Fuel pressure changed timing?

[Thewespaul]

I was thinking about this while I was on the road earlier today, and I bet the other few degrees of advance came from your injectors wearing in. As they wear, the pintle sits lower in the nozzle, which compresses the spring less, and with more mileage the springs loose tension, both these will decrease your pop pressure, which will result in the injector firing sooner, or more advanced. If you had checked the timing before adding the second pump I bet it would have been higher that where you set it previously and because it’s a slow process you don’t notice the timing slowly changing, until it was dramatized by the fuel pressure change.

 

[Garbage_Mechan]

Wes, I guess we think alike. I was going to ask that very same question. The injectors are Moose Mates that have 20,000 miles on them.

 

[Garbage_Mechan]

More findings:
Dash tach is off 200 rpm. Me: i“Hold rpm steady at 2000 so I can check timing” Son: OK. Me: I said 2000 not 1800 Son: yep got it dead on 2000. Sure enough off 200 rpm. Since it is a manual trans no effect on anything but the tach.

Fuel psi test gauge accuracy. I was using my nearly new name brand vac / pressure gauge. Never used it for anything else and never dropped it but noticed the needle not returning to center. Had 3 gauges in my pressure testing box in this range, they all were reading different on regulated air. Found I had a brand new liquid filled high quality 15 psi gauge. So went with it. Reading around 2 psi above the gauge I was using so now 9 to 10 lbs idle was yesterday’s actual reading. Vowed to get a good quality fuel psi gauge installed in the truck permanently.

 

[Garbage_Mechan]

So I have a Swagelok CPA-4 adjustable poppet valve set up as a pressure relief on the bleed line from the filter head to return to tank. I adjusted it down to have 6.5 psi fuel pressure with pumps on but engine off.
Here are the timing readings I got with my Mac ET18 DPM (same as SnapOn MT257) and SnapOn timing light:
At 650 rpm idle the timing was12*. Pressing the light load lever on the side of the pump all the way down without reving the engine brought the timing to 0*. At idle, applying power to the cold advance terminal increased timing to 14* a 2* increase. At 2000 rpm the timing is 8.5. I’m hoping Wes or Mel will comment on the timing change info.... does it indicate the pump timing mechanisms are working correctly?

 

[Thewespaul]

I’ve run into the same issues on replacement gauges on my test stand. Hard to find good quality even if you’re paying for it.

 

[Thewespaul]

That all sounds normal to me.

 

[Garbage_Mechan]

Road test: I have a 30 mile loop over to another ranch I do every 2 or 3 days to feed/ check cattle.
Found that the Swagelok valve has a little dead band to it, still within spec but not as perfectly steady as I hoped. Set at 6.5 it will occasionally hit 7 on the top. Under WOT it will drop to 4. (More on wot run in a moment) So not perfect but should not cause an issue.

 

[Garbage_Mechan]

My WOT (and hauling) test run is a 7% grade about 1.2 miles long straight up a canyon wall virtually no curves. Come off the bridge at 30, one curve then hammer down to the top.
When all this began (empty) you would get up to 5th about 1/2 way up and then loose it back to 4th. Crest the top at 50-55, throttle felt dead and truck felt like you were pushing it. Today I created the hill in 5th at 75. Still not much change from 1/2 throttle to full throttle, EGR 950 max no matter what, no visible smoke in bright daylight. Boost 7 psi max, tested wastegete actuator starts to open at 7 psi +- 2 psi. Don’t really want to push 200,000 mile 28 year old head gaskets any harder. It has always puzzled me why EGT never goes high on this truck maybe Banks location of pyro probe?

 

[The_Josh_Bear]

My WOT (and hauling) test run is a 7% grade about 1.2 miles long straight up a canyon wall virtually no curves. Come off the bridge at 30, one curve then hammer down to the top.
When all this began (empty) you would get up to 5th about 1/2 way up and then loose it back to 4th. Crest the top at 50-55, throttle felt dead and truck felt like you were pushing it. Today I created the hill in 5th at 75. Still not much change from 1/2 throttle to full throttle, EGR 950 max no matter what, no visible smoke in bright daylight. Boost 7 psi max, tested wastegete actuator starts to open at 7 psi +- 2 psi. Don’t really want to push 200,000 mile 28 year old head gaskets any harder. It has always puzzled me why EGT never goes high on this truck maybe Banks location of pyro probe?

If your pyro is after the turbo then that's plenty high EGTs, from what I've read 950 after turbo is about as high as you want sustained. Equivalent to 1150* before turbo. That's just the rule of thumb I've heard a few times.
Glad to hear the improvement!

 

[Blue94]

You probably weren’t getting enough transfer pressure with the previous fuel system to overcome the light load advance piston spring, which is why you are seeing so much more advance with more inlet pressure. I would set the timing at 9* now, or play with it and see what makes the best compromise between top end power and economy. Your injection pump is fine, I’m sure you’ve read the other threads were the facet owners are having delivery issues and dropping fuel pressure under load, I was just commenting on how it’s surprising to see it still drop fuel pressure under load with two facet, just further says to me they are really under sized for our application. 66 gph is free flow, I preach the mr gasket 105p pumps a lot, they free flow over 100 gph.

Where do you mount the 105P, frame rail as a pusher or inner fender as a puller?

 

[Thewespaul]

Where do you mount the 105P, frame rail as a pusher or inner fender as a puller?

On the frame rail, same with the holley pumps, they are designed to be a pusher.

 

[Blue94]

I haven’t checked it but I know I am having fuel issues with my facet and my timing is a bit off anyway. Dad has loaned me his snap on inductive injection line tool (snap on) but I need to fix the fueling issue first. I am sure that facet drops to 1 psi under a load. I may be hitting you up when I do that to pic you brain.