Raptor Lift Pump Issues?

R

Redrider2911

New member
So i just bought my first electronic injected diesel. Guy said he couldn’t get it started. Thought lift pump was bad, installed a raptor lift pump (in the stock location on the drivers side of the block?) looks like there is new quick disconnect lines between the raptor pump and the VP44 but he used the stock lines between the tank and the Raptor. Is this normal?

So anyways. After properly bleeding the fuel system, resetting the APPS, and trying to do some trial and elimination; The truck won’t even start with the lift pump on. Disconnected the power and it fires right up and idles smooth, but will sputter when reved like it’s starving for fuel. Reconnect power back to the Raptor pump and the truck immediately starts to miss and almost dies. Kill power to it, it smooths out in about 20 seconds.

Tried adjusting the loressure screw all the way in and out. No difference. The tank gauge is on Full. But i know these go bad. I’m going to grab 5 gallons of diesel and put the suction line right into it to fully rule out air leaks.

Anyone else have some ideas?
Thanks.
Kris
 
I had the same issue once, try running power to the lift pump straight from the battery once. My harness ended up being bad, why it made it act the way it did I'm clueless

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thatguy69 said:
I had the same issue once, try running power to the lift pump straight from the battery once. My harness ended up being bad, why it made it act the way it did I'm clueless

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Click to expand...

K. Well i guess I’ll try that tomorrow. Going to hook up a pressure gauge too. What about the sputtering when revving without the pump hooked up. Is that normal?
 
Do not run the truck without the lift pump. That's a really good way to burn up the injection pump.

Do you have a way to verify fuel pressure?

Did this truck have a lift pump on the block? Some trucks have been converted to in tank. If there is any chance that there is an in tank, then you must remove it. Otherwise it will be a restriction.

Also one problem with aftermarket pumps is that the VP44 does not like seeing much pressure during cranking. If the raptor comes on and raises fuel pressure too high during cranking, then the truck will not start. There are a few ways to run an aftermarket setup without having this problem.

Below are a few steps to verify if the raptor is running.


Hook up a fuel pressure guage and bump the ignition key. Do not start the truck. See if you are getting pressure and what it is. See if it jumps to a pressure or if it builds some pressure and then jumps again.

If you are seeing pressure then the following steps may not be necessary. If you are not seeing pressure then proceed through these steps.


Unhook the raptor from the from the injection pump and the tank lines. Run the tank/input side to a can/bucket/tank of clean diesel. run the VP44/output side to an empty container. Supply 12v to the pump and see if it pumps fuel. This isolates the raptor entirely from the systems on the truck.

If it pumps fuel, connect the input side to the tank line and repeat. This tests your feed line and tank pickup.

If it pumps fuel, hook up the output to vp44.
 
you cannot run the raptor off the ecm plug for the stock pump. that will fry the ecm eventually it pulls to many amps...it need to trigger a relay to make the raptor run.

my pump makes 25 psi never had an issue with startup pressures but have heard that...

sounds like its pulling air..get rid of the quik disc. clamp the lines to the fittings.
 
What the last 2 guys said, for sure. You've gotta be able to see pressure at the inlet banjo of the VP. I have a piece of clear 3/8" and 5/16" hose at the shop to replace lines with, just to check for air. I've yet to catch one getting air sucked in. Also, there is a relay providing power to the raptor, correct?
 
Thanks guys. That will give me a direction to go today on break and after work.

Had I put this pump on I would have added a relay, put a sump on the tank, and mounted the Raptor as close as possible to the tank and ran 1/2" line all the way to the VP44. Obviously they didn't care about what they were doing.

As far as I can tell, they thought this lift pump was a plug and play affair. I don't THINK this truck has the pump in the tank, it appears the Raptor is mounted to an OEM bracket on the side of the block. The only new fuel line is a blue soft line between the Lift Pump and the VP44. And I didn't see a relay when I was poking around yesterday. It appeared as if the raptor plugged directly into the OEM harness. I'll also figure out how to rig up a pressure gauge today.
 
My dads truck had this issue similar to this, it was a broken jumper wire for the Fuel relay in front he PDC as soon as the lift pump relay closed it shorted the engine relay
 
Justappumped24v said:
My dads truck had this issue similar to this, it was a broken jumper wire for the Fuel relay in front he PDC as soon as the lift pump relay closed it shorted the engine relay
Click to expand...

The "fuel system" relay in the PDC? Isn't that only for the VP44? I originally took that relay out and jumped it thinking it was for the lift pump, but all I heard was a click that sounded like it came from the Injection pump?
 
Ok. So i didn’t have all the fittings i thought i needed to rig up a pressure gauge. But i did have some 1/2” clear hose. Got all the air bled out of it by running the lift pump and then pushing it on the fitting and tightening the clamp. Great. Start it without the lift pump. Starts up, idle smooths out, no air in the line. Turn on the lift pump, immediate inrush of cavitated diesel. Hmm. Ok. Bypassed the fuel filter and went straight to pump outlet. Did the same thing. Put the lift suction into a 5 gallon can of diesel. Did the same thing.

Are these Raptors known to draw air? What’s weird is that if i leave the lift pump on, it seems to quit cavitating and the line clears up but the idle is still all loping/missing even after i bleed the injectors.

Note. Above tests were done with the lift pump jumped straight to the battery. Even tried jumping pin 6 and 7 on the VP to the battery and that didn’t seem to make any difference. Only other thing i noticed is that the pump is mounted on its side when the raptor directions say to mount it upright.
 
Just checked and the pump is Not running backwards. Found a 1-80psi gauge laying around and was able to rig that up. Unless that gauge was bad, i have 10-15psi of fuel. I definitely have some sort of positive pressure at least because i can see it bump up when i turn the lift pump on.

I going to try to find a gauge with lower range to be more accurate, but I’m not convinced the lift pump is the problem....

I did read on Blue Chip’s website that if you have problems with it running with the lift pump on, the diaphragm could be torn in the VP?... anyone have details on that?
 
One of the things that makes it harder to diagnose is that you don't know the true history of the truck, the vp44, or thee injectors.

Typically vp44 trucks with stock to mild injectors, will idle smooth.

The air/cavitation issue you are seeing is not typical, though it could be due to bleed back and its taking it a minute to clear up.

Any chance that you could take a video or sound clip and post it?

It is possible to have a bad VP44 without having a code. I'm not trying to sound like Mr Doom and Gloom. I'm just stating a possibility.

Also, if you crack the injector lines one at a time, does the sound change any?
 
I had a ad150 one time hat got real noisey. Girlfriend noticed it in the truck. And would pressurize he tank. Take the cap off and it would blow it off the tank. Got another one and issue solved. It was the pump cavitating the fuel when it ran.
 
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