Diesel problems with good pumpe

[DonovanNorway]

hi

Here is some history of the problem: Because of an accident the pickup has sat for 2 years, it ran good when I drove it into the barn. 1998 3500 manual silverado.

After putting it back together the pump would not pump to the injectors, I checked that fuel was comming to the pump. The lift pump pumps about 30 seconds when i turn the ignition on. I took the fuel line off the pump and it fills a pop bottle in about 15 seconds. Fuel also comes out the return line when turning over the motor. My first thought was shut off solenoid, it clicked as it should so i moved on to the FSD, I borrowed the FSD from my sub and this did not help. I was then thinking that maybe something in the pumpe was frozen. I send the pump in to have it tested on a bench and it worked fine!

I then put the pump back into the pickup and thought that maybe it was air lock problems, loosened all lines from injector exsept for 2 under turbo, this did not help. I then loosened the lines from pump and notice that the pumps sprays diesel the first round that it goes and then stops.

I have checked what type of volts i get with key on and everything seems to be perfect with what I get out of the book. FSD gets 12V, and 5V, and has ground nothing on fourth wire. Optical Sensor get ground on 2 and rest is 5V. I then to make sure that the wires are ok checked the continuty between each end, evverything ok.

I have ruled out the oil pressure relay since the lift pump pumpes when ignition is turned on and when i try starting. (is this correct?)

One thing I noticed is that when I took the fuel line off the pump to check if the lift pump worked while starting was that when turning over the motor diesel the would spray up in spurts, out of the the "fuel in" on top. Not sure if this is normal.

The motor will now fire sometimes but only once at most each time i try to start.

I'm out of ideas, any suggestions?

Donovan in Norway

[DonovanNorway]

not getting much help in here!!!! I have tried more things now and have more information. I attached a 5v light on the back of the pump between all the injector lines and it will only blick 3 times and then no more, until I shut off the ignition and try again... three blicks. I changed the oil pressure sensor that did not help, I then tested the crankshaft sensor as described in Haynes book and everything seems normal.

I then took the steering wheel column from my parts suburban (worked 2 weeks ago) to check if the problem could be in the ignition, this did not help either. Went over all the connections again opened them checked for corrosion and put together again. Also tried other FSD today but still no luck!

I ordered the Allinone OBDII cable for pc today as well but will take 5 days to get here. I would really apprciate any help or suggestions you might have. This 6.5l is really kicking my butt!

[Warren96]

Can you check to see if is setting any codes?That is were i would start.

[gmctd]

Agree - pull any DTC's and post them here.

[Hubert]

2 yrs sitting could injectors have gummed up, stuck, or not spraying- atomizing fuel? You have fuel to IP, IP checks out ok on bench, its spinning fast enough, and the cylinders are warm enough - it should fire somewhat. So why is it not injecting fuel correctly? Crossed or mixed up fuel line ( I have heard of that). Lost some ECM settings??? Have you tried to unplug the optic sensor and force it into limp mode? Or could be injector lines/IP severly air locked? Try unloosening lines at injectors one at a time and crank until good and wet tighten line back up. Repeat for each injector or until it starts. Set up a battery charger and let starter cool between cranks but take your time and purge each line a good while. Add a heavy dose of cetane booster and fuel cleaner to fuel. You could plug in block heater and let it get good and warm and unhook glow plugs and spray a little WD-40 into air intake to see if it will fire after you purge the 1st or 2nd injector line. But if you do this verify the injector lines are installed correctly first.

I don't know what a fuel pressure does at the IP inlet but notice my fuel pressure gauges needle bounces/jumps/flutters all the time (it bounces 1/2-2 psi of its reading with engine running) so there may be a little normal back surge of fuel. Its a lot more steady with the engine off and lift pump pushing on a closed fuel solenoid.

[DonovanNorway]

Not many in my area have the scan tool.... That is why I have ordered the AllinOne OBDII cable for PC. Hopefully if I don't figure it out before it arrives there will be some DTC codes to look at.

Otherwise to answer the last appreciated input. I am getting diesel to the injectors but only three at a time before the IP stops pumping. I have followed the lines all the way to the lift pump to confirm that the correct fuel line is being used, just to be certain I looked on my sub as well, its the same. Starting to wonder if it the PMD that is the problem. Only problem is is that I can't switch with my sub since it is a 95 and not 98.

[Bnave95]

Not many in my area have the scan tool.... That is why I have ordered the AllinOne OBDII cable for PC. Hopefully if I don't figure it out before it arrives there will be some DTC codes to look at.

Otherwise to answer the last appreciated input. I am getting diesel to the injectors but only three at a time before the IP stops pumping. I have followed the lines all the way to the lift pump to confirm that the correct fuel line is being used, just to be certain I looked on my sub as well, its the same. Starting to wonder if it the PMD that is the problem. Only problem is is that I can't switch with my sub since it is a 95 and not 98.
You said You tried the FSD off of the 95 with no change though quote switching the PMD.
We think of these two terms as being the same.
Wounder if you might be saying PCM/ECM and then your right the 95 will not work in the 98.
How much of the fuel have you tested for water?

[Hubert]

Question- When they bench test an IP doesn't test bench communicate with PMD and check all functions of the IP, timing, fuel metering, fuel flow etc????. So IP should be good right????

On board the truck the ECM makes the commands. It delegates control to subsystems tranny, IP etc. The PMD/FSD precisely controls fuel rate and injection and the ECM monitors everything. When the ECM is not happy with results of input commands it shuts down the engine via the fuel shutoff solenoid.

Triple check connections at the PMD/FSD and engine harnesses for bent pins etc. Is the fuel calibration resistor present? They may take it out for bench testing. I have read many posts and still not sure what happens if resistor missing some read the truck won't run some read the programming defaults to No. 5 resistor value and depends on TDC offset relearn. Maybe the ECM being powered down for 2 yrs it lost its TDC offset and ECM is not happy with first few revs of motor expecting it should be running or sensing some combustion acceleration and since it is not the ECM shuts fuel back off because the PMD/FSD is not communicating correctly ???

[DonovanNorway]

Hi Sorry about the confusion I did mean ECM and not PMD. The only problem is, is that I cannot rev the motor because it stops squirting fuel after three times (by this I mean the the relay at the back of the pump will only click 3 times- tested many times with 5v light bulb) always 3. I even checked when turning the motorover manually with wrench that after the crankshaft sensor had registered new "tooth" the light would blink but again only 3 times even when manual.

Yes when they test it on the bench the PMD is also tested. I have gone over all the wires several times and checked them also with an OHM meter and everything looks good. Shut off relay or solenoid on the top still has power even though it quits pumping so it is not the shut off solenoid that stops.

[DonovanNorway]

I have pumped out about 3/4 of a gallon so far with the lift pump during my tests, no water is present in any of the testing.

[DonovanNorway]

how does the PMD know when to open solenoid on the back of the pump? Is it only the crakshaft sensor that controls this or are there are things as well?

Since the shutoff solenoid is still open after it stops pumping maybe it cannot be ECM. I have a light hooked up to both the shut off 12v and the back of pump 5v. that is how I know which stops.

[Hubert]

Its a combination of the optic sensor, crankshaft sensor, and alternator (rpm) signal that the ECM knows what the engine revs are doing. Then its a whole host of other sensors it keeps up with coolant temp, boost, IAT, and throttle position ect ect to map the fuel delivery. I would guess its ECM controlled driven via the FSD with input from the throttle position sensor. But iirc the ECM ignores the throttle position sensor until the truck is running (probably something like a few firing cycles because you can rev motor on start up but cannot force it to inject fuel from drivers seat with right foot until the computers happy) Its fly by wire and electronically started no control from operator/driver except turning the key.

That was my understanding about the ECM shutting off fuel at the shut off solenoid when its not happy with expected results. Its suppose to safeguard against run away rpms. If ECM can stop injections with fuel metering solenoid and it hasn't freaked out and shut off all fuel with the fuel shut of solenoid it sounds like the ECM just isn't happy commanding fuel injection for some reason.

You could read the long post by GMCTD on the logic behind the timing contol and optic & crankshaft sensors vs the timing chain and how the electro/mechanical adjustments are made and why. I can't do it justice by any means.

How about the fuel calibration resistor. Turbinedoc has said that when the ECM is commanding new timing offset (or timing control) it must read fuel calibration resistor value or it won't start. That could be causing the ECM to stop commanding fuel injecting???? But thats real muddy water because some say it will default and still run at No. 5 default value.

OK I'll shut up now because I am way past my actual hands on working knowledge ... good luck.

--------------
on edit the ECM relearns the timing offset once the coolant reaches a min temp so I am not telling the whole story (I doubt I could start over and clarify). Sorry to muddy the water but there has been discussed the requirement for a calibration resistor for some scenerios but ok missing it at others times. This might be one of those times it needs to know calibration resistor to run? - ok now I'll shut up I tried to clarify one point.

[DonovanNorway]

hmmm The four wires running to the FSD. *The light green (signal back to PMD from FSD??) starts at 2 volt when just trying to start after 1 second it drops to under 1 volt. The Red (to the FSD from PMD??) has a steady 5v. Gray 12v in and black???

another thing I am considering is that when I first turn the ignition on the security light appears for about 10 seconds. If I then leave the ignition on it comes on again after 30 seconds and stays on. Is this normal??
maybe its the key security thats the problem?

Donovan

[gmctd]

The Fuel Solenoid Driver becomes the Pump Mounted Driver when mounted to the side of the Inj Pump - same module, different acronyms.

The Powertrain Control Module switches the Fuel Solenoid thru the FSD\PMD to control injection.

Those signals do not appear to be correct, at this time - check the owner's manual for Vehicle Security operation

[DonovanNorway]

Well its been awhile but I have tried so many different things and nothing is helping. The last thing I tried was to read DTC Codes from ECU but could not connect to it from scanner. I then borrowed a 1999 Tahoe and the scanner worked well on it. I then took the ECU out of my pickup and stuck it into the Tahoe and it would not start but since the security light would blink it was probably because of key security. I could however access the ECU from the scanner, but no codes popped up it was blank. But I did recieve engine temp etc. I then put the tahoe ECU into the pickup and the test light on the back of the pump blinked the whole time I turned the motor over. It would not start but again probably due to key security.

I then put the old computer back in and still cannot read the ECU. I then decided to take the dash out to see if a mouse had eaten the wire but everything looked good. After that I checked what type of electricity that was delivered to the OBDII data link, and this is what the tahoe had.

first wire top left: 0volt; color: purple
second wire top middle:ground; color: black
third wire top middel: ground; color:black/white
fourth wire top right: 0volt; color:black/white
fifth wire bottom left: 5volt; color: Tan
sixth wire bottom middel:11,5volt; color: Green
seventh wire bottom left:11,5; color: orange

Now pickup with one wire less**
first wire top left: 2,5volt; color: purple
second wire top middle:ground; color: black
third wire top middel: ground; color:black/white
fourth wire top right: 11,7volt; color:black/white
No Tan wire****
sixth wire bottom middel:0volt; color: Green
seventh wire bottom left:11,5; color: orange

That makes me wonder a little, plus think that the 99Tahoe has a differnet system then the 98 silverado.

Is that correct?

[gmctd]

Clarification - all OBD2 Diesel PCM's are identical, except - and this is where it is very important that you fill out your sig line describing your main ride, as well as posting data for the one in trouble -

the MEMCAL chip, which runs the engine in 'LIMP' mode, is set up for

"S" engines - manual or automatic, and manual or automatic 4wd
- EGR, MAF in '98 ^

- OR -

"F" engines - manual or automatic, and manual or automatic 4wd

An "S" PCM may not run an "F" engine - too many DTC's, no MAF input

An "F" PCM will run an "S" engine

A manual trans PCM will run an automatic trans engine, but with no gear shifting

An automatic trans PCM will register all the DTC's for the missing automatic trans, and may not start a manual trans engine

An "S" automatic PCM can be reflashed to an "F" automatic PCM, and vv

An "S" manual PCM can be reflashed to an "F" PCM, and vv

Neither PCM can be reflashed from a manual to an automatic, and vice versa, because the MEMCAL is specific

"S" engines have EGR, and MAF after '98

"F" engines do not

OBD2 is a 16-pin ALDL connector
1 -- 2 -- 3 -- 4 -- 5 -- 6 -- 7 -- 8 top row, left to right
9 - 10 - 11 - 12 - 13 - 14 - 15 - 16 bottom row, left to right

Were some early euro OBD2 units shipped with the 12-pin ALDL

F - E - D - C - B - A top row, right to left
G - H - J - K - L - M bottom row, left to rignt

[bluuzman]

This may sound stupid but someone earlied suggested checking that diesel is actually being injected....

Have you checked / are you sure the injectors are operating properly?
If there is a fuel spray, the glows are good and engine spins, it should fire if reasonably warm.

I do not have the calibration resistor and my '95 sub K2500 runs just fine. Maybe some day it won't start - who knows ;) I've read somewhere that if there is no calibration resistor the engine uses some default value.

A few years ago I had some trouble with a mechanical Bosch (K?) Jettronic and tried several replacements for the fuel injection unit. None of them worked although the "dealer" said they all have been removed from good vehicles. They just had been sitting a year or two in a barn....

-a

[More Power]

1999 was the first year for the new body style Silverado. I don't know for sure, but it could be that GM used the GMT-800 electrical systems in the GMT-400 carryover body style.

Jim

[moondoggie]

Good Day!

To summarize:[list]
The LP (lift pump) is getting fuel to the IP (injection pump). I

[DonovanNorway]

Thanks for the replys everyone.

Moondoggie, your summary is correct, and yes I did mean PCM or ECM. when I started writing this I though unit instead of module thats why the mistake.

regarding the Data Link connector issues. The Tahoe I used was a automatic, and the pickup manual. Would the automatic have the Tan whereas the manual does not have it?

[DonovanNorway]

YAHOOOOOOOO!!!! I finally got it started!!! I found a wiring schematics for the Data Link Connector and found that the purple wire in slot 2 is splitt up several times between the ECM and Data link, first to Passkey, then to Power Brakes Module, third to Transfer Case (automatic only). I then kept checking the volts of the purple wire while removing one after the other. (I did not like that I had 2,7v on that wire.... I figured it was either to little or to much my thought was 5 or 0) when I unplugger the connector for the power brakes module the volts dropped to 0, I then hooked up the computer to the ECM and YES YES YES I could read data, hooked light up on fuel selnoid on back of pump and again it blink like an S.O.B. That gave me a smile cramp!!!!! I threw the air intake on and the dashboard back in (not a so easy task...) and it fired up on the first crank!!!

Again thanks to all of you who have helped!! And who would have thought that ABS can keep your motor from starting:-(

[moondoggie]

Good Day!

Congratulations, & thanks for posting your fix. Now it'll be searchable by all of us when similar happens to us.

Sorry I wasn't anywhere near helpful; my desire to help often overcomes my abysmal lack of knowledge. My trucks have been very reliable (good news), so I don't get any practical experience fixing stuff (good news/bad news).

Blessings!
(signature in previous post)

[gmctd]

The '98's were the initial approach to the concept of computer management of all the functions in the entire vehicle, where the vehicle has it's own little intra-net, with all the computers talking to each other.

Any individual computer goes down, where it loads the intra-net, and the others may not function, even preventing diagnostics thru the ALDL.

Turbine Doc's '98 Sub just had similar problem - disconnect the ABS to restore PCM function - but his engine would run, just not very well, and with no data to the scanner.

Chrysler also initialized that scheme in the Diesel trucks in 1998 with the 24v Cummins, based on the Mitsubishi scheme designed back in the early '80's for the turbocharged vehicles

Makes it very difficult to modify and\or switch engines\transmissions, even instrument clusters, across the product lines.

Alas, poor shade-tree mechanic..................