maxwell

Last year you all offered a ton of great info and help when my VP-44 went on the fritz, got the new VP in and Truck has been running great until recently, left the house and the pedal went dead, engine was still running/idling but no acceleration, no stuttering or such as last year when the VP went bad.

Got right back to the drive way and the throttle seemd to work as needed, I parked it for a bit, I've had the after market BD Transfer Pump for a few years.
Today I attached a fuel pressure test gage to the port off the side of the VP pump and turned the key for the 25 second pump run, it read 18 psi, the truck starts right up but no pressure reading on the gage, only time I can get the 18+ psi on the gage is when the engine is off, though when idling / increasing RPM I do not get any reading.

Codes thrown were:
PCU = 1693
ECU = 0216 (something about injection pump timing?)

I also thought the transfer pump is supposed to operate all the time when the engine is running?

Thank You.

SIXSLUG

0216 is known as the death code. Unfortunately you may have cooked the vp with low to no fuel pressure.

You need to get a fp gauge to avoid this, it is a lot cheaper than a new vp.

The transfer pump should run full time to keep up psi during engine running.

Drag.

maxwell

Well heck, now knowing that the fuel transfer pump should run all the time, what would cause it to not operate when the engine is running? it provides 18+ PSI pressure but only when not running, at idle or above no pressure, I have the gage attached to the schrader valve port on the VP.

Thanks again.

maxwell

Would a dying VP cause my transfer pump to run intermittently or not at all? Bad signal to the ECM?

I get 18 psi when the engine is not running, using the ignition key/brief turn of the starter/25 second pump run, but as soon as I crank over the engine and it is idling the pressure drops to 0 psi, and the transfer pump doesnt pump fuel to the VP.

And I have the test pressure gage attached to the schrader valve on the side of the VP, and the fuel filter is new.

jrs_dodge_diesel

You need to get the pressure while the truck is running under load. A static pressure check without the engine running does not reveal much on the health of the fuel system.

The VP has nothing to do with how the lift pump runs. The lift pump is controlled solely by the ECM. The lift pump running intermittently can be a sign of impending lift pump failure, or a faulty electrical connection. My pump had the power wire wear through due to abrasion, causing my pump to drop out randomly. Eventually wore out all the way causing it to not work at all until I fixed the power wire to the pump.

P0216 is not the death code for the VP44. All that indicates is that the VP44 is unable to achieve full timing, usually due to low fuel pressure under load (when timing is needed most) or the VP44 is wearing out.

maxwell

Thank you!! Saturday morning I am going to start a hand over ahnd inspection of the wiring starting from the transfer pump itself, and then on to the relay and other connection where the stock pump used to be,

Right now I am tinkering with some wiring to attach volt meter tryng get some real time voltage readings as it is running.

Again Thanks.

KATOOM

This is how the fuel pump should operate.....

Turn the key to ON - fuel pump cycles for approx 2 seconds to assure system is primed. Fuel pressure should reach idle pressure level and then drop back to zero when pump shuts off.

From the ON position, merely bump the key in the START position - fuel pump should run for approx 25 seconds. Fuel pressure should reach idle pressure level and then drop back to zero when pump shuts off.

Crank engine - fuel pump should run on/off (to fast to notice) but result in fuel pressure approx half of idle pressure.

Engine starts -fuel pump will run continually as engine runs.

Now sometimes aftermarket fuel pumps are wired in so that they plug directly into the OEM lift pump harness. The problem with this is those aftermarket fuel pumps generally run at higher amp loads which places stress on the ECM port which powers the fuel pump. This can be a problem.

Some people experience situations where the ECM will no longer power the fuel pumps (OEM or aftermarket) and this requires having to wire into another keyed source. But no matter what or how or where, you MUST use a relay otherwise the amperage of the fuel pumps will overheat the keyed source. This is why most quality aftermarket fuel pumps come with a new harness and relay.

And yes, having an aftermarket fuel pump is much better than the OEM lift pumps. But not having a fuel pressure gauge is pointless because you have no way to know whats going on or if the fuel pump is even doing anything.

BarryG

Katoom has it right on the money as usual.

Now this wont solve your problem but it is an alternative to electric pumps. My truck for whatever reason would go through the stock pumps like candy and more than once took out my vp44. In fact I am on my 4th VP44. Seems every time my lift pump went out I was on a road trip in the middle of nowhere with no place to get a part for hundred or more miles but by then the damage was done and within a few months my vp would go, When this was going on Fass hadn't come out yet and the Airdog had just come on the scene with no track record. So I opted to put on a mechanical pump sold by DTT called the RASP it was a belt driven pump. It worked great however it increased the amount of plumbing involved. The higher the rpm the higher the pressure. The RASP is no longer sold but there are similar units out there such as the Glacier Diesel's Fuel Boss
Glacier Diesel Power | Diesel Truck and Tractor Parts | Dodge Ram Cummins Kubota | - Product List
When I put a cam in my truck I made sure to get one with the fuel pump lobe on it and converted the RASP to the block mounted 12 valve mechanical pump run off the cam fuel pump lobe. It bolts right up in place of the stock pump. I went through 4 or 5 lift pumps and 3 VP 44's before I put on the RASP. Since that time no more lift pump or vp failures (I have more mileage on my current vp than all others put together approx. 180k). I switched to the 12 valve pump really just to simplify the plumbing. The 12 valve pump is $100 of course the cam and install of cam added to that substantially. I only have 400hp so the stock 12 valve pump is more than adequate for my needs. I guess all this to say that if you in fact do need a new lift pump or your ecm pump wiring is no good I would look at the mechanical types such as the fuel boss as you will no longer need to worry about electricity, wiring, brushes in the motors, ecm etc (at least in regards to fuel pumps)as there aren't any and they don't cost any more than a full fass/air dog/fuel labs unit. They aren't for everybody I guess but certainly worth looking at if need be.

KATOOM

I love it!!!!! Not sure why more people dont do this.....aside from the part about the missing cam lobe. But if you were ever messing with the cam this seems like the most logical approach to all fuel pump options.

jrs_dodge_diesel

What's funny is the factory electric lift pump mounts on a plate, that covers the hole, where the 12V mechanical lift pump was installed.

I really wish that the factory cam would have had the extra lobe for the mechanical lift pump. Those diaphragm pumps are a very sturdy design. Heck, they were used for years on carbureted engines.

For those curious about the factory setup, here is how it works. The ECM uses a strong transistor as a switch to control the lift pump. For the most part, it is either turned on or off. During starting, the ECM modulates the transistors output to the pump so that the pump is only driven at about half speed (reduced pressure) for easier starting. I don't recall the specification off hand as to how many amps that it is capable of putting out, but it was more than enough to run the OEM pump. It's also enough to run a stronger pump like a DDRP. One problem is with aftermarket gerotor style pumps (like the DDRP), they can't handle solids like some other designs. So if the pump rotor gets locked, it will draw the most current (amps) continuously, and can overload/damage that part of the ECM circuit.

BarryG

Just in case anyone does do this and they see this thread a word of note. The 12 valve has a different mounting situation obviously than the 24 valve. On the 12 valve the pump sits farther away from the block due to the mount, fuel heater etc. Cummins makes a spacer for the removal of those items on the 12 valve. It is just a spacer that makes the pump sit about 1/4 to 1/3 of an inch away from the block. So it goes block, gasket, spacer, gasket, pump. You must use it as the pump plunger is too long otherwise.

maxwell

I finally had a the chance to go hand over hand to all my wiring to find if it was the cause to (perhaps) an intermittent running Lift pump. No broken or chaffed wires found, all connections good and not wet or broken.

Few years ago I put in a frame mounted BD Flow Max lift pump, it runs via a relay of which is actuated from the OEM (carter) lift pump connection.

Today I even disconnected the OEM connector put a meter on the OEM two wire connector and got 12.2 volts for 25 seconds after bumping the starter, reconnected to test the relay itself (for BG LP) and the relay works, (even bought a new relay to check and it works).

I still get 18 psi at the schrader port on the VP44, until I start the engine and then pressure drops to 0 psi on the gage, (gage also has a relief and I get no fuel out of the relief when running) but I can fuel flow out of the relief when engine isnt running.

So then I pulled out the relay and jumpered the hot wire so battery power went straight to the lift pump, so it ran ALL the time even without the ignition on. I did this to take the OEM / ECM out of the equation so I knew the lift pump would run no matter what.

I still had 18 psi to the VP44 with the engine off but when I started the engine the pressure dropped off to 0 psi again, since I know the lift pump was running at all times while jumpered I am a little puzzled why the lift pump cant keep pressure at the schrader port while idling, filters are fairly new and cant see any other obvious problems.

Can the lift pump actually be going bad? Bad enough to drop to 0 psi even at idle?

Should I be reading the pressure from some other point than the side of the VP44?

Apologies for the lengthy post, getting a bit frustrated with this.
Thanks to all.

P.S. I went ahead and drove the truck around and when on the road under very heavy acceleration or at above 60mph it "bucked" couple times like turning a switch on / off real quick, after a brief search it might appear that the Vp44 is not getting the fuel it needs ??

KATOOM

Kudos for checking the pressures at those various times but checking to see if there's actually 12 volts to the fuel pump when you're no longer getting pressure is what will answer your question.

maxwell

Thanks Katoom!

When I jumpered the relay (I took out the relay and jumpered the battery wire to pump wire at the relay socket) the pump started to run right away even with out the key in the ignition. This took out any factors from the ECM. Since the relay is energized from the OEM lift pump connector. Then once the relay is energized the pump runs off battery voltage.

So I was hoping the pump would run at all times even with engine running, cant really tell if the pump is running when engine is running due to the racket and general vibration and the pressure dropping off when I start the truck up.

I guess I will try to run some make shift leads from the actual lift pump connector to see if the voltage still remains to the pump when engine is running.

KATOOM

If the relay remains energized then the pump will stop. If you have a 5 pin relay that switches OFF when the key is in the START position then all you have to do is connect a test light to the hot pin and see if it remains hot when the engine is on.