Under another posting, I described a number of drivability problems that I was having with my truck, this after dealer had installed a new HP pump 4 months earlier. Dealer replaced that pump under warranty, and now that I have it back it appears to run very well except for starting. It has always started perfectly, one bump after glowing it. With the new pump installed, and after glowing, the engine cranks for maybe 8-10 seconds before kicking off. Once it fires, it does so on all 8 immediately. Checking behind the truck, I would expect to see some smoke from excess fuel given the crank time, but I don't see it. Glow duration appears normal for the temp, and all glow plugs show continuity. Is there anything in the basic pump setup/install that could cause this, or do I need to chase yet another unrelated problem? Thanks for the help.


Jim

Any codes at all? How long do the glows stay on? That's just weird stuff. I'd think you'd be seeing some white smoke on bad glows. But no smoke? Almost sounds like no fuel. Any takers on that theory?

had a similar occurrence with one of my 7 warranty pumps installed.
started in 1-2 cranks before the pump was installed, afterwards it was
hard cranking for 5-6 seconds.

kept taking it back to the dealer - he tried to tell me the starter was
shot, then the battery's were weak, then my compression was low, then
my glows were weak,...all BS. i lived with it for 11 months until the
next PMD finally failed. took it to a different dealer for that one.
when i described the hard cold start issues since the previous pump he
told me it was one of 2 things - either the installer didn't set the
pump timing correctly, or the PMD was going bad right out of the
box. i don't know which it was, cuz the hard start issue went
away with the next pump/pmd.

The hard start purely coincided with the installation of this pump (1st pump failure at 132K I paid for...this pump at 139K is warranty). All basic operating parameters are verified: Cranking RPM, compression, glow system. Glow control appears to be proportionate to outside temperature 1st glow=7 sec @45 deg.F, followed by a short 2nd glow.


By the seat of the pants, it sure behaves like a lean condition. Working on this theory, I got up at 5am and did a data scan. CTS read 66 deg.F and IAT read 68 deg.F, this after an 11 hour cold soak after the engine had run for only a couple of minutes. The first time the pump was replaced, they also replaced the CTS. Are these readings skewed enough to cause start problems, or am I swatting at gnats again?


Thanks,


Jim

Without beating this subject to death, I really need some confirmation of my theories surrounding the difficult cold start. [Quantum Mechanic and TDG...I'd be flattered if I could hear your opinions]. I'm really kind of embarassed for the dealer. They are stumped and I believe going down all the wrong (redundant) paths. Yesterday, I called to check status and was told that they "had another 6hrs in it and can't find anything; that the glow system is working perfectly and the pre-pump delivering plenty of fuel. I restrained myself from saying "well no $h!t Sherlock".... All started with this new pump install. Temp sensor scans 25-30 degrees hotter than ambient. After spending many hours reading virtually every post on this site related to the topic, I challenge whether they performed the TDC offset correctly or at all. I'm actually going to bring them that procedure this morning and ask them directly if they performed (I'd do it myself but don't have access to a bi-directional scan tool).


Cranks 8-15 seconds after glow @ 45degF.; Please....comments on the above!


Thanks,


Jim

any chance they still have your old pump at the dealer so you could get the PMD off it and install it remotely for testing purpose, and if it fixed it you might decide to test it for longer.

Disconnect the Engine Coolant Sensor at cold start - compare starting time duration.


Disconnect Optical Sensor, start, and let run for about 15mins to clear fuel lines.


Did they replace the Inj Pump harness with the new pump?

Watch the Data display on the scanner during cranking, check CAM and Crank Pulse errors, they should stay at 0 or you have a sensor problem. Check CTtime, it should be towards the low end (1.5-1.7) during cranking with a new pump.

There is an easy test if you want to see if the pump is pumping on start-up.


One > leave a glow plug out and see if fuel sprays out on the first copula pumps.


Two> Take an injector and hook it to a line like you would if it it was a spark plug. See if it pops the injector.(I would use a spare injector and run it a little to purge the air to make the testing valid.)


Just cause the glow plugs have continuity doesn't mean squat. Put NEW Delphi plugs in. They glow in a split second.


Your injection pump is bad.

Good Pointers...thank you! I visited the dealer yesterday and the service mgr. was waiting to see me, very focused on getting my truck outta there (not fixing the problem). At my urging, they swapped out the CTS the night prior and it did start better (5 sec crank). Still I felt that the timing/TDC offset procedure wasn't followed, so I dared hand him a hardcopy and ask directly if it had been done. Frosty reception but he agreed to do it if I'd then go away. Picked truck up last pm, still longer than desired crank time....hhmmmmm.


I'm not a 'live with it' kinda guy! CTG, I wish I had more than a basic scanner that would read the Cam/Crank ref...I don't. GMCTD, I AM VERY INTERESTED IN WHAT YOU MEANT BY" DISCONNECT THE OPTICAL AND RUN FOR 15 MIN TO CLEAR LINES". What exactly would that do, and would it have any adverse effect on the TDC offset that the dealer has now set?


Thanks,


Jim

As CharlieP pointed out early on (I found and read your other post), cranking the engine with the CTS disconnected will point to glow problems, AND timing errors - both of which result in hard starting.


Intent was not to replace the CTS, which is a temperature-variable resistor, just disconnect it for a predictable result test.


If IP timing is retarded, engine will start easier.


If timing is advanced, engine may not start at all.


What happens when you crank the engine with (new) CTS UNPLUGGED?


Extended duration starting is also a symptom of air in injector pipes, particularly after IP replacement.


Minimum cranking RPM is spec'ed to ensure Inj Pump is turning fast enough to produce ~1700psi needed to 'pop' injectors - about 100 Pump rpm.


Engine idles at ~700rpm, IP is half of that for 350rpm, so engine will appear to run well, but still 'hard start' for low cranking rpm.


Problem is aggravated by air bubbles in pipes.


Running with Optical Sensor disconnected allows engine to start and run in 'limp' mode, such that PCM is not trying to correct for any discrepancy.


Air in Inj Pump will cause DTC-35 Short Closure Time.


Low voltage in Inj Pump harness will cause hard starting and possible DTC-36 Long Closure Time, where insufficient current is availale to drive Fuel Solenoid.


Can be result of poor ground connection - that small black wire tied to one of the Inj Pump cover screws is the only ground connection for the Fuel Solenoid and the FSD\PMD Module.


Could be Drive and Ground connections to actual Fuel Solenoid are loose.


Could be faulty Inj Pump Harness - oxidized\corroded and\or bad crimp connections.


Stanadyne found a significant number of actual harness failures, causing repeat failure complaint, such that each new FSD and new IP was factory supplied with new harness.


Bad load of fuel can also cause 'hard start\runs ok' complaint.


If Engine Coolant Sensor and Intake Air Sensor both read ~30deg high, as you indicated, either your scanner is faulty, or the entire engine harness needs some attention to grounds and connections.


And, no - unplugging sensor connectors will not affect TDC Offset or Desired (base) Timing.


Will affect Actual Timing, which is the desired test result.Edited by: gmctd

Thanks GMCTD...much obliged for the information. Sorry for not replying back sooner, however I was out of town at a trade show for a week and didn't have email access. Here's the latest:


Just before leaving for the show, I got the truck back from the steeler. They redid the TDC offset procedure and replaced the CTS (which was skewed warm). Truck still started a little hard...but much better. Deciding to check under the hood, I discovered that they had left one of the two batteries disconnected! I had not noticed a drop in cranking speed, but the engine lights off fine now at 40 degrees after a 1-2 second crank. On to the next issue:


While I was gone, my new vacuum pump, WG actuator and solenoid arrived. I spent the morning today installing, and it now runs like a new truck...I mean wow what a difference! After all this work, I decided to scan it again. Although the MIL is off now, it has stored two pending codes, a P0004 (Fuel Vol Regulator Control Circuit High) and a P0711 (Transmission Fluid Temperature Sensor Circuit Range/Performance). I elected the "clear codes" function, but these pending codes remain when I rescan it. Does anyone know if these codes can/will set the MIL on? Question #2 - Where is the trans temp sensor so that I can check it? Final question - (asked because I don't have a wiring diagram) - These 2 codes have been in there for some time now; is there a comon ground point or supply voltage that could be triggering both codes. Fixing this last issue will finally bring a long drawn out repair process to a successful close. Feedback would be much appreciated.


Thanks


Jim

Pull the dip stick on the tranny and smell the fluid, if it smells of varnish it's burnt.


Bad connections at the terminals will keep the glows from getting enough power to start the truck right and other starting problems like hearing click click click when it's real bad.

No burnt trans fluid...the P0711 is most likely a false code. Anyone else had this? Will the "pending" codes eventually go away? Maybe I just should not worry about them as they may have been there since before the pump was replaced. Opinions?

My scanner calls all dtc's pending till they're detected.

No reference for what that P0004 is - must be something your scanner software is interpreting.


VOL could be volume, or voltage. ????


Trans temp sensor is thermistor in valve body - could be dirty connectors, all located on driver's-side transmission case, main one up behind fuel filter.


I'd spend some time going over all the connectors and grounds in the engine bay - truck is 8yrs old - don't know if they still winter-salt the roads up there, but oxidation\corrosion is always a problem with water and copper.

Yes, I downloaded some images of the 4L80E and it does look to be a typical NTC for the temp sensor. I suppose that I'll start at the Trans harness connector and do a resistance reading there. Hopefully it's just that...a dirty harness connector.

Make sure the dealer put all the grounds back on the Intake Manifold. Curb side rear has two maybe three on the last stud. To swap out the IP the manifold must come off. IIRC all readers can read TDC settings, but only a few can reset them. Stock settings are -.25 to -.50 TDC. Your truck WILL start easier with a more aggressive number like -1.50 to -1.94 TDC.