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Gary
Gary, Chevy Technician
Category: Chevy
Satisfied Customers: 15695
Experience:  15 years GM master tech
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97 Silverado 6.5l turbo diesel no start problems. 135k

Customer Question

97 Silverado 6.5l turbo diesel no start problems. 135k miles. Running fine until a few weeks ago. Stopped for no reason, suspected gas contamination (still not sure if it was). Fuel emptied and fresh diesel filled. Was very hard to start but once started, ran fine for a week. A week ago, no start, and after extended cranking, started and ran fine for a day. Now, now start ...
Background: new PMD installed 3 years ago (remote location with heat sink) after a intermittent start condition.
Codes: P-1218 showing on MT2500. Resistor has never been installed in the PMD and has run fine without it for 3 years. No CEL.
Tested: Lift pump runs, Glow plugs cycle, fuel flows from T handle drain when key turned.
Return line on pump flows freely (tested with fuel overflow running to catch can while cranking).
Fuel shut off solenoid - piston removed yesterday (appeared functioning prior to removal) - #1 injector removed and engine cranked for 3 minutes in 30 second crank/5 minute wait to clear air from IP.
No flow at #1 injector during the above, or since.
PMD tests:
A to ground = 1.2v
D to ground = 12v
C to batt DVM ground = 12v
B & F = 0.6-0.9 VAC cranking.
Still No Start!!! Not sure what to do next. I have SO MT2500 with correct GM primary and troubleshooting carts, but not sure what to look for ...
Submitted: 4 months ago.
Category: Chevy
Customer: replied 4 months ago.
Should have mentioned that the FSO solenoid was refitted without piston, torqued down and no leaks.
Expert:  Roy replied 4 months ago.

good afternoon my name is ***** ***** I will assist

you have covered most of the bases with your checks. good job.

the one thing I see is the governor ring inside the injector pump may be the failure. without fuel being supplied to the number 1 line and injector, that is what pressurizes the fuel and routes it to the injector.

did you test any other injector line for fuel???

Roy

Customer: replied 4 months ago.
Governor ring? I have a DS4 manual and doesn't show a governor ring ...Checked #3 cyl ... no fuel flow.
Expert:  Roy replied 4 months ago.

yes. it is internal in the pump itself.

if you have good fuel flow out the return with no air, the pump itself is the only other possibility. have done many of these for this issue.

Roy

Customer: replied 4 months ago.
Really .... I could have thrown another IP if I just wanted to part swap until I found the solution to the problem.I am not sure that the symptoms are clearly IP (in that does not have intermittent running or stumbling issues). This is a starting issue: it will start sometime, hard start sometimes, and run OK for a day, and then not start for days.What I was hoping for was someone who would know what Tech-2 tests that I could use to see if the electronics within the IP were functioning (e.g. is the Fuel Control Solenoid was being energized by the PCM; the stepper motor commands, and the optical sensor readings). Although rare on these trucks, the PCM can also become intermittent ... it would be good to rule that out with Tech-2 tests as well.
Expert:  Roy replied 4 months ago.

ok, I will opt out and see if someone else will help you with all the tests. I dont and never used the Tech 2

good luck

Roy

Expert:  Gary replied 4 months ago.

was that 1.2 at the driver on step # 13 on the flow chart when cranking it over ?

Customer: replied 4 months ago.
Not sure which flow chart you are using .... it is step 19 on mine! I have substituted a good PCM, and get the same readings. (and the same no start).I'm really looking for Tech-2 test procedures to verify the internal electronic functions on the IP; can you help on that front? (particularly the Fuel Control Solenoid energization by the PCM; the stepper motor commands, and the optical sensor readings).
Expert:  Gary replied 4 months ago.

the diagnosis on these fuel systems and injection pump do not use a tech 2 for a basic cranks and no start with no fuel at the injectors

step 13 as seen on this chart

Customer: replied 4 months ago.
Step 13 in your chart does give a reading of 1.2v, and the rest of the steps point to the IP.The no start symptoms are not classic IP failure .. that's what's got me confused!I know that there are tests for the optical sensor and the stepper motor on the IP, I've seen something out there ... any thoughts?If not, I'll pull the optical sensor connection tomorrow (have to remove the plenum first, PIA) to see if it will start using default mode via crank sensor.
Expert:  Gary replied 4 months ago.

yes but the only thing to see on the scan tool is the pump closure time

but that is read with it running since the engine is not running the only thing left that is causing this problem with you following the tests step numbers is the injection pump with the cam sensor built into the pump being the issue especially with the code set of 1218 is a bad injection pump

this code chart here is all you need to follow but the engine needs to be running to follow that chart and to use the scan tool

following the chart i sent you should lead to a bad injection pump

you can always get me back for FREE for any follow up any time with this question even after you rate me here at Justanswer

if you have any questions please ask as i do not get credit for my work until you rate me here at Justanswer

Customer: replied 4 months ago.
Found the optical sensor tests ... sometimes Google works ... found the GM-US Army manual that sets out the test between the IP optical connector and the PCM (12OO+ PAGES). I'll test that tomorrow. The DS-4 IP manual seems to show that the stepper motor will not cause a no start.While I don't disagree that the chart points to an IP replacement, the P1218 is a missing calibration resistor code: nothing to do with the IP, and the PCM will set an internal setting (#5) for a missing resistor after 50 KO ops. Still not sure it is an IP issue ... any thoughts on PCM tests?