On Wednesday I had been on the freeway for about 15 minutes and the engine just shut down and I ultimately got it towed home. I still had/have normal fuel pressure (about 20psi) and the computer appears to be working at least well enough for my code reader to connect but there are no codes showing. Battery voltages is good and the terminal connections are tight. I swapped the Fuel relay with the horn relay and it still worked and also did the same with the ASD and Security relays just in case. At this point the starter motor cranks nice and fast but the engine doesn't even try to start. I tried loosening one of the injector lines and cranking it and I'm not seeing any fuel coming out. Back in May I replaced the VP44 with a reman from DAP and until now it's been mostly good. I say mostly because over the last week or two I've felt that it might be down on power just a little but I've been chalking it up to high temperatures (long drives at high altitude with ambient temps hovering around 100 degrees.

Is there anything else I should be checking before contacting DAP?

Blue Chip Diesel has an excitant VP 44 diagnostic tests on their web site.

Blue Chip Diesel | Runing Tests

how many miles were on your injectors before you replaced the VP44? HOW fast is your motor turning over? I know you sort of answered this but I mean like faster than it "should"?? When I replaced my VP44 my injectors had (to my knowledge) 433k miles on them.... New pump, old injectors and I blew a hole through #5, still ran, 1 code, melted IAC sensor (that is what the code was for). Cummins (read it in a post, so don't quote me) suggests replacing injectors every 200k.... I"ve been told on forums that it should be every 100k miles.... JUST A THOUGHT... if you lost two cylinders it might not start at all and be SUPER easy to turn over.

100k miles replace injectors. By 150k miles your pop pressure will be too low and adding timing. So my factory injectors after 150k miles popped as low as 260 bar which is like a 5 degree advancement of timing and since it was early injection it also affected idle being the ECM was at 0% load and idling at 850-875 RPM because of injector wear.

Edited yesterday at 05:18 PM1 day by Mopar1973Man

1 hour ago, Mopar1973Man said:

100k miles replace injectors. By 150k miles your pop pressure will be too low and adding timing. So my factory injectors after 150k miles popped as low as 260 bar which is like a 5 degree advancement of timing and since it was early injection it also affected idle being the ECM was at 0% load and idling at 850-875 RPM because of injector wear.

could the change in timing be WHY #5 blew through the cylinder? I just presumed the new injector pump was putting out way more pressure than the injector could handle.

On 8/8/2025 at 1:51 PM, IBMobile said:

Blue Chip Diesel has an excitant VP 44 diagnostic tests on their web site.

Blue Chip Diesel | Runing Tests

Thanks, that link is a keeper. I followed it up until the "Hot Wire" test. So far all good but I'll work through the rest and see what I see.

On 8/11/2025 at 4:36 AM, Tim Waldo said:

how many miles were on your injectors before you replaced the VP44? HOW fast is your motor turning over?

I'm not sure how many miles are on the injectors. I bought the truck in the spring of 2020 and have put around 60k miles on it since. Total miles are 258k.

The motor is spinning over fairly fast however it's warm out, batteries are fairly new and fully charged so I think it's normal. I'm not hearing any uneven sound too it like one cylinder is different or anything like that.

Update.

I cranked it over for quite a bit longer and did eventually get some fuel out of the injector line that I'd loosened. Still didn't seem like as much as I'd expect but it was something.

Question, is there any chance the pressure relief valve (sorry I don't remember the correct name) could be stuck open and if so should I be able to tell by looking at the fuel pressure gauge (it's still the same 20psi that it always is when the pump is running).

8 hours ago, Tim Waldo said:

could the change in timing be WHY #5 blew through the cylinder? I just presumed the new injector pump was putting out way more pressure than the injector could handle.

Or the nozzle cracked. Then ive heard they can turn into a diesel powered torch pointed at the top of the piston. For the cost of the rebuild engine I'd rather change a wear item like injectors at 100k at the cost of 400 to 600 dollars vs. a engine rebuild.

Remember that nozzle goes from dead cold to hot in a very short time being the nozzle living in the combustion chamber. Only lubricant is the fuel (2 cycle oil is bonus lube 128:1 ratio. Just heat cycles can eventually crack a nozzle. I've even seen new injectors nozzles crack in a short time.

This is why a little warm up is nice but it still best to get rolling and keep your foot out of the throttle till 170°F coolant this will typically be about 140°F engine oil temperature at least on Beast.

If your using cetane booster you might want to stop that. High cetane actually reduces BTU content of the fuel. Some products actually could soot up the nozzles makes for nasty spray patterns. Here is where 2 cycle oil shines it actually keeps the injectors cleaner. Ill dig up the photo. This is 85k miles on my stock injectors. You can clearly see the holes.

Edited 15 hours ago15 hr by Mopar1973Man

9 hours ago, RayNAz said:

Question, is there any chance the pressure relief valve (sorry I don't remember the correct name) could be stuck open and if so should I be able to tell by looking at the fuel pressure gauge (it's still the same 20psi that it always is when the pump is running).

Well there is a reason a new injector pump comes with a new over pressure valve. which I believe opens at 14psi... so in MY opinion maybe turn down your lift pump a bit... I have mine set to 15 or 16 psi. Not that I think this would affect the condition you described. But I have heard that 18+ makes for a hard start some times.

I'm set for 18 to 19 PSI lift pump pressure on Beast for over 400k miles no problems. The VP44 shuts off its most likely the PSG unit died on top of the VP44. Yes it is possible to have a injection pump that has ZERO codes but be brain dead and will not start. Don't let thart little module blow you away. It only controls timing (advancement or retard) then the fuel pin to pull it out to start the enginee and control the fuel amount. There is a bit of diagnostic code in there to produce error codes. There is only the timing solenoid valve to move the timing. Then the solenoid to control the fuel pin.