ISX: Wanna come to Virginia for a weekend?

[Rogan]

ok..

[stodg73]

It seems that rogan needs some better explanations than"got it done in less than 15minutes". I would like one as well. Thanks

[ISX]

That's why I said worry about the fuel pressure gauge for now. The pumps without the retarding notch are easy enough but theres a hole that the delivery valve seat covers and I think it's just a return for fuel that leaks out around the delivery valve but I want to understand it more. I have a bunch of books from bosch that I am still going through and have just started getting to the pump section. I am going to take the pump off my truck today and then go back to my place so I can study it some more. In other words, I'm not blowing you guys off I'm holding out for the ability to explain it more. These aren't like CR's where you just change the number

[ISX]

Got the pump out of my truck from hood open to having the pump on the floor in 40 min. First time I have ever timed doing it. Still just as heavy as always. That thing needs to go on a diet.

[dorkweed]

How do the 12valvers advance timing with increased engine RPM???? It's a mechanical advance, correct???? If Rogans truck falls flat at higher RPM, maybe something is off, or broken, or stuck in the advancement mechanism.Just typing out my butt here!!!!

[Rogan]

I didn't think you were blowing me off. I need to order a banjo bolt for the tapped piece. I cannot find the VP bolt I had :(There is a banjo bolt with a secondary plug in the top, on my pump. Its on the front-side of the pump on the return line I believe. I didn't get an chance to check the thread size of the plug screw, nor did I hat to determine if it and the supply banjo bolts are the same size. Maybe tomorrow. Sent from my SPH-L710 using Tapatalk 2

[ISX]

How do the 12valvers advance timing with increased engine RPM???? It's a mechanical advance, correct???? If Rogans truck falls flat at higher RPM, maybe something is off, or broken, or stuck in the advancement mechanism. Just typing out my butt here!!!!

No they are completely static. Timing is always the same.. Thats why I was thinking fuel pressure since low fuel pressure is noticed higher up when it needs more fuel.

I didn't think you were blowing me off. I need to order a banjo bolt for the tapped piece. I cannot find the VP bolt I had There is a banjo bolt with a secondary plug in the top, on my pump. Its on the front-side of the pump on the return line I believe. I didn't get an chance to check the thread size of the plug screw, nor did I hat to determine if it and the supply banjo bolts are the same size. Maybe tomorrow. Sent from my SPH-L710 using Tapatalk 2

That is the overflow valve, don't touch it (for now, it might be the culprit though). It has a spring and ball in it which come out if you take the bolt inside the other bolt out. The one I am talking about is on top of the fuel filter, though looks a lot like the overflow valve one. Maybe you have the old style fuel filter. What I did was took the banjo bolt on the side of the ppump and put it in a lathe and drilled and tapped it for 1/8" NPT.

[dorkweed]

How can the timing not change with RPM????

[ISX]

Physically it all stays the same. The top of the plunger is FLAT (cept for my retarded 215 pump but we will ignore that) meaning it always has the same start of injection. They vary the end of injection to change fueling so the duration is longer but always starts at the same spot. This is why everyone is constantly messing with 12V timing... Trying to find that sweet spot between startability/drivability/power/etc.

[MnTom]

Rogan, chances are the overflow valve is weak. That is what sets your fuel pressure. If there is not enough fuel pressure then it will literally run out of fuel at higher RPMs. You could go to Cummins and get another one or just for grins and giggles pull the spring out and stretch it a little (should be about 1/2" long).

[Rogan]

Rogan, chances are the overflow valve is weak. That is what sets your fuel pressure. If there is not enough fuel pressure then it will literally run out of fuel at higher RPMs. You could go to Cummins and get another one or just for grins and giggles pull the spring out and stretch it a little (should be about 1/2" long).

I have a new Bosch one here I can put in tomorrow. Sent from my SPH-L710 using Tapatalk 2

[MnTom]

I have a new Bosch one here I can put in tomorrow. Sent from my SPH-L710 using Tapatalk 2

Good. I don't believe that you have a timing problem from what you said. Symptoms of retarded timing are hard starting when cold, excessive white smoke (eye burning choking type) when cold, a steady miss until warm, not being able to raise the RPMs above 1500-1800. Once it warms up it will run good. Those are the symptoms that my truck had when the timing slipped.

[Rogan]

Swapped in the new one.. no change. Sent from my SPH-L710 using Tapatalk 2

[ISX]

The thing that gets me with all this is that 8mpg is dumping fuel... to the point that you might just look for a fuel leak. The lift pump might also be bad, that's why I said fuel pressure gauge rather than changing stuff yet. I just find 8mpg so far fetched without having smoke. If it's being dumped into the combustion chamber and seemingly burning it completely, you should be flying. The fact that it isn't and runs perfect, albeit with low power, is pretty odd. If it was leaking fuel and relieving pressure while it did it then that would explain everything. Might only be leaking under higher pressures or something, but I would definitely spend 5 min looking for anything soaked.

[Rogan]

The thing that gets me with all this is that 8mpg is dumping fuel... to the point that you might just look for a fuel leak. The lift pump might also be bad, that's why I said fuel pressure gauge rather than changing stuff yet. I just find 8mpg so far fetched without having smoke. If it's being dumped into the combustion chamber and seemingly burning it completely, you should be flying. The fact that it isn't and runs perfect, albeit with low power, is pretty odd. If it was leaking fuel and relieving pressure while it did it then that would explain everything. Might only be leaking under higher pressures or something, but I would definitely spend 5 min looking for anything soaked.

well, i had a overflow bolt. I DON'T have a bolt that will accept a fuel pressure gauge/tester.. I'll order a fuel pressure bolt tomorrow.. There's no fuel leak. Everything is dry, fuel-wise.. I don't see anywhere where that amount of fuel loss would be, and it would be noticeable. I agree 100% on the fuel/smoke thing, as well. The OE overflow valve spring had good tension and was right at 1/2" long.

[ISX]

I just calculated and if this mileage per say was at 2200RPM (guessing since you have 4.10's) and 55mph and 8mpg, vs. 18mpg....thats a 4 GALLON an hour difference.... That equates to 64 cups, meaning every minute you could take a cup of diesel and just dump it out the window.. Now you see why I don't get it. It's almost like one injector is just puking the fuel into the exhaust and not burning it and the exhaust heat is just vaporizing it. But then you have no miss... I mean to me it's like if everythingggggg was a little off canter, mayyybe it would accumulate to that kinda loss. But to have that and no symptoms other than a symptom that says it's not getting enough fuel... Definitely the truck of my dreams. A problem that doesn't make sense

[stodg73]

Do you have a locking fuel cap?????? The fuel may be disappearing this way.Is your oil getting thinner?? It could be leaking past the pump diaphragm/

[mr.mindless]

it really sounds like timing too far advanced to me. I wouldn't be surprised if you're at 6-8˚ static timing. Being an automatic, this is a 180hp pump without the timing notches, so high accelerator position won't retard timing. Therefore I don't think low fuel pressure alone could do this. I can tell you that while a P7100 will suck fuel, with a bum lift pump you'll be doing all you can to make 20-30mph up even small hills with a load. That was NOT a fun trip to southern DC.

[Rogan]

it really sounds like timing too far advanced to me. I wouldn't be surprised if you're at 6-8˚ static timing. Being an automatic, this is a 180hp pump without the timing notches, so high accelerator position won't retard timing. Therefore I don't think low fuel pressure alone could do this. I can tell you that while a P7100 will suck fuel, with a bum lift pump you'll be doing all you can to make 20-30mph up even small hills with a load. That was NOT a fun trip to southern DC.

here's the twist, mindless.. My 3500 was originally a 5speed truck, but the P.O. swapped it to an auto. So I have the 215. Update for you, ISX.. I'm at ~90miles on this tank, and just under 3/4 tank remains. That's WAY better than the last one, but it still is sitting around 11.5-12.5mpg. Sunday, I swapped the overflow bolt for a new one. I've seen no difference, at least with the power aspect. I also added a wire into the PCM's "C" plug for the OD sensor button and reconnected the OD wire as it should be. Prior to Sunday, I had the OD on a toggle, as well as the TCC on a toggle, so I could manually select either or both. Now, something weird happens (totally unrelated to fuel, by the way).. It will shift 1-2 @ 10mph, 2-3 at 25mph, 3-4 at ~32mph, then LU ~40mph. with the OD "OFF", it'll 1-2 @ 10, 2-3 @ 25, LU @ 30. If I continue accelerating, and turn the OD back on, it'll unlock the TC, shift to OD, then ~40mph, lock the TCC back. Strange creature, this truck.. Still seems down on power, as it did, and a lot of pedal effort & travel to carry above 50-55mph.

[mr.mindless]

Ah! Accelerator position certainly will make a difference, then. I'd been of the understanding that the 215 advanced timing about 2* at full acceleration, but what I read in ISX's post here contradicts that. In any case it at least makes checking fuel pressure more important. As long as you're not drawing it down to zero when accelerating you won't see any big symptoms. I did have a FP gauge when my lift pump died and the truck didn't fall on its face until I was at 0psi for several seconds. It was able to run all right on the fuel in the pump. I'd almost bet it could draw from the tank and run acceptably if it wasn't trying to draw through a failed LP.