Stalling, been using biodiesel

[jdmetcalf57]

1999 K3500 about 70K on FSD. I am going thru the list for stalling but would appreciate anyones input. My truck has stumbled a few times and a couple of times died. Today it died and would not restart for 15min. It does not give me any trouble codes like the last time I had to replace the FSD. Do these FSD's often quit without throwing codes. I do have a permanent pressure gage plumbed into the fuel line just before the injection pump so I know pressure to the pump is not a problem. Would anyone reccommend where to buy a new FSD. I want to remote mount it on an old large stereo amplifier heat sink.

I have been using straight homebrewed biodiesel for about a year (at todays prices about $2400 in savings) I try to be very careful about making it and it is filtered thru 7 filters before it is used in the engine. 2 of those are 2 micron rated water seperating filters. Does anyone know whether you could take the top of the pump off and get an idea if water has been a problem? I am leaving on a 3 week vacation to the mountains in 3 weeks. Was planning on taking 150 gal of bio with me.

[Robyn]

What you are describing sounds like a classic PMD gone south.

Install a new DTECH PMD on the remote cooler and things should be fine.

best

Robyn

[kf6zvt]

Got a '94 6.5TD (208K on the clock), just went through the stalling routine.:confused: Replaced the PMD with a Dtech model, very happy with what seems to be a slight gain in performance. Not so happy with the fact that it stalled again.:mad:

Checked tank, fuel pick-up, fuel pump, ignition switch, all grounds, fuel lines. When the engine would stall there was no code set and no SES light. All electronic components would continue to function as normal, leading me to believe it was a fuel rather than electrical issue.

Finally found some posts that indicated the Oil Pressure Sensor might be suspect. Too bad I found it late, the OPS is like 10% of the cost of a PMD. And it fixed the problem, again with some minor improvement in performance.:)

I found out the OPS has two circuits in it, one for the fuel pump and a second for the oil pressure guage. So falling or low oil pressure will not be indicated even if the OPS is at fault. And there is not a connection from it to the PCM to set a diagnostic code.:eek:

Now it runs a lot like it did years ago. The OPS is not fun to change but with a KD Tool # 3458 and about 18" of socket extensions you can get to it from the passenger side. I tried 3 different "OPS sockets" before I found the KD, all others either fit very poorly or put too much side pressure on the plastic sensor body. Even the KD tool got bound up on the removal and broke the plastic off the old sensor.

[arveetek]

I've been running home-brewed biodiesel for about 2 years in my '95 6.5L with no problems whatsoever. I have had the PMD fail twice in that time frame, though, as well as the OPS. These are not fuel-related problems, though.

I'm currently running the Dtech FSD and Kennedy's OPS harness.

Casey

[94burb]

I had that stalling problem as well on my 94 that didn't go away with a new DTech PMD. Check the optical sensor encoder on the top of the pump. That was my stalling gremlin. Swapped it out and it is running pretty good ever since.

[JoeX87000031]

Burb,

If you have the time, could you explain what this optical sensor on your 94 does? Take care