What is the throughput or "spill rate" into the return lines on the VE pump? On my Benz it is significant (several times fuel consumption)
I'm wondering, if it is low enough, I might just run a heated filtered WVO system and the stock system and switch the post filter fuel input to the injection pump and leave the return alone just dumping the D2 residual spill back into the main tank where I will have the SVO.
That is to say switch the filtered input to the injection pump and for simplicity don't switch the return.
The VE pump seems to bypass much less fuel than more modern pumps. I measured the return flow once several years ago, from memory, the return fuel flow is about 2 1/4 times the amount of fuel the engine was actualy burning. At 60 MPH and 17 MPG the engine was burning 3 1/2 gallons/hour but there was actualy about 12 G/H flowing through the lift pump.
the reason I measured this was because the screen in the bottom of the stock fuel tank plugged completely up while I was 50 miles from home. I had a couple of 5 gallon jerry cans of fuel with me, I bought a 2 1/2 gallon plastic drinking water jug in a grocery store and used this as an under-hood supply tank. I cut the vehicle plastic fuel line along the frame and brought it up into the plastic jug under the hood, to my surprise I had to refill the 2 1/2 gallon jug 3 times to travel the 50 miles back home and used most of the fuel I had in the cans, I was getting about 17 MPG prior to this fuel screen plug-up so 50 miles should have used just a bit under 3 gallons of fuel, the extra fuel ended up in the vehicle tank.
Do you know anything about the "spill rate" of the injector returns?
It seems from your blog and my limited experience with this truck (89 D250), I have owned it for about 3 weeks and have had it running on 80/20 rug blend for a week, that it's most limiting features are the low pressure of the lift pump, and the 1/4" fuel lines from the tank.
As to the lift pump pressure vs the filter clogging issue:
How much pressure can the VE pump take at the input?
Do you think that it could take the 10 to 14 lbs. of the Airtex 8153.
I also have laying around Bosch inline gear pump from a BMW that puts out hose bursting pressure, have you encountered a low cost regulator with a bypass such that it could be run as a loop through the fphe and filter?
One reason that I am asking is that there is oil dripping down the side of the block from the lift pump. I don't know if it is crank case oil or fuel, but I think I may be in for a decision sooner than later.
injector return line -- This line is "T"d into the injector pump return line at the very rear of the block, just before the plastic return line to the fuel tank connects to the metal line on the block. The injector overflow is part of the 2 1/4 X return flow that I measured. I have disconnected this line with the engine ideling and did not see ANY flow from it, I suspect the flow from the injector overflow line is negligable even at speed.
Oil drip from lift pump area -- This will happen if the two pump mounting bolts are not tight, or the gasket is bad. Either one of these will let crancase lube oil drip down the block, I have had both things happen. If the diaphragm leaks you may not see it from the outside as the fuel will likely run into the crancase opening, about the only indication of a leaky diaphragm will be loss of fuel milage and a rise in the level of the lube oil.
VE input pressure -- From what I have read if the input pressure gets much over 10 pounds you will possibly blow the front shaft seal out of its seat but I don't have any actual experiance. I don't think the low pressure is a problem for this pump, it has it's own internal vane pump that makes upwards of a hundred pounds pressure to feed the main plunger portion of the pump, as long as you get fuel into this internal pump it automatically takes care of feeding fuel to the high pressure section. The 4 cylinder Volkswagon version of this VE pump does not even use a lift pump, it sucks fuel directly from the tank.
1/4 inch fuel lines -- Yes, from my experiance these are a limiting item with thicker veg if the temps get down below about 50 deg f, the top speed may be limited under heavy load and cool conditions. Down around freezing the engine may idle very slowly and it will likely bog badly when the accelerator is either pressed or released, under the right temp conditions I have only been able to run up to 30 MPH for 10-15 minutes until the hotter return fuel thinned the fuel in the fueltank pickup canister, (the return fuel drops back inside the fueltank fuel pickup canister so it heats the fuel in the canister) sometimes even that didn't help. On one winter trip through north Texas burning 70% veg/30% diesel I shut down for a few hours over night, it got down around freezing and the next morning I ran 45 miles with my foot to the floor doing 30 MPH until I found a gas station with diesel, I added a few more gallons of diesel to the 100 gallon tank of cold thick blend and was back up to speed within a few miles.
Replacing the screen in the stock fuel tank with one that is more course, and increasing the fuel lines to 3/8 I.D. all the way from the bottom of the tank up to the lift pump, has eliminated these fuel line restriction problems.
The screen in the bottom of the fuel pickup canister in the fuel tank is EXTREMELY fine, I replaced it with much more corse window screen. The fine stock screen also plugs up with even a thin coating of solidified grease, I dropped the tank twice due to a thin 1/64 inch layer of lardlike stuff covering the screen, the second time is when I replaced the fine screen with the corse one. There are pictures and more details about this on page 2 of this discussion.
Fuel pressure regulator -- Sorry, no experiance with these. Reading about some of the external pressure regulaters for fuel pumps most seem not to use a return line somehow, these seem to restrict the flow and cause the pump to work extremely hard, this causes the electric motor to draw max current and heat up?
This links to an 8 page past discussion about "reliable electric lift pumps", may be some usable info there?
Last fall I replaced the rigid steel 1/4 inch I.D. fuel line between the output of the stock fuel filter and the input of the injection pump with 3/8 rubber fuel hose, this was to allow easy fuel line connection to fuel switching solenoid valves. I have not yet installed the valves so have about 4 ft of rubber fuel hose between the outlet of the fuel filter and the input to the injection pump (made custom 3/8 I.D. hose barbs for both). I now have to crank the engine over for a LOT longer to get it started than with the shorter solid steel line, especially if the truck has set overnight or longer. Not sure, but I may have a leaky check valve in the lift pump that allows the pressure to leak out of this hose over time so the engine has to turn over 20-30 times for the camshaft driven lift pump to repressurize the hose, I also suspect the hose stretches a bit so it takes even more time to pressureize. The hose I.D. is also 3/8 inch rather than the original 1/4 inch so it takes twice as much fuel to fill it before pressure starts to build. This sort of contradicts my earlier statment about the VE input pressure needs? I will do some testing next spring by temporarily replacing the diaphragm pump with an electric one of similar pressure, if the truck starts normally after giving the electric pump a few seconds to build up pressure I will have a better understanding of this problem. I may have to switch permanently to an electric pump if this solves the starting problem as using rubber hose is the most practical way to plumb up the fuel valves. BUT - the problem may actually be an injector fouling problem, the truck was getting a bit harder to start even before this change, I thought it might be caused by injection pump wear as the one on the truck has well over 220,000 miles on it. BUT - A friend here with a 92 7.3 diesel Ford had similar staring problems and new injectors cleared it up, won't know til spring, I parked the diesel truck for the winter since gas prices dropped.
Would this stuff work to connect up with hose to get around the steel pipe associated with the VE pump? Some is 5/16 and some is 3/8. it is 12mm stuff salvaged off a dead Benz in a local junk yard.
mbz_banjo_misc.jpg (47 Kb, 67 downloads) Misc junkyard MBZ banjo fittinga
Sort of dought if these banjo fittings would work without leaking, the threaded fuel inlet hole into the VE pump appears to be a straight 12MM X 1.5MM thread (from memory) but the diameter of the threaded hole is oversized by several thousanths for some reason so whatever you screw into it is a loose fit, you have to use a sealing washer under a flange on whatever you screw into this opening to keep it from leaking, the original 5/16 steel tube compression fitting used an aluminum washer, I used a 1/16 inch thick teflon one under a drilled out brass washer.
The length of the threads on the banjo bolts in your picture are not very long so they would fit even looser in the pump inlet than the 5/8 inch long threaded fitting that I used, it still rattled around in the threads until it was tightened down. Another thing is that banjo fittings are very restrictive to thick fluid, the total area of the side holes in the center bolt is usually much less than the area of the center hole, you might be able to drill the side holes larger successfully, don't know. I suppose you could use the factory 5/16 O.D. steel tube as a hose barb by cutting it off a few inches before the pump, this would allow you to use the stock steel tube and it's fitting into the pump. I had to cut this tube off just above the fitting in the pump anyway to be able to use a deep socket to get the stock fitting out of the pump, just not enough room to get wrenches in place to be able to loosen the compression nut on the top of the fitting, at least I never figured out how to do it.
The problem with cutting the inlet steel tube to make a hose barb is how do you prevent chips from entering the pump?
Use a tubing cutter - the kind with a sharp rolling wheel. At all costs, do whatever is necessary to keep chips and dirt out of the fuel system.
Copper crush washers can be reused if they're annealed first. Heat from a propane torch works nicely. Set the washer on an anvil/solid metal surface, then heat until it changes color, then let cool naturally. It will then conform and seal easily, without over-tightening.
Cutting tube without making chips -- There is not enough room to use a tubing cutter or anything else normally used to cut tubing so I simply used a pair of heavy duty wire cutters to mash the tube completely closed on the engine side of where I wanted to make the cut, then used the big cutters to chew my way through the tube on the filter side of the "mashed shut" location.
Once you get the stock fitting with the stub of tubing out of the pump you can then get to both the hex portion of the fitting body and also to the hex compression nut, use wrenches to remove the nut and tube from the fitting, then use a new piece of tubing and a new compression "olive" to make up whatever type hose barb you prefer.
Ah, I get it. I assumed the tube was removable, or should I say "easily" removable. I too have used the giant-nipper-method to cut tubing in-place. Ick.
I'm just curious, my lift pump priming lever seems to have no resistance except for a very light return spring, is this normal, or is it indicative of a faulty lift pump?
I ask this because I know no one with a first gen cummins with which I can compare..
lars -- A couple things about the lift pump lever, first, the pump is normally pumped from an internal lever that rides on a lobe on the engine camshaft, if the engine stops in such a way that the cam lobe has the internal lever depressed there will be almost no pressure on the external lever and it won't make the pump move any fuel, bump the engine starter just a bit and see if the pressure on the lever increases. Even when the lever causes the pump to move fuel the lever will still not move hard as the lever does not actually pump the diaphragm, it only retracts the diaphragm against it's 5 pound pressure spring so there won't be any increase in the pressure required to pump the lever.
You can test if the lever is pumping fuel by removing the small 10 mm blead screw that is in the center of the banjo fitting on the steel fuel tube that runs up to the injection pump, this fitting is located in the side of the head just above the stock fuel filter, pump the lever and see if fuel flows out. This fitting is on the output side of the fuel filter so the filter has to be full of fuel before anything will flow out of the fitting.
Thanks for the info.
I cured the oil leak by loosening the two bolts that held the lift pump and working in a small bead of silicone and re tightening.
The lift pump checked out fine once I loosened the bleed screw, got some air out of the top of the filter, which I hope will explain why I was intermittently having longer cranking sessions to start despite the engine being up to temp. I wonder what is causing the air, doesn't it have an air separator, or recycle it back to the tank?
Currently running n 80 wvo 20 rug with PSDK.
I had to adjust the slow idle by shortening the linkage on the drivers side of the lift pump to get the idle up. I couldn't figure a way to get at the idle stop screw on the far side of the VE pump.
The weather here has gone up to the 80s over the past few days, but was in the 20s a couple of weeks ago and it seemed to run fine as long as the block heater was used before the first start of the day. Same as with diesel.
I am now setting up for a 2 tank system and have scrounged most of the parts except for the transfer valve. I have already cut into the coolant system and set that up.
VE injection pump idle adjust tools --
I modified a 10mm 12 point box end wrench so I could loosen/tighten the jamb nut on the idle adjust shaft, I kept heating, bending, and grinding away til I was able to just get the wrench to move enough to get one of the 12 point sections with each try, had to grind the wrench very thin and bend it in a couple places to get enough clearance to use it.
I never did figure out how to get a screwdriver into the slot on the end of the idle adjust shaft but the shaft has a cross-drilled hole that I use to turn it. I suspect this hole was originally intended for safty wire but by using a small sharp pointed screwdriver type 90 deg pick it can be turner 1/2 turn at a time. The pick is from a $2.00 set from Harbor Freight.
This pic shows how the wrench was ground away.
1-_shaped_wrench_and_pick_-_flat_view.JPG (28 Kb, 55 downloads)
This pic shows how the wrench is bent.
1-_shaped_wrench_and_pick_-_side_view.JPG (29 Kb, 42 downloads)
How much pressure can a Bosch VE rotary pump take at the input?
These are found on some VW diesels and 1st generation Cummins.
On the Dodge they have a 5-7 psi lift pump, and the VW has none.
I have an 89 D 250 Cummins.
I have been looking at the Airtex 15 psi electric pump with an eye to setting up a 2 pump system and switching the returns.
I would like to run 15 psi for filter life.
I have been told that by Tim that 10 psi is the limit before blowing seals, but have heard about higher pressure Bosch piston pumps being used. I know from experience with my '80 Mbz that these can put out almost 20 psi under certain circumstances.
I have called the Cummins tech without result.
Can any one clarify this issue.
Just spoke to Cummins support guru who confirmed Tim's statement.
I received an email request for further info about a post I made a few years back about adding an electronic tachometer to this 93 vehicle. The 93 Dodge Cummins was the first year the vehicle had a computer, the vehicle did not have a tach option from the factory but the factory manual I bought does show a 4-pin connector for one. I found the connector bundled up in the wiring bundle just under the bottom lip of the dash at about where your left knee ends up. I never did find the correct mating connector so I cut the factory connector off and went with individual bullet connectors. I bought about the cheapest electronic tack I could find and it has worked with no problem other than the erratic readings from the computer at cold startup.
The 4-pin connector has a black 18 gauge wire on one end that is GROUND, next to this black wire is an ORANGE 20 gauge dash lamp wire that has 12 volts switched to it when you turn on the headlights, next to this orange wire is a RED 18 gauge wire that has 12 volts switched to it when the ignition is turned on, the 4th wire is a GREY 20 gauge wire with a LIGHT BLUE tracer stripe, this wire comes from the computer and goes to the tach signal input, it has the 5 volt pulses that drive the tach. The tach pulses are from the computer, the computer gets its RPM info from a solid state pickup that makes pulses from the front crankshaft balancer. Set the tack to the 4-cylinder engine position and it works fine except at idle when the engine is warming up, the tack bounces around a bit during this time, I think the reason for the erratic behavior at cold startup is because the computer is busy watching all the sensors and misses some of the rpm pulses.
The email also asked about the mod I made to the vehicle wiring that took the control of shifting the auto trans into overdrive away from the computer and allowed the OD shifting to be controlled from a manual switch on the dash. This has worked fine but not quite in the way I had expected it to. Part of the control of shifting into OD is done hydraulically inside the trans, it must be in high gear before it can shift into OD, and once it is in OD, and the manual switch is on, it does not drop out of OD until the trans drops out of high gear, this is true even if the accelerator is floored, if you need to drop a gear for passing you have to turn off the switch manually. When you are slowing for a stop sign with the OD on it does not drop out of OD until you slow to around 7-8 mph and the trans downshifts to second gear while slowing to a stop. if you take off from a stop with the OD switch on the trans upshifts from first to second to third normally but you get a double bump when shifting into high gear because it shifts into OD at almost the same instant the trans shifts into high gear. Because of all this I just turn the OD switch off when in town or stop-n-go traffic.
A bit of background ... The computer does not control the engine in any way but it does make decisions about many of the accessories, it turns the alternator on/off as well as making decisions concerning allowing the auto trans to shift in/out of overdrive, it also turns the air conditioner compressor clutch on/off. If the auto trans and/or the radiator overheats the computer drops the trans out of overdrive and will also start shutting off the accessories until things cool down (PITA). Part of the wiring change is to send a false signal to the computer telling it that the trans is not overheating, if this is not done the computer won't let the air conditioner run.
The computer also monitors the engine rpm, the transmission speed sensor, and the throttle position when making all these decisions. I never could keep the throttle position sensor in adjustment and the computer never did allow the trans to stay in overdrive in a manner that I wanted it to, it shifted at the wrong time going up/down long hills, it would even drop out of OD if running against a stiff wind, VERY aggravating.
The wiring mods are not extensive, mainly just rewiring the existing wires down close to the trans. The transmission has a normally-closed temp sensor switch attached to the steel oil tube that moves tranny fluid up to the oil coolers, I kept this temp switch in the wiring so the trans would automatically drop out of OD if the oil ever did get too hot, I have yet to have it overheat but I wanted some kind of indication if it ever did, downshifting seemed like a good indicator.
This 93 vehicle auto trans only has overdrive, it does not have the locking torque converter that was added to the 94 model trucks. the "OD ONLY" trans has 2 wires going to the electrical control connector on the side of the trans, the "OD and LOCKUP" trans has 3 wires to it's electrical connector.
The wires go to electrically activated hydraulic valves mounted internally on the valve body, these solenoid valves control the flow of pressurized hydraulic oil to do the actual work of engaging/disengaging the OD clutches located in the tail shaft of the trans. One of the wires is a ground and the other wire(s) power the solenoid valve or valves.
I made this mod several years ago and my drawings of the changes are not as good as I had remembered so it will be a few days before I get them figured out and posted.
Second attempt to fix the fuel tank sender -
Made a trip from Illinois to Arizona a few weeks ago and someplace along the way I lost the rear brake function on the truck. Turned out to be the funky rear ABS accumulator /solenoid unit mounted on the frame just behind the rear axel. Reading about these on the net it seems that this early RABS setup never worked well even when they were new. this truck has had spongey brakes since I got it so I decided to bypass the ABS system by shortening the brake line to the ABS valve and connecting it directly to the rear axel (details and pics shortly), this required that I drop the fuel tank.
The fuel sender only work for a couple days when I repaired it before, turned out I screwed up reassembeling it the last time, I didn't get the rotating slider unit placed under it's retainig lip so the rotating slider assemly and the float had fallen completely off the sender - Egg on my face...
I thought I would replace the sender unit with a new one, expected it to be a bit costly, past web postings on other sites had stated from $40 to $80 dollars, called Jim Glick dealer parts counter in Tucson today, they quoted a price of $109.98 for just the sender. - decided to try one more repair.
Searching the web I found a couple of repairs posted by other folks. THIS ONE describes shortening the center rotating portion of the slider assembly so a push nut can be forced over the slider's pivot pin. THIS ONE has pictures and he made a new longer pivot pin and added a spring to hold the rotating slider assembly in better contact with the sender's resister board. He did a good bit of machining in this mod but I liked the idea of using the spring.
My approach uses a 4-40 by 1.5 inch long SS machine screw as a new pivot post, no machining required and only a small bit of hand held drill bit work to ream out a couple of holes, one is to enlarge the recess in the back of the sender assembly to accept the head of the screw, the other opens up the hole through the rotating slider assembly slightly so it pivots freely over the 4-40 screw threads. By adding the spring the rotating slider assembly is pushed into firm contact with both the resistive contacts on the ceramic resistive element board and also the "common" (ground) sliding contact found inder the central pivoting section of the slider assembly.
For referance - This picture shows the rotating slider assembly removed from the sender.
rotating_slider_assembly.JPG (18 Kb, 26 downloads)
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