The '94 has not been right since water in the fuel two weeks ago.
It will run, but goes through faults restarting hot.
I had the scanner on this morning and whatched the progression.
It gave DTC's 18, 36 and 54, which correspond to the optical not reading.
Truck will always stall when it faults.
I cleared the codes and restarted it and it fired up without a problem or codes.
This has been the pattern.
The current timing is 4.7 desired 8.0 actual. This is my optimal setting as far as I can tell.
I replaced the injectors and at least one was bad.
I have secured alot of weak connections looking for problems
Any insight that could be shed on this subject is appriecated.
Edited by: quantum mechanic

Unplug Optical Sensor, start, run for 15mins


Stop, re-connect OS, restart, check data

just did it.
Started right back up showing 4.8 desired, 7.2-8.0 actual (moving progression).
It has been starting much better since this morning. I've probably put 80 or more hours into this truck this week.

36 could also mean the Fuel Solenoid is dragging\sticking.


Not familiar with 54.


Have you checked the fuel inlet screen, and the Fuel Shutoff Solenoid area for 'things' in the fuel?


Do you have a spare DS-4 inj pump?


And, you never did post what color label your pump(s) are.

This is a green tag DS pump.
I've cleaned/inspected the fuel inlet, return inlet and optical low res with denatured alcohol.
I also put a wrench on all the injector lines and gave them a jolt to seat them.
I don't have a spare DS-4.
Called the stealership for laughs it was $1645 new or so he claimed.
Found an optical for $322 in Houston.
I am starting it with the scantool each time for a visual on the sensor.
The fuel pump angle readout, desried and actual timing give erratic signals when it hiccups.
54 TIO fault
I would guess timing indicator output.
Edited by: quantum mechanic

how do the pins look on the plug-in wire going to your optics? bad contact maybe? I'm gonna guess that the sensor is bad. You did put that vent wire back in right? Torqued the sensor back down too?Edited by: Texas Diesel Guy

I restarted it and it did the same faults.
unplugged the optical, started it.
plugged it back in restarted it optical reading but the advance is making the idle surge.
But after reading your other post i thought about how the cap always releases alot of vacuum from my tank when I fill up.Edited by: quantum mechanic

When you removed the fuel inlet fitting, or transfer pressure regulator as we like to call it, did you notice any signs of damage to the lower red o-ring? any leakage there will dump transfer pressure back into the inlet and cause a lot of strange operational problems.

Fuel inlet, I removed the threaded nipple w/ oring, then the allen screw with a tiny hole in it.
everything looked operational.

PM me a convenient place to meet tomorrow AM, and I'll ease out and donate the Blue Label Green Tag 5288 inj pump I just pulled from my engine.


Bought engine Spring '99, a Goodwrench engine with dated assys from Sept to Dec '95.


Pump is Sept 95, lost first PMD Summer '01, second going strong thru June '04 on that pump, now on my replacement. Other than that, not even a hiccup from the pump.


Donor truck had 129000mi - I would suspect this of having around 60kmi or less on it.


Replaced it while into the eng for half-crank-speed rapping sound, similar to collapsed lifter - turned out to be flex plate broke full circle at crank hub.


Also got my original EGT gage, from a Peterbuilt, you can have. You should be able to pick up a Type-K probe for it .

wait wait wait! you removed the viscosity compensating orfice plate from the transfer pump reguator assy?????? that screw has a spring and regulating piston under it to set transfer pressure, has to be set to get desired transfer pump pressure at specific fuel delivery/temp/speed on a test stand, how far did you screw it back down????

About as far as I unscrewed it.
It was snug against the spring but not torqued.
I drove the truck 70 miles today without incident.
It's only when I turn it off that it's a problem.

Are sucking air somewhere here? Only screws up on startup after sitting? Like air leak maybe around the fuel filter housing, and getting a bubble into the IP and causing problem with optical. Any takers, or just a wild shot?

Leaks around the filter housing was causing problems earlier in the week.
I removed the lower intake and inspected all the lines and fittings, fixed some.
I'm positive no fuel is leaking now.
I am going to try another optical and see haw it does.

Today I started it a few times and whated the sensors noting that the signal was more erratic than nonexistant like when it's unplugged.
Gmctd came through and I received his old pump this morning.
I was feeling pretty confident that just the optical was bad.
I switched the optical from the old pump to mine and it fired right up with timing reading aok.
I am going to restart it a few more times but I'm thinking it's fixed.
Thanks guys! Gmctd, I would like to thank you sir.

Check the wiring on your sensor - could be all the recent 'manipulations' have resulted in intermittent continuity, module to connector.


Might be salvageble, with a little tlc.....


Get your analog EGT monitor installed - it's the best gage of performance results.Edited by: gmctd

QM, your 'new' sensor is late style 33883?

GMCTD,
I tried pushing the wires in on the connector and harness.
I think that it was fried. The sensor off your pump fired the engine right up, the old/bad one took a bit of cranking before the engine would reach ignition.
It starts like it should now,one second of crank and it fires, everytime so far, how could I complain.


TDG,
How would I verify that? The number on top says:32586
Also, I had a non vented cap, so did my dad.
I drilled a hole through the back near the handhold and they vent now.
Edited by: quantum mechanic

Quantum Mechanic, my fuel cap lets out a whoosh when I take it off to fuel. Is this a bad thing? Should I not have pressure in the tank? I'm confused, could someone shed a little light? thanks Oh ya, 97 cc dually 4wd auto and 6.5td

LargeStar: What your hearing is vacuum not pressure.


QM: The number is 32865 and thats a 2nd gen.

Largestar - the Diesel fuel cap has a dual function valve - relieves vacuum in cold weather, pressure in warm weather.


Vacuum is not good - makes the lift pump work harder.


Vacuum can also collapse the fuel tank, if un-vented.


Valve is set to vent at 2"wc, iirc


Pressure is good - eases the load on the lift pump, prevents drain-back


Higher pressure can blow fuel out tank when cap is opened.


Valve is set to vent at 1psi, iirc.


Large volume of fuel tank can make 1psi appear to be much higher pressure - just multiply 1psi by L x W x H of tank (area in cubic inches) to get a sense of volume of pressure escaping when removing the cap.


More volume from an empty tank than a full tank - can appear to be much higher pressure.


Fuel caps are exposed to varying climate and environmental conditions, causing either or both valves to become non-functional.


Can be checked with an automotive vacuum tester, and pressure tester, small hand pumps available at most parts houses.


Or, simply replace it with a new, lockable cap for Diesel service.Edited by: gmctd

Since we are on the topic of fuel caps, here's one for ya: Maybe TDG can answer this one.


I had IP problems when I got my van. Found first, that the lift pump was bad. Changed that. No real change it seemed, because IP had problems (optical and meter control codes) But, here is the interesting thing: I could drive about 6 miles, and begin to lose power. So much so, that the I could not maintain 60 mph. It would slowly drop off. I pulled into a gas station, and gave the fuel cap a twist, and HHUUSSH. Broke the vacuum. Now I could maintain any speed, for as long as I wanted. Seems simple right? BUT, I had mounted a fuel pressure gauge to mointor the fuel pressure coming into the IP, AND IT NEVER DROPPED.


So, what gives. Fuel pressure to the IP never dropped off, so therefore, in my mind, the fuel volume should still be available. So, what would cause the power to drop off? Any thoughts?

Would be easier to explain if that were pressure.


Tank pressure greater than 1psi can cause fuel return problems, where inj pump housing pressure cannot be regulated.


Causes timing and inj problems, and increased internal fuel temps, which can result in PCM pulling fuel - less power.


This condition would result in stable lift pump supply pressures.


Tank pressure can 'blow' cap loose, 'hiss' is somewhat longer duration, as tank volume is venting into Baro.


Excess tank vacuum indication is some difficulty in unscrewing fuel cap, hiss is short, as Baro equalizes in tank.


Causes vacuum-lock at lift pump, low-to-no supply pressure.


Good idea to maintain fully functional fuel cap(s).Edited by: gmctd

Texas Diesel Guy,


"wait wait wait! you removed the viscosity compensating orfice plate from the transfer pump reguator assy?????? that screw has a spring and regulating piston under it to set transfer pressure, has to be set to get desired transfer pump pressure at specific fuel delivery/temp/speed on a test stand, how far did you screw it back down????"





Are you talking about the fuel inlet of the IP ?





I had that fitting off once and blew air into the opening trying to dislodge any junk that might have been there. I didn't see anything like you guys are describing. I was worried at the time that I might have blown some small parts into hyperspace.

the fuel inlet is threaded into the transfer pressure regulator, inside is the viscosity compensating orfice plate, which is threaded against a spring and regulator piston to control transfer pressure inside the pump. if you just blew air into it and didn't unscrew the plug inside, then you have nothing to worry about. if you removed just the fitting then you might have noticed the 5/32 allen plug underneath, which is the orfice plate and Trans press adjusting screw.

Found an optical for $322 in Houston.



You can buy just a optical sensor? $322 for a stupid little optic sensor? I am in the wrong business. All it is is a LED and a photodetector with a lens in epoxy! If anyone knows where I can get a use, broken, whatever shape optical sensor. Dirt cheap! (Just need a dead one) let me know! My business deals with more of these type of sensors than Stanadyne.(Not for diesel fuel pumps particularly though but we have worked with fuel oil submersed sensors) I'm sure the epoxy that they used (Inferior type)cracks from the fuel (Been there) causing the lens to move when heated or other. Mount the actual detector external and run fiber optic to the sensor ring. Mount the entire mess external. This is my second project.


QM, You hit the nail on the head when you said "Stealership"

I just removed the fitting, I didn't notice the allen screw that you mentioned but I was doing this with everything else in place. It was hard to see down in there.





Thanks for the reply.

Bob, its in there, trust me.


MDH, Stanadyne went through 3 sensors before they got it right, at first they had just the problem you mentioned epoxy and plastic would crack, they've fixed that problem and the 3rd gen is very reliable.

My 5066 green tag pump started a new problem. It races so to speak. I went ahead and put the 5288 that gmctd donated on in it's original configuration. The new pump seems to have about 50 less horse power in it. I advanced the optical with different results than I got on my old pump. I couldn't advance the sensor too much. That is to say that with the optical sensor pushed fully to the passengerside it runs best, but it never reached a point where it jumped at idle. Also the new pump seems to have cured my "surge" at highway speeds. The TCC doesn't disengage anymore at less than 15% pedal while going 60-75 mph. It would seem these problems went with the old pump even though the APP still reads it's typical values(my APP has been bad for 9 months at least).


Did my "adjusting" of the internal pressure valve do me in?

It seems the fuel solenoid is dragging on the donated pump. It's getting me around right now but I see a replacement in the near future.