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

[keimmmo]

I relocated my fuel return today. I actually did it more to help mix the used oil I pour into the fuel than to help cool the fuel. Wasn't hard at all.



I decided that the fill tube dumps into the tank farther away from the fuel pickup than the vent line. So, I drilled a hole in the fill pipe and brazed in a 3/8 fitting. I cut the return line just ahead of the fuel tank. The pressure line to the motor is 3/8. The return line is 5/16! I made a "Y" fitting with a 5/16 inlet and outlet and a 3/8 line to go to the new return. I brazed the outlet shut going to the original return and drilled a . 040 hole in it. It is neater and stronger than just plugging the original hose. It will still drip a little fuel into the original location, but it will be so little that it will not be significant. Maybe the slow movement and extra line under the truck will act as an additional cooler...



Steve Keim

 

[BDanner]

Vp44

Before I read these 17 pages I Googled for fuel cooler suppliers. In reviewing fuel coolers I discovered that the European diesel market is way ahead of us in turbo diesel technology. I am not implying that this is the definitive ideal location for a cooler, but I would bet that a lot of German research went into deciding where to locate the cooler on this new Audi A6 http://www.hydro.com/en/press_room/news/archive/2004_03/audi_a6_geneva_en.html . Midway down is the fuel delivery and fuel cooler.





My latest dillema in upgrading has been the hard start syndrome suffered by many of us after a FASS install. It occurs after driving and shutting down and restarting while hot. It takes 2-3 seconds of cranking inorder to restart I let my wife go to NY from VA with a horse trailer this weekend and showed her how to crack the injectors if she gets a serious vapor lock.



WHAT NEXT!!



Most of the threads will say your VP44 is going and needs replaced or add a fuel pressure regulator. I have not read that any of these fixes cure the problem. It is strange how this suddenly occurs after this upgrade. I contacted Performance Diesel where it was purchased and discussed my installation, symptoms and perhaps the issue of high pressure.



My guage reads 18-20psi at idle and 15-17psi at FT. They told me that the VP44 computer is reacting and dying due to the latent high underhood temp and that a vapor lock occurs due to the heat of the fuel. They responded that they only see starting problems on VP44s that recieve over 25psi.



ANSWERS TO PROBLEM FROM PDS:

1. Add a fuel cooler to frame rail on return side like the Duramax.

2. Add fuel supplements to lower fuel temp and add lubrication to pump.

3. Lift hood if hot and cool if location permits.

4. New VP44 replacement



I realize this thread is geared toward cooling the VP44 and increasing it's life, but any help or ideas with the FASS problem and high temperature would be appreciated, especially ideas excluding VP44 replacement! :{

 

[BDanner]

Vp44 + Heat

Before I read these 17 pages I Googled for fuel cooler suppliers. In reviewing fuel coolers I discovered that the European diesel market is way ahead of us in turbo diesel technology. I am not implying that this is the definitive ideal location for a cooler, but I would bet that a lot of German research went into deciding where to locate the cooler on this new Audi A6 http://www.hydro.com/en/press_room/news/archive/2004_03/audi_a6_geneva_en.html . Midway down is the fuel delivery and fuel cooler.





My latest dillema in upgrading has been the hard start syndrome suffered by many of us after a FASS install. It occurs after driving and shutting down and restarting while hot. It takes 2-3 seconds of cranking inorder to restart I let my wife go to NY from VA with a horse trailer this weekend and showed her how to crack the injectors if she gets a serious vapor lock.



WHAT NEXT!!



Most of the threads will say your VP44 is going and needs replaced or add a fuel pressure regulator. I have not read that any of these fixes cure the problem. It is strange how this suddenly occurs after this upgrade. I contacted Performance Diesel where it was purchased and discussed my installation, symptoms and perhaps the issue of high pressure.



My guage reads 18-20psi at idle and 15-17psi at FT. They told me that the VP44 computer is reacting and dying due to the latent high underhood temp and that a vapor lock occurs due to the heat of the fuel. They responded that they only see starting problems on VP44s that recieve over 25psi.



ANSWERS TO PROBLEM FROM PDS:

1. Add a fuel cooler to frame rail on return side like the Duramax.

2. Add fuel supplements to lower fuel temp and add lubrication to pump.

3. Lift hood if hot and cool if location permits.

4. New VP44 replacement



I realize this thread is geared toward cooling the VP44 and increasing it's life, but any help or ideas with the FASS problem and high temperature would be appreciated, especially ideas excluding VP44 replacement! :{

 

[keimmmo]

DBanner,



I posted on the thread YOU started. I suspect your problem is more related to too much pressure at start up. I had the problem a couple of years ago when running a pusher pump.



The factory location of the fuel filter adds a huge amount of heat to the fuel. The first step I would recommend in lowering your fuel temp would be relocating the factory filter like I did. Getting rid of a major source of heat is as good as or better than adding a cooler!!!



Steve Keim

 

[Mundgyver]

Well I finally got to check my mileage this week. I towed a car hauler 45 miles and managed to check the temp of the VP with my hand. It was cold to the touch and the fuel cooler that I installed which is a NAPA Rapid Cool model 1-7511 was warm at the bottom and cool at the top. So I am happy about the temp issue. No more worries there.



Today I did my run down South to Eugene, Oregon. I picked up exactly a . 1 mpg gain. Not earth shattering and maybe not worth the price of the cooler, but it was a gain. I feel real comfortable now and am not worried about the VP. I have 150,000+ miles on it now and it is the original.



I think placing the cooler before the VP is all I need. I'm not going to worry about the return line.



Almost forgot, moved from a 23. 9 to 24 mpg with this mod.

 

[rweis]

Got the fuel temp sensor installed just before the VP.



Very early indications are the ff is the culprit for hot fuel in my system (I have moved the return line back to the tank filler and have a H7B & fan there).



1 test drive, 8 miles, starting OAT 75*, before engine start fuel sensor temp 75* (first engine run of the day), tank 1/2 full and also 75*. Fuel temp climbed to 90* after about 8 miles as the engine compartment started to warm up.



Opened the hood slightly during 1hr+15min stop. OAT on return 78*, fuel sensor temp prior to engine start 78* (second engine run of the day), tank 1/2 full and 76*. Fuel temp quickly went to 80* and then started climbing to 100* on the 8 mile drive home as the engine compartment began to reheat.



Home, fuel coming right out at the tank feed line 77*, fuel temp into the VP 100*. There is nothing between the tank feed line and the temp sensor except the RACOR 690 ff, RASP, plumbing, ff.



I am going to run this for a week, then I am going to bypass the OEM ff (I have a RACOR 690 to remove free water and particles) and run that to see what happens.



Bob Weis

 

[Texas Diesel]

ANSWERS TO PROBLEM FROM PDS:

1. Add a fuel cooler to frame rail on return side like the Duramax.

2. Add fuel supplements to lower fuel temp and add lubrication to pump.

3. Lift hood if hot and cool if location permits.

4. New VP44 replacement

Geee, 1,2, & 3 sound like what I have been saying.

 

[R-N-R]

I used heavy duty industrial strength chemical/welding resistant ergonomic floor mat to insulate vibration noise from the frame mounted pusher. I am thinking about trying a piece of this between the filter and the block. Any thoughts or comments on this idea?

 

[keimmmo]

When I first mounted the pusher, the noise about drove me nuts... maybe nuttier. I made long mounting studs out of all thread, drilled the holes extra large in the bracket mounting the pump to the frame, and mounted the pump with rubber above and below the bracket. I double nutted the studs so the nuts will not work lose. The rubber was a piece of sidewall from a junk tire. Almost eliminated the in cab noise from the pump.



Steve

 

[rweis]

Well, rather than relocate the OEM ff I am going to bypass it with an inline ff.



I have a RACOR 690 back at the tank as the first thing in the fuel system to get particulates and free water out. Also use Stanadyne PF to help with that and lubricity. With just a couple of 3 runs with the fuel temp sensor running it is quite obvious that about 10* - 15* of fuel heat (on short 17 mile empty runs to work) is being picked up at the OEM ff. The first run of the day when everything is cool from overnight temperatures, the VP input fuel temp stays equal to the tank temp until the engine warms up and the OEM ff starts absorbing under hood heat. Then the VP input fuel is 10* - 15* hotter than the tank with the OEM ff as the only place tht kind of heat could have been picked up.



Even on shutdown, idleing or even a fast idleing with the hood closed do nothing to get rid of the fuel heat because the OEM ff is sitting there absorbing the under hood heat.



I did a fast idleing with the hood totally up and as the under hood heat started to disipate with the totally open hood the VP input fuel temp started to drop.



However, Even with the RACOR as the first element of the fuel system I just can not keep from puting a second filter before the VP just in case something should break loose somewhere in the fuel system and possibly screw up the VP ($$$$$). I went looking for a easy relocatable ff with at least 10um filtering and really good flow.



I found an inline ff at http://www.racerpartswholesale.com/canton2.htm that is designed to filter diesel @ 8um and I asked about the flow rate and "Per Canton, the flow rate on CA25915 is 90 gallons per minute" which should handle our 45 gallons per HOUR requirement easily. I ordered one and it is on the way. Notice the input / output is AN-12. Well Aeroquip makes an AN-6 male to AN-12 female reducer (Summit ~ $8) that will get that AN-12 of the Canton to my regular AN-6 fuel lines (the reducers are on 4 weeks inventory backorder).



I plan to run the Canton inline ff spring, summer, fall and then do a simple short hose swap to run the OEM ff in the winter (maybe here in FL I may not even swap the OEM ff back in during the winter).



So it will take a month to get definitive answers on VP input temps without the OEM ff and still protect the VP. But I am certain that the OEM ff is the VP input fuel heater. Probably designed to be so to keep fuel from gelling, but drives up the VP internal temps I think about 20* - 50* above OAT during all day long hard pulling (ie hotter under hood temps). I also think with the return (or pre VP) cooler with a fan you might be able to cool the tank below OAT given a long enough engine run time period probably in hours.



If you could pull heavy in the summer and cool the VP with 80* fuel when the OAT is 100*+ and the under hood temps are 110*+ (Gary said the under hood temps are about 10* hotter than OAT) then maybe the heat soak of the VP after shutdown can be contained to under say about 120* which should keep the VP electronics well within operating limits and keep the solder on the VP electronics board from crystalizing and the VP failing.



This will take a little time for the Canton inline ff parts to arrive and I will collect data and post it from time to time, but I think we are really close to being able to control the VP electronics heating issues.



Bob Weis

 

[Lsfarm]

In the meantime

Hi Bob, while you are waiting for the fittings, you could try to insulate the factory FFilter with an isolation shim under the mounting bolts, just a piece of 1/8" or less plastic or nylon. And then wrap the FFilter housing with a layer of 1/2" foam like carpet padding.



Doing the two above items should reduce some if not most of the under hood heat that the FFilter is currently absorbing.



I found that most metal items under the hood were in the 130-145* range from the hot air coming through the radiator. The metal fan blades themselves were around 145*.



If just insulating the FFilter works some it may be a simple and quick way for truck owner who is a lot less inovative and inspired than you are to reduce the fuel temps to the VP. I'm going to give it a try. But with your data bank of temp readings, if you try insulation it will net the most accurate information on how effective the insulation actually is.



Thanks again for all the work you've done on this subject.



Greg L

 

[rweis]

Sure, I can do that.



I have a PVC blank cover off an outside electrical box that should work for the mounting isolation, and just regular carpet foam 1/2"? (I'll just zip tie it around the ff, ok?).



Driving to work I watch the VP input fuel temps and it is so obvious. First couple of miles before the under hood heat builds there is hardly any movement from OAT. Then as the radiator temp gets off the bottom peg and indicates the engine is warming up the VP input fuel temp starts up.



I am at about 1/4 tank to take data to see how low fuel tank volume effects the whole thing.



I'll do the wrap first since that is the easiest to mod and try that for a couple of days, then put the shim in and watch that combination for a couple of days.



We WILL get this VP thing figuered out! Good input, good testing, yields good results.



Bob Weis

 

[jjohn]

Sure, I can do that.

Bob Weis

Thanks Bob,

I was wondering if insulating direct metal to metal block heat would make a difference also.

 

[Lsfarm]

Temp readings

When I take temp readings of the engine and accessories almost everything reads around 130-145* except for the radiator hose and fittings. Even the brake master cylinder is around 130*



This is when on the road and the radiator has been 'working' Even the intake side of the cylinder head reads about the same so I'm sure that there is some heating by conduction of heat, but I'm leaning towards a lot of heating by the hot air from the radiator and other coolers up front.



I have some 1/2" soundstop foam that has a reflective mylar surface, I'm going to try a piece of this foam, thinking that the reflective surface facing out will help reflect some heat away.



And no, I'm not trying to make my fuel filter quieter!! Just cooler :-laf



Looking forward to your results Bob.



Thanks for the work, Greg L

 

[keimmmo]

I'm CERTAIN that the filter housing is soaking heat from the block... both through direct contact and by just being close to the hot head. My relocated filter is just barely warm after a couple of hours of driving... not hot at all. I would definitely want my bath water warmer that the filter housing! I can COMFORTABLY hold my hand on it, where it used to be too hot to keep my hand on. MAJOR DIFFERENCE! And, it is still under the hood!



The inlet side of my fuel cooler is about the same temp as the FF. The outlet is near ambient temp.



I live in a warm climate most of the year, so the fuel heater in the factory FF usually is not an issue. However, I have been in Illinois a few times when it got pretty cold. I want something that will help keep the fuel from gelling if I see cold weather without having to re-enginier the fuel system! (If it gets that cold I will also cover the cooler with cardboard... I will want to block the radiator some anyway since I run a 180* thermostat. ) I will not say that I have the ultimate fuel system, but I think it is very good and should be practicle for both warm and cold weather.



Bob, as another test, PLEASE hang the FF from a piece of wire so it is not touching the motor at all and get some readings that way too. Try it both with and without insulation... if for no other reason than to give me an idea of MY fuel temp.



Bob, and others, thank you for your work! I'm sure we are on the right track to both improving VP life and even helping the fuel economy as well.



Steve Keim

 

[rweis]

Ok, I'll hang the OEM ff first for a couple of days, I LOVE tie wraps and get some readings to verify temps for Steve.



Then I'll remount it with a PVC insulator between the ff and the intake manifold.



Then I'll wrap it (I also have some old windshield sun blocker reflective foil that you put in the windshield to keep the inside of the truck cooler) in this and get some readings and then the foam and get some readings.



Ultimately though I am going to have a 2 options in the fuel delivery: 1. inline ff on the frame, 2. OEM ff in orgional position. Then based on what the temps are (spring, summer, fall, winter) and anticipated truck load (empty, towing the RV) and terrain (mountains, flat land) switch it. My goal is fuel temps of minimum 50* - maximum 80* into the VP. I'm thinking of plumbing both right to the fuel temp T and caping the one I do not want to use. Simple female hose end cap, 5 minute job.



Fuel gelling I use Stanadyne PF, depresses pour point like 60*.



Bob Weis

 

[rweis]

Steve,



I took the OEM ff off tonight and zip tied it to the master cylinder to hold it over that way away from the block. It moved it toward the fender about 6" and on a 45* tilt from the block to the upper fender. I had to unplug the smaller of the two electrical connectors as it was not long enough. Will take temps tommorrow.



Bob Weis

 

[rweis]

Temps for Steve,

Configuration, OEM ff taken off and zip tied to master brake cylinder housing.

Truck was not carrying any load

This was traveling to an adjacent city. Some mph as high as 50mph for 10 minutes at a time. Many stop lights. Some residential street type driving.



Non standard permanent modifications

VP/Injector return fuel runs through an H7B cooler with a 1000 cfm fan and then plumbed into the fuel tank vent line. The H7B typically drops the VP return fuel temp by about 10*. RASP lp.



To work I drove 17 miles, OAT 77*, 1/4 tank, VP44ift 77* - 87*, OEM ff body at end 93*, VP electronic bay at end 103*.



From work I drove 80 miles in 93* OAT with 1/2 tank and the maximum VP44ift (VP44 i(nput) f(uel) t(emp)) was 112*. The rise to 112* was slow and gradual vs fairly rapid with the OEM ff attached to is normal location. As the OAT began to fall below 90* the corresponding VP44ift also fell an equivalent number of degrees. I do not know why 112* was the maximum temperature. When it did get to 112* it stayed there until the OAT started to drop and then it tracked the drop in OAT almost exactely.



Bob Weis

 

[keimmmo]

THANK YOU BOB!



I have been driving in mostly 70*-80* temps. Like I have been saying, the FF is warm to the touch, not hot. 112* max seems reasonable. After the FF I run the fuel through a cooler. Again, I have no way to measure actual temps, but the cooler is DEFINITELY cooler on the outlet than the inlet... usually pretty close to OAT. Without going back and looking at all the data, about how much did it drop the fuel temp to relocate the FF away from the block?



Bob, I'll bet I am pretty close to your original goal of 80*-100* most of the time. I don't see how it is possible to cool the fuel BELOW OAT, so it will be over on a hot day. And, there are no moving parts to give trouble and I still use the factory filter element and still have a fuel heater for when it gets cold... no need to make seasonal fuel system changes. (Other than maybe hang a piece of cardboard in front of the cooler in really cold weather. )



Modifications are something very personal. I know that. My system will not be what everyone wants. But, it seems to be working for me and I am happy with the modification.



Steve Keim

 

[rweis]

Well so far,



I have not towed yet, nor gone on all day high speed heavy loaded trip. The VPift (input fuel temp) seems to be about 15* - 20* above the OAT (with my system of a fuel cooler and fan and return to the vent line).



I am sure ther is some heat from the OEM ff eventhough it is hung on the master brake cylinder. I got the Canton ff, but have to get fittings for it to get ot my AN-6. The Canton will flow huge volume (90gpm, AN-12 inlet / outlet), I over bought its capability. There is a smaller one which would work fine for an ISB. I am going to mount the Canton down on the frame.



Once I get the fittings to get to AN-6 then there will be nothing in the engine compartment to abosrb heat into the fuel system and I will get actual VP work fuel temp rises due strictly to the VP effort. I can reduce return fuel temps by 10*. If the VP generates less than 10* fuel rise in temps then the system will be steady state.



Until the fittings come, starting next week I will run a week with a insulating strip under the OEM ff mount in the OEM loction and see what that does then a blanket around the OEM ff with the insulating strip mounts and see what that does. By then the fittings will be here (10/9).



I have been emailing with Gary about the after shutdown heat soak of the VP. He found his fan duct system seems to work well. Additionally puting a funnel in from of the fan so it does not pick up radiator heat seems to be one important thing to consider. So far his timer is set to 90 minutes which seems to be working well.



Bob Weis