no start, no fuel at injectors, super short GP cycle

[neo]

Any guidance or suggestions are greatly appreciated.
96 K2500 burb 6.5 TD and 4L80e trans. Not much, but ,little mods, remote PMD, larger downpipe, cat free, Tubomaster, etc. New injectors about two years ago at 175k or so, ticker currently has 208k. New timing chain set past Christmas.
This morning, after sitting for a couple days, she would not start. Cranks fine, just won't start.
Cracked injector, no fuel. Replaced lift pump today. Checked Fuel Shut off solenoid, operating as should, Normally closed and opens on 12V.
Here is the weirdest (to me) part. THe GP and lift-pump cycle is SUPER short, not even one full second. I have an auxiliary GP switch/solenoid and can run them till my finger wears out, still no luck. I hear the new lift-pump cycle for a half second or so and then that is it. I opened the relief/bleed on the top of the filter and it still only runs for a flash of a second. I have disconnected battery to the system for about 20 seconds hoping to reset, still super short cycle. I have checked for codes, there was a turbocharger pressure code (237) that I cleared, but that has probably been on for a long time.
When I pulled the Fuel Shut off solenoid, no fuel actually poured out. Is it possible I am clogged back at the tank? Could I be out of fuel and not realize it, ie not indicated on the gauge? I will check that next, but if you have anything else I should check?
I think the super short glow cycle is what has me most confused.
Thanks!

[greatwhite]

That's a touch puzzling.

If it were an OBDI I would have suggested the oil pressure switch, but the OBDII trucks run the lift pump on the PCM with the Oil pressure switch as a "legacy" circuit.

Even if the lift pump is toast, the IP should be able to pull enough fuel to run.

It sounds like the PCM is shutting stuff down on you.

Why I can only guess.

First suggestion would be to make sure you have a good clean ground at the rear RH intake bolt. This is the grounding point for the ECM and will give all kinds of weird issues if the resistance (IE: corrosion) is too high. It's a quick and inexpensive (IE: free) thing to check.

The other thing that comes to mind is the ignition switch. Not the key cylinder but the electrical switch down on the column. You would be surprised what runs through there and they do wear out after years of use.

These are all just shots in the dark, kinda need to put "hands on" with this kind of issue.

Over the net is darned near impossible.....

[neo]

ReAlly appreciate the fast reply and great suggestions. I checked fuel level and all is good. I will break loose the fitting after the pump and make certain it is at least pumping while it has a signal. I hear it run for half a second or so. Ill check the ground this evening.
It seems there is an issue with either an input to the computer or the computer itself. The super short gp/lp cycle is what i am finding so strange. I like the ground issue and will check it first.

[neo]

So, I found the grounds, they looked good, but I went ahead and cleaned both of them up and replaced the eye-lug on both just to make 100% certain after initially just cleaning them and mashing them down a little to attempt good contact. Still no luck. The engine is cold, has not run in a couple days, and the gp/lp continues to only click on for a fraction of a second right as I initially turn the ignition on. It never repeats the cycle like it should. They come on for a flash, and then off.
Definitely no fuel at the injectors. Tested that again to be certain I was not dreaming. Engine cranks great. I would suspect the IP cause it probably has 125k on it, but the glow plug/lift plug part has me fooled.
Is it possible the IP is sending a signal to the computer that it is running and does not need the gp? Why when I crank it and open up the fuel filter vent is there no fuel coming out? That tells me the LP is not running when the engine is cranking, that seems odd too.
Another oddity, or at least I think it is, my Auto X-ray scanner says the engine temp and the inlet air temp (both read the same?) are between 275f and 303F. I unplugged (on the pass side of the cross over) what I think is the temp sendor and the scan tool readout went to 303 and stayed, where before it was jumping around a little. COuld this mean: 1. sensor issue telling computer not to run gp/lp - but shouldn't the lp run? or 2. the computer it toasted (lightening? - we did have a fierce storm yesterday roll through) and just simply FUBAR. THanks for the help folks. I am honestly stumped and at wits end
Neo

[greatwhite]

No fuel at the air vent indicates either the line is plugged or the lift pump is not running.

If your up for it, i would suggest you crawl under the truck and crack the fuel line where if feeds the lift pump. Take a bowl or jar and see if you can get a cup or two of fuel to drain out. If it does, you can be relatively sure the line isn't clogged from the lift pump to the tank.

It will also give you a chance to examine the fuel clarity coming from the tank. Glass mason jar and Monsieur Soleil works great for checking the fuel. Water will be little shiny spots or globs, dirt is...well, you'll know it when you see it.

Then i would jump 12v to the lift pump and see if it pumps fuel to the filter manager air bleed or the water drain.

If all that is good, you're up to the fuel shutoff on the pump. You say this is good, so we move on.

At this point it's a bit of a toss up between electonic bits.

It could be the pmd not working, or it could be the fuel solemoid not working, or it could be the pcm itself. Or (gid forbid) some kind of mechanical failure in the pump (unlikely).

It is not surprising that your glow cycle is short if the pcm is showing 275 f. It reduces glow time in the program as determined by ect.


I would suggest you unplug the ECT and see if your glow cycle/lift pump issue changes. What happens when the pcm isn't getting an ect signal is it thinks it's full cold and runs a standard cycle with cold enrichment fuel.

If this fixes the glow cycle i would say you either have a bad sensor, shorted wiring or a pooched PCM. If the ect is still up around 275 after disconnecting the ect sensor, I would suspect you have a wiring or pcm problem.

The iat is a bit puzzling if it matches the ect. Maybe trace out the wiring bundle to see if you have chaffed or broken wires somewhere.

It is entirely possible this sensor issue is the route of your problems. Goes something like this: high ect reading cuts back the glow/lift pump run time. Its been a while since i looked at the gp tables in the cal file, but I'm sure i remember some .5 second glow time cells higher in the temp range. At 275-303 you are definitely at the top of the table.

Low run time on the lift pump prevents the filter bowl from filling properly. Then it gets some air in the system which fires off the ip op sensor codes. You get a big slug of air in there and the ip looses prime. Now you don't have prime in the ip so it cant even pull fuel from the tank. So, you're now dead in the water and don't know why.

Yeah, the more I think about it, the more i think i would disconnect the ect sensor and see what happens. Or, 12v prime the system by powering the lift pump directly (temporary hook up of course)...

[More Power]

Another oddity, or at least I think it is, my Auto X-ray scanner says the engine temp and the inlet air temp (both read the same?) are between 275f and 303F. I unplugged (on the pass side of the cross over) what I think is the temp sendor and the scan tool readout went to 303 and stayed, where before it was jumping around a little. COuld this mean: 1. sensor issue telling computer not to run gp/lp - but shouldn't the lp run? or 2. the computer it toasted (lightening? - we did have a fierce storm yesterday roll through) and just simply FUBAR. THanks for the help folks. I am honestly stumped and at wits end
Neo

Unplugging the electrical connector from the ECT (engine coolant temperature) sensor should produce a -40F reading using a scan tool.

I've not heard of a lightning storm damaging a vehicle electrical system or PCM, but I suppose it's possible. If you see other unexpected info using a scan tool, the PCM may have been damaged... Jim

[greatwhite]

Ah, I missed the "you already unplugged it part".

I would suspect a wiring issue (chaffing, grounding, etc) or possibly a PCM problem.

Jim is right, it should show full cold when unplugged. That's why I suggested it to force a full GP cycle.

Also, as Jim mentioned, a lightning strike frying the PCM is possible but it would be the first one I've ever seen in 32 odd years of working on vehicles.

More likely if it is a PCM fault is just happened to calve around the same time your storm rolled through. Coincidence can be a "female dog" sometimes....

[neo]

Thanks guys. I am on the verge of replacing the Ds4 with another one and testing it or replacing it with a db2 and being done with the electronic nightmares. The symptoms have changed a little this morning and evening, and I found an interesting find, but it did not resolve the problem.
First off, now my glows and lift pump are cycling the way they should. This started this morning. Still no fuel and no start though.

As I pondered it all day, I decided to check my PMD extension cable. It was purchased from DC some time back and I have had trouble with it in the past - wires burnt off inside the connector. As I ohmed out the wires, I found (when looking at the female end that plugs into my harness) the fourth pin over from the left, third from the right did not have continuity. Pulled the plug (female at the harness and found that wire burned off. I pulled the pin out, cleaned everything and soldered it back. Checked it for continuity afterwards and all was good. STILL no fuel.
The lift pump is definitely doing its thing. Loads pump up through the vent at the top. all good there. No fuel to the injectors still though.
Looked the temps with the scanner and it is still pretty screwy. Still shows 303 and 300. If I unplug the sensor on top of pass side of coolant cross over, it does not change, just stays at 303 but the short cycle starts then. Really weird.
Still not fuel/fire.
So, I tried both PMD's and still nothing. If the pump has pulled enough current through the wires in the extension harness, is it possible the pump is bad? Could it have killed the PMD too? Why would it burn the wire? Is it that much current? DC probably made these out of like 18 ga wires, so they are fairly thin. Power consumed is a function of the square of the current and resistance IIRC, so could it be something inside the pump causing the issue?
So, next, is it best to trash the DS4 and bite the bullet and go with the aftermarket controller and use the DB2 and kiss it all goodbye? Or will places the AZ and Advance let me take the computer, put it is and try it? Why are my temps showing so high? This is driving me insane. Thank you all for the help. I have to use this truck in two weeks to travel and really starting to get desperate. Thanks!
Neo

[greatwhite]

Curious question: have youchecked your manual gp circuit?

I know some types try to spoof the pcm in to thinking it's colder than it is with a resistor.

Could be the source of the odd temp readings.

Pull your shutoff solenoid agian and verify you have fuel that point and the shutoff still works.

Your pmd extention harness and description would make me suspicious of that as a failure point. But if it's been metered for continuity it should be good.

Which brings me back to (with no fault codes present) pmd, fuel solenoid (delivery, not shut off), wiring or pcm....

[neo]

Thanks again for the great input, from everyone. THis dialoge is one of those thinks I always think abotu when I keep up my membership. I love this site!

I forgot to mention, it keeps tossing a P0004 code, which is somehting abotu fuel pressure regulator. I don't remember more than that and it did not make much sense to me.

I agree wholeheartedly abotu your synopsis. At this point, i intend on checking continuity on the cable once again. IF good, and I bet is it cause I did plug a spare module directly into the harness just for tesiting, it almost has to be the pump, wirng or the PCM. At this point, I am thinking DB2, TCI controller and NEVER have to think abotu this crazienss again.

THanks again to all.
NEO

[john8662]

DB2, naw...

those parts are hard to find. The Throttle cable and petal are discontinued and not available. Cruise cable same deal...

You have a wiring fault.

Shoot, there is a 1996 wiring harness on ebay that you could throw at it way cheaper than converting to DB2.

To me it seems like a broken ground somewhere IN the harness.

An alldata DIY membership will grant you access to all the wiring diagrams for a 1996 Burb, then you could test for continuity on all the wires and pins. It'll take awhile, I know, did the engine test stand thing with a DS4 OBD-I, they're simple. I'd still like to do a OBD-II on just to say I've done it...

At least with your 1996 it's not a theft-deterrent issue like it could be on a 1997+.

J

[phantom309]

If you make the switch to manual,. you could look for the 93 only, manual pumped 6.5 setup, with the trans computer that runs off a tps on the pump,.,. waay cheaper than tci stuff,.

nick

[neo]

Finally figured it out. It is the PMD! AGAIN!!! ARGH! I HATE THESE THINGS! Can't believe this again. Borrowed a PMD and she started right up (after I fixed the extension cable for the relo kit. WTF?? Are these stupid things only supposed to last for a year or so before they crap out again?
This alone makes me want to scrap the DS4 and do the conversion to the DB2.
I cannot believe I am going to shell out another $200 for another PMD. It is like a "fee" to drive the truck. I have been through both Stanadyne replacements and Dipaco(sp) replacements.
Is there a better one out there? Is it possible to get more than a couple years? I have mine mounted under the front bumper on a massive heat sink with thermally conductive paste. I HATE THE PMD!
OK, I feel a little better now. Thanks to all who chimed in.
On another note, I have found all the parts needed to get rid of the DS4 forever. I read the full conversion manual, where you use a box truck TCU or something like that. That all looks good, but there is no programmability and it looks like there is some time in re-wiring a few things. I think I am going to go ahead and *splurge* for the TCI. I have the TPS, throttle cable, hard-lines and I believe that is about it.
More to come.
Yes, I figure I will lose my cruise, but no cruise and no PMD are a good combo for me. That OR... someone can come pick this thing up out of my front yard once I burn it to the ground.

[greatwhite]

Not sure what to tell ya there.

I'm running a PMD kit from Bill Heath.

3 years now and no failures related to the PMD. Before that I was using the one that came with the truck for at least 2 years (it was an old OEM style stanadyne black) on a tiny heatsink that looked like it was a t least a couple years old.

I did have a bit of water intrusion somehow on the Heath one and it caused some "green fuzz" corrosion on the resistor card. This bridged the resistor and made the PCM think it wasn't there at all. Quick shot with contact cleaner and a little wipe and all was good again. Packed the connector with Grote grease and no further problems.

It's a Dtech PMD on his big aluminum sink with his extension harness. 7 year warranty but I paid 500 bucks for it at the time.

of course, there's lots else to go wrong. I've also replaced a fuel shut off solenoid and an Optical sensor (that was fun, not) on my DS4.

You don't have to give up cruise if you go DB2, just grab a cable cruise off a gasser plus associated wiring and it will adapt right up with a bit of fab work for brackets and such. Your VSSB already puts out the speed signal it's looking for.

[Warren96]

I would check for loose connections on the extension cable.The cable extender that i use is homemade about 3 1/2' long with only 22 AWG wire.If I had repaired my cable twice already like you have, i would be considering a new cable not a mechanical pump.Call some of the advertisors on this site and see what they get for one, I'm sure it's a LOT less than changing to a mechanical pump.Using a silicone based lubricant on electrical connections will help ease corrosion, but not loose connections.