple bendable copper tubing bent up like a pretzel in front of the existing radiators, or maybe along the frame with rubber "rub through protectors" in between. It will go into the "Return" line that goes back to the tank because again as Bob suggested before, that is where the biggest fuel differential will be and will provide the most cooling. Plus, you don't interfere with fuel flow to the VP44.

Monkeyman, sure is on the right track as 25 degrees is big stuff when that is a major source of cooling. Like they say, heat is a major factor in the life of mechanical parts.

 

[rweis]

I installed a Flex-Lite fuel cooler in line from Fass before VP44. Put it right next to intercooler. Plan to add small fan also and By-pass for winter. I am going to install a inline check valve as extra line causes about 60 seconds of low fuel pressure. I did notice in 88 degree weather a 25 degree drop in fuel temp.

Rick

The 25* drop, from what to what?



Bob Weis