95 PSD Power Loss Questions

[dsrace]

yes there is an electric pump on my '95 psd, mounted to my frame rail, drivers side just before the tank. you can't miss it with all the fuel lines coming in and out of it. w/ intake and exhaust, his auto meter gauge (tapped into the intake not t'd off the hose) read 27 lbs , I'm pretty sure that was before the tune but that was some time ago, I'll check. aren't the stock inj's 90 cc? I know with stock inj's, w/ intake and exhaust, in an 80 hp tow tune I see 22lbs wot in 3rd (auto).

saw this in another post, thought it might help "It should be higher than 50 at idle and 30 - 90 at WOT."

 

[dsrace]

it is not a pump but a selector for the dual tanks on the frame rail and he said 25 lbs before the tune at wot.

 

[94f450sd]

it is not a pump but a selector for the dual tanks on the frame rail and he said 25 lbs before the tune at wot.

the max boost a psd will make with stock tunes and any injectors is around 18 psi

 

[RJMorrow]

As a follow up I used a Snap-On scanner to run diagnostics. I found that injector buzz test and cylinder contribution passed. Only codes retrieved were P0476 which I understand is probably due to clogged line to exhaust manifold. I did observe exhaust back pressure at 32psi at idle and as much as 42 under light load. I also did note engine appears to miss at high rpms.

 

[94f450sd]

clean or replace the tube coming off the passengers side exhaust manifold or if you can find it get the exhaust back pressure sensor dongle.i havent seen them in a long time though.

 

[dsrace]

the max boost a psd will make with stock tunes and any injectors is around 18 psi

so then his auto meter gauge is off by 7psi, believe what you want but seeing is believing.

 

[RJMorrow]

'95 PSD Power Loss Problem

And exactly how does your arguing over 7 psi of boost actually help me to get my truck running correctly?

 

[G. Mann]

Does your 95 have a catalytic converter? My 97 did, so that is the basis of my question and possible answer to your problem.

If the cat is degraded it can cause the exhaust to be blocked and choke power kind of like you describe. Everything else on the engine can check out fine but it just can't pull power. Kind of like the old potato in the tail pipe trick.

At idle or low speed enough exhaust passes that it runs kinda OK but at high power under load it reaches a point where it won't do any more.

If you don't have a cat in the system and the muffler is ok then "never mind"...

 

[RJMorrow]

Thanks for the reply. Without admiting to any lawbreaking I can tell you there is no cat on the truck. The stock muffler was replaced with an aero turbine about 5 years ago. It is my understanding that due to their no baffle design, they wont plug up.

 

[G. Mann]

Ok then... that possibility is eliminated. On to next one.

Throttle position sensor? I forget... PSD electronics isn't my strong suit. Also, have you done an "upper oil change".... the PSD injectors capture an oil supply that "hangs" in the what-cha-ma-callit [high pressure oil pump thing] and gets gummy. Makes the injectors act badly.... may be worth a look. Somewhere I saw a U-tube by a guy that's a PSD guru about how to do an "upper oil change" on PSD. Google maybe?

 

[94f450sd]

so then his auto meter gauge is off by 7psi, believe what you want but seeing is believing.

yes.not what i want to believe.its what i know from messing with the psd for 6 years and dumped untold amounts of money on one to get a 7,000LB crew cab dually down the 1/4 in 15 seconds.

 

[OLDBULL8]

the PSD injectors capture an oil supply that "hangs" in the what-cha-ma-callit [high pressure oil pump thing] and gets gummy. Makes the injectors act badly.... may be worth a look. Somewhere I saw a U-tube by a guy that's a PSD guru about how to do an "upper oil change" on PSD. Google maybe

That's a bunch of BS. The HPOP reservoir oil is being changed constantly, as long as your running. The LPOP supplies it from the oil pan. The oil from the HPOP to Injectors returns to the oil pan, not the HPOP reservoir. To begin with there is less than a quart in the HPOP reservoir. There is no easy way to drain the HPO rails, they contain very little oil volumn.

 

[G. Mann]

The oil from the HPOP to Injectors returns to the oil pan, not the HPOP reservoir. To begin with there is less than a quart in the HPOP reservoir. There is no easy way to drain the HPO rails, they contain very little oil volumn.

******

The point you make is the point that I made. Apparently, the oil does NOT return to the pan as you think, but remains in the HPOP resevoir until it becomes sludge. The UTube procedure I saw specifically addresses that issue and how to suck the resoviour out and refill it with fresh oil to restore injector function. Rather than screaming BS, have a look at it as a potential problem with PSD's design. Since the PSD injectors open and close on high pressure oil, they are quite sensitive to oil condition and/or HP pump pressure. I'm simply pointing out that issue and that it may apply to the problem presented by OP.

 

[94f450sd]

The point you make is the point that I made. Apparently, the oil does NOT return to the pan as you think, but remains in the HPOP resevoir until it becomes sludge. The UTube procedure I saw specifically addresses that issue and how to suck the resoviour out and refill it with fresh oil to restore injector function. Rather than screaming BS, have a look at it as a potential problem with PSD's design. Since the PSD injectors open and close on high pressure oil, they are quite sensitive to oil condition and/or HP pump pressure. I'm simply pointing out that issue and that it may apply to the problem presented by OP.

there is no need to mess with changing the HPOP oil.the HPO system works just as oldbull stated.the injectors dump the oil through a spout into the valve train and then it drains back to the pan.

 

[94f450sd]

have you even put a scanner on this truck yet?if not you should,watch all the read outs and see what the oil pressures are doing.also run a buzz and cylinder contribution test on it.