Lift pump diagnostic help needed

[Mopar1973Man]

If the ECM stays powered up you have the same thing happening.

 

Actually it designed that if the ECM no longer sees a crank signal to shut down the fuel pump.

[rancherman]

It must be internal to the pump because it hooks up just like a fass or a raptor.

this  was   kicking my rear,  so  I went  straight to the  source!

 

Josh @  fuelab    says:

We use a DC brushless motor. Most of our pumps (all of the inline as well the 200gph diesel) have three terminals- power, ground, and speed control. If the speed control terminal is grounded, the pump will be in reduced speed mode (depending on pump model 50%-70%). If you take the ground away from the speed control terminal, the pump will operate in full speed. You can obviously control this with just about any kind of switch you can think of- toggle, boost, rpm, etc. If you want variable speed out of the pump rather than just high/low, you can send a 500hz-1500hz PWM signal to the speed control terminal. We also have an electronic fuel pressure regulator for EFI applications that will give you variable speed out of the pump based on what the regulator sees in the return line (essentially, the pump is commanded to only run as fast as it needs to in order to maintain whatever base pressure you have set). Our 100gph diesel kits are only single speed though.

 

Let me know if you have any other questions.

 

Thanks,

 

Josh Davis

Marketing, Sales, & Tech Support

 

 

 

Edited January 22, 2015 by rancherman

[hodag56]

Thanks  for the info.

 The only reason I noticed this   was because when In installed my Fass I could only get the lift pump to power for 1 sec , without jumping the relay, regardless if I turned it back to run .(I jumped the relay on the lift pump to get  fuel to the i.p. )If for some reason it doesn't fire right away( which doesn't happen very often ) I have to turn the  key to off and start over ,where before   the lift pump would run for 25 sec by turning the key to run. Now as soon as the engine fires the lift pump ,which I assume is getting power thru the ecm via the idle validation circuit .Perhaps  I am over analyzing this.

Edited January 22, 2015 by hodag56

[dave110]

OK so I have my LP wired to the wiper fuse and it runs as soon as the key is in RUN. My truck does not seem to like to start that way. I wonder if pushing 18psi to the IP for the 30sec or so it takes the grids to cycle is not good? Starts kinda hard warm when it sits for 10 min or so. I put a test light on the factory LP wire which the Raptor uses for a relay trigger and found out that the clunks I was hearing match the light pulses. So when I bump the starter the test lite goes on, off,on,off,on,off and then sometimes stays on for the 25 sec and sometimes stays off. Also when I key on sometimes it lites for a second and sometimes not. When the engine is running the lite is always on. I figured this was the case because I never lost fuel pressure when driving. So the ECM is not turning the LP on like it should. WHY? I like this truck but I never know if it's gonna start or not. Blue Chip IP is only 3 months old and runs great. Why isn't my lift pump turning on correctly?

[Mopar1973Man]

Oh I see a neat trick with that. Using a 5 pin relay you could trigger the fuelabs from the starter solenoid to be half rate during cranking and full rate at run position. Then you can rid the entire ECM control if need be. But remember the ECM safety of shut down after lose of tach signal will not occur.

[dave110]

Would you still get a 2 sec prime at key on and 25 sec run at starter bump?

[JAG1]

Would you still get a 2 sec prime at key on and 25 sec run at starter bump?

 

Related to the above.... Does it hurt the VP if you start the engine without fuel pressure?

Edited January 23, 2015 by JAG1

[Mopar1973Man]

The key on pulse is not required.

 

But at cranking pressure should be 7-12 PSI for good starting.

 

Then after starting it should be 14-20 PSI after starting.

 

So the relay trick would resolve a ECM lift pump controller. But as for 25 bump prime would be gone as for the safety shut down. But I know some people have damaged ECM and using wiper fuse to power the lift pump this would get you closer to the original design just missing a few things. I'm sure with a bit a time you could add a push button switch to give your 25 second lift pump prime set up.

[rlane547]

Related to the above.... Does it hurt the VP if you start the engine without fuel pressure?

Since the VP44 uses fuel for lubrication, I would say that you would not see any effect right away but starting the engine over and over thousands of times without fuel, would cause the internals of the VP44 to wear at a faster rate ultimately resulting in pump failure.  Mike, please correct me if I'm wrong here.

[JAG1]

I'm not sure it's that just I've understood, for some time, that the VP is capable of pumping some fuel from the tank and you only need cooling when underway and it starts building heat.

[dave110]

The key on pulse is not required.

 

If not why did they make it that way? A little bit of drain back, which I know does not happen in the perfect world, and the prime is necessary to give the VP fuel at starting. So back to topic, why is my LP getting sporadic pulses from the ECM??

 

Edited January 23, 2015 by dave110

[dave110]

Copy /paste is impossible?  If key on pulse is not needed why was it made that way? A little bit of drainback , which I know does not happen in the real world, and the prime is necessary to give the VP fuel at startup. So back to topic why is my LP getting sporadic pulses from the ECM?

[hodag56]

I 'm not going to mess with the trigger wire to my lift pump relay As long as it gets pressure when I bump the starter and it fires right up. I may take it to the dealer and have my ecm flashed being I've never done it since I had my ecm rebuilt. My mileage is down about 3 miles per gal, but it's sure got good power an it shifts good and firm.

[Mopar1973Man]

Since the VP44 uses fuel for lubrication, I would say that you would not see any effect right away but starting the engine over and over thousands of times without fuel, would cause the internals of the VP44 to wear at a faster rate ultimately resulting in pump failure.  Mike, please correct me if I'm wrong here.

 

Kind of like saying you have increase wear from starting the engine without oil pressure. These truck start and run the first few seconds without oil pressure typically and go a long ways. So the VP44 is flooded with fuel for the parts I really don't think wear is a issue till its ran for a period of time without pressure.

[rlane547]

Kind of like saying you have increase wear from starting the engine without oil pressure. These truck start and run the first few seconds without oil pressure typically and go a long ways. So the VP44 is flooded with fuel for the parts I really don't think wear is a issue till its ran for a period of time without pressure.

You're right. It's ultimately the heat from the friction that causes the wear. That length of time wouldn't produce enough heat to damage anything. There goes my hypothesis.

[dave110]

The key on pulse is not required.

 

Why was it made that way then? Curious

[Mopar1973Man]

Key on pulse is present in some models and not present in others. Just depends on how the software was wrote. But serve no purpose that I know of. The pulse is too short to prime the VP44 or even flush the heat from the VP44. Very little of fuel will trickle out of the overflow line even with a 25 second bump. Like I said it serves no real purpose. The only time the fuel is actually moving through the VP44 is when the engine is turning.

[hodag56]

Key on pulse is present in some models and not present in others. Just depends on how the software was wrote. But serve no purpose that I know of. The pulse is too short to prime the VP44 or even flush the heat from the VP44. Very little of fuel will trickle out of the overflow line even with a 25 second bump. Like I said it serves no real purpose. The only time the fuel is actually moving through the VP44 is when the engine is turning.

Thanks Mike,

When I turn  the key to run and then start I always have about 3 or 4 # pressure on my gauge , but the engine fires immediately and pressure jumps to 18 #.This truck

runs better now than it did when it was new, but my mileage is terrible (about 11 in town and15 on the highway.)

[dave110]

So for the last week the truck has worked perfectly. Key on, 2 sec. LP run, fire right off. Until today. I made 3 stops after the truck was up to temp. First 2 no problem, LP run at key on and instastart. On the 3rd stop key on and no LP run and no start. Key off and on again and I noticed the WTS lite was on and it shouldn't have been because I was at full temp when I shut it off. I waited til it went off (5-7 sec.) and then it started. Made another stop and no LP at key on and WTS lite flashed on & off a few times and then started. Whenever I don't get the LP run at key on I can pretty much bet I'll have to crank 10 sec. to get it to start and whenever the LP does run on key on I can pretty much bet it will start instantly even on a 10 degree morning unplugged. Assuming the 2 sec. LP run at key on is not needed what do I have going on here? This is only when engine is hot (so far) and wiring to the wiper fuse made no difference.

[dave110]

Just an update for those who may be following. I pulled the plug on the ECM. The screw that holds it in was loose. I did Yankneck's trick with the dielectric grease and cycle'd the plug 3 times and put it back together and it's been perfect since. I'll keep saying my prayers.....