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Old 08-03-2018, 12:44 PM   #1 (permalink)
jnymdnyt
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Chevy G30 6.5 V8 Cranks but won't start

Hey Guys, This is my first diesel engine and I've spent the last 3 days trying to figure this out the main cause with the use of a service manual and some internet information and stumbled upon this site. Today, I am taking a different approach and see if I get somewhere. I've read the "FAQ for newbees" and have posted the diagnostic checklist below:

I will say that this is the most methodical approach and I'am glad there is a website like this.


The Diagnostic Checklist:
Please fill out to best of your knowledge.

1. Describe the problem you are having in detail:

Bus will crank but won't start. First off when I bought the bus it was stuck on 2nd (and reverse) but wouldn't shift to higher 3,4th gear. Thinking it was due to low voltage or something electrical I had the batteries checked to eliminate that issue and replaced the one under the hood but not the second one since it was showing 13V. I installed it and it started fine. I checked the OBD1 scanner and it was not communicating with my ECM so I tried a couple of times again. I then noticed the the "WTS" wait to start light was not illuminating anymore and when I tried to start it again it would just crank and not start like it always did. Checked all the fuses and they were all good. I checked the fuel supply and it was getting fuel up the the fuel filter management and "t" handle drain but when I loosen the injection line at the injector It doesn't get any fuel when I crank it over. I also noticed that it was leaking fuel under the FFM due to a worn o-ring seal. It also sat for a month but started first click when I got back so I probably have to change diesel soon.

2. Year of truck/engine. 1995 Chevy G30 Detroit diesel 6.4 V8
3. Odometer reading (indicate miles or kilometers). 345k miles
4. Indicate the model number on the Injection pump (starts DS4 or DB2......). Will check.
5. Indicate if you know if its a 1500, 2500, 2500HD, 3500, 3500HD. Don't know
6. Do you have an EGR on the engine? (An F or an S engine code 8th VIN digit) "Y"
7. Air Filter condition (visual check). Cleaned it
8. Fuel filter condition (freshly changed, mileage since changed). Don't know exact age but looks good.
9. Location of PMD/FSD? (ex. on pump/remote over intake, behind bumper). Will look for it.
9a. If remote mounted, describe wiring harness (homemade or purchased from which vendor). TBD
9b. Indicate the location and condition of the FSD/IP grounding wire. TBD
10. Outside Temperature (C or F). __65F___

11. Service Engine Light while running?- on/off/intermittent ON
11a. Service Engine light does glow during start/cranking/bulb check: Yes
12.Have you scanned for engine codes? Yes
12a. List exact results on engine codes. Didn't get any

13. Condition of Battery terminals (removed, cleaned and tightened). Clean and new
14. Known condition and age of Batteries. 1 is less than 4 and the other is new
14a. Are batteries a matched set of same age? No
15. Condition of Major Grounds (removed, cleaned and tightened) cleaned and tight.
15a Have the batteries been individually load tested? Yes

16. Does engine crank, or "turn over"? Yes
16a. Does engine start and run? no
17. If engine does not start- Crack injector line: do you have fuel? No
18. Does your Wait To Start light come on? No
18a.Number of seconds WTS light is lit. N/A
19. Engine Cranking speed (if you have an accurate tachometer). No accurate figure but cranks very strong.

20. Are you experiencing Stalling? N/A and didn't stall when it was running
20a. Describe the event (upon startup only, down the road, hit a bump, etc...)
20b. Do you notice loss of dash or instruments? Instrument cluster lights went off
21. Check turbo inlet and air filter for obstructions.N/A
22. In a no-hot start, pour a bottle of room-temp water on the injection pump. Does it start now? N/A
23. Lift pump test - Describe results. Working Fine

24. Upon cold start, does the radiator hose get hard quickly? No
25. Upon cold start, do you have excessive white smoke? Yes
26. Do you have excessive cranking time before the engine starts? N/A
27. Have you used the block heater? Does it affect engine starting? (only try for starting problems). N/A
28. Are all glow plugs in proper working order? New

29. During hard acceleration, do you have excessive black smoke? Not when it started
30. Do you have any unusual exhaust smoke issues? Just when starting.
31. Turbo check out - Pass/Fail - N/A
32. Indicate fuel that you are using: Bio-Diesel, #2 Diesel, SVO/WVO, other Diesel
32a. If running Veggie Oil fuel setup, indicate details of your conversion (homemade or packaged system). N/A
33. Are you using any fuel additives? If so, please list.
34. Upon unscrewing fuel cap, do you have a large vacuum formed in the tank? Yes
35. Do you have any service history available that might pertain to the problem you are having? NO
36. Please indicate any modifications to the vehicle that might help us diagnose better. Moved ECM under the driver seat.

Please let me know if I am missing anything and thanks in advance.

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1995 Chevy G30 Detroit Diesel 6.5L School bus
4L80E transmission
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Old 08-03-2018, 06:05 PM   #2 (permalink)
JMJNet
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You need to do LOAD TEST on batteries not Voltage test.
Batteries can pass voltage test but not LOAD test which measure the amp-acity (amperage capacity) of the battery.
I had battery with good voltage but when the load is applied, it shows some shortage aka voltage goes to 0.

Just saying.

Besides, replacing 1 battery in this truck can be detrimental to the new battery.
In other words, the old battery will take out the new battery to go bad.

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1995 GMC Suburban:
PMD in Bumper
Leroy Diesel Flight System PMD
Leroy Diesel Oil Cooler Line
4" Warpspeed Exhaust
Kennedy Diesel LP/OPS Harness
Bosch Duraterm GP
Heath Turbo-Master
AD244 Alternator

Last edited by JMJNet; 08-03-2018 at 06:06 PM.
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Old 08-03-2018, 06:15 PM   #3 (permalink)
Tomcats
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You should not have a vacuum in the tank. Leave the fuel cap loose for now or do the fuel cap mod in FAQ's
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94 C3500 Turbo Diesel Dually Crew Cab long bed. 3-inch down pipe 3-inch exhaust no cat no muffler, Snorkel open, boost gauge, fuel pressure gauge Re-manufactured F-series Jasper engine 50,000 miles, now nearing 100,000 miles Zero.001% blow by PMD 4 years IP DB4 S5068, last replaced under warranty 100 years ago.
Leroy Lift Pump wiring harness.
4.10 gears

Member #1149 of the 3500 Dually Club!


Latest Project No Past History.
97 C3500 6.5 Turbo F series Straight Pipe No Cat 300,000 Miles looks to be rebuilt. Still sitting where I parked it a few years back. Finally started removing things in search of an injector or head problem.
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Old 08-03-2018, 06:16 PM   #4 (permalink)
Tomcats
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How did you perform the lift pump test, as in FAQ's?
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94 C3500 Turbo Diesel Dually Crew Cab long bed. 3-inch down pipe 3-inch exhaust no cat no muffler, Snorkel open, boost gauge, fuel pressure gauge Re-manufactured F-series Jasper engine 50,000 miles, now nearing 100,000 miles Zero.001% blow by PMD 4 years IP DB4 S5068, last replaced under warranty 100 years ago.
Leroy Lift Pump wiring harness.
4.10 gears

Member #1149 of the 3500 Dually Club!


Latest Project No Past History.
97 C3500 6.5 Turbo F series Straight Pipe No Cat 300,000 Miles looks to be rebuilt. Still sitting where I parked it a few years back. Finally started removing things in search of an injector or head problem.
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Old 08-03-2018, 06:18 PM   #5 (permalink)
Tomcats
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Also no wait to start may indicate a faulty glow plug controller.
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94 C3500 Turbo Diesel Dually Crew Cab long bed. 3-inch down pipe 3-inch exhaust no cat no muffler, Snorkel open, boost gauge, fuel pressure gauge Re-manufactured F-series Jasper engine 50,000 miles, now nearing 100,000 miles Zero.001% blow by PMD 4 years IP DB4 S5068, last replaced under warranty 100 years ago.
Leroy Lift Pump wiring harness.
4.10 gears

Member #1149 of the 3500 Dually Club!


Latest Project No Past History.
97 C3500 6.5 Turbo F series Straight Pipe No Cat 300,000 Miles looks to be rebuilt. Still sitting where I parked it a few years back. Finally started removing things in search of an injector or head problem.
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Old 08-03-2018, 06:26 PM   #6 (permalink)
Sirleitet
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Un-screw the gas cap first, then check if the glow plugs are working with a multimeter, and finally do the lift pump test before moving on to something else.
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1995 Chevrolet Cheyenne K2500 6.5TD / Suzuki Katana GS650G
Mods: Racor 690r fuel filter/w heater, new front face, new radiator and support bushings. Repaired both cab corners & frame. (Rust.)
Relocated PMD, DIY extended wiring harness. # of PMD replaced since owned truck in 2013: 5.
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Old 08-03-2018, 06:29 PM   #7 (permalink)
TDexter
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Quote:
Originally Posted by JMJNet View Post
You need to do LOAD TEST on batteries not Voltage test.
Batteries can pass voltage test but not LOAD test which measure the amp-acity (amperage capacity) of the battery.
Glad to hear somebody agrees with me about testing a battery.
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Old 08-03-2018, 07:51 PM   #8 (permalink)
TDexter
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Quote:
Originally Posted by jnymdnyt View Post
34. Upon unscrewing fuel cap, do you have a large vacuum formed in the tank? Yes
Are you sure it was vacuum and not pressure? I checked my cap by removing it and cleaning the threads with a clean rag. I put my mouth around the threads and blew, could not blow through it. I then sucked on it and it was clear, pulled air no problem. Cap has a one way check valve that allows air in but not out. Normally has pressure on the tank. Please no comments about my testing method, I know how it sounds.

If the bus was running and then the WTS light quit coming on and the bus wouldn't start, it just seems to me that the glow plug system has taken a crap. I would test that first. JMO
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Last edited by TDexter; 08-03-2018 at 07:51 PM.
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Old 08-03-2018, 08:00 PM   #9 (permalink)
JMJNet
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Bad battery will cause WTS light aka GPs to not function.

It takes a lot of amperage to operate the GPs.
In a 95, if we unhook the batteries, the GPs will not turn on the first start after that.
That may be the same quirk.
Bad battery will cause no electric which means it is similar to the action of unhooking the batteries..
__________________
1995 GMC Suburban:
PMD in Bumper
Leroy Diesel Flight System PMD
Leroy Diesel Oil Cooler Line
4" Warpspeed Exhaust
Kennedy Diesel LP/OPS Harness
Bosch Duraterm GP
Heath Turbo-Master
AD244 Alternator
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Old 08-03-2018, 08:27 PM   #10 (permalink)
jnymdnyt
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First off, thanks to all that responded. All good points.

Quote:
Originally Posted by JMJNet View Post
You need to do LOAD TEST on batteries not Voltage test.
Batteries can pass voltage test but not LOAD test which measure the amp-acity (amperage capacity) of the battery.
.
I had the battery checked both for voltage and load tested okay.

I am going down the list of all possible "will no-start cold" list per manual.

FUEL SUPPLY:

a faulty fuel filter.
b quality/grade or incorrect fuel (most likeliest cause per manual)
c air leaks fuel suction lines
d restricted fuel return line
e fuel tank cap not vented
f faulty injection pump
g faulty fuel supply
h water in fuel tank or filter
i faulty engine shut off solenoid
j inoperative fuel line or filter heater
k no fuel delivery

* As mentioned above, I check fuel delivery up to the fuel filter management and "t" handle drain and it delivers fuel but when I crack the injection line loose it does not get fuel. Now, if I have bad fuel wouldn't it still come out but just won't combust?

MECHANICAL SYSTEM:

a broken /scored piston rings (possibly not this because it started well when it did)
b incorrect rod bearing clearance
c low cylinder compression
d timing retarded
e timing advance
f starter cranking speed/batteries
g improper starting procedure

ELECTRICAL SYSTEM:
(this is what I suspect it to be but then again...)

a inoperative glow plugs (likeliest cause) I replaced all 8
b inoperative glow plug controller/relay
c housing pressure cold advance solenoid or switch

This came from the GM service manual. I posted it for future reference for anyone experiencing the same issue.

"Also no wait to start may indicate a faulty glow plug controller." my thoughts exactly

As far as the glow plug working properly, does the glow plug relay have anything to do with fuel delivery? Do combustion have to be present to suck fuel? my understanding was the PMD pump mounted driver was the one responsible for sending the signal to the injectors. So even with a proper working glow plug system if I don't get fuel it still won't start. Again, I am new at this.

"How did you perform the lift pump test"

I listened to the pump activate while someone started cranking the engine.

"You should not have a vacuum in the tank. Leave the fuel cap loose for now or do the fuel cap mod."

Do you mean leave the cap loose and then try to start it?

"Are you sure it was vacuum and not pressure?" It might be pressure.

"Bad battery will cause WTS light aka GPs to not function.

It takes a lot of amperage to operate the GPs.
In a 95, if we unhook the batteries, the GPs will not turn on the first start after that.
That may be the same quirk.
Bad battery will cause no electric which means it is similar to the action of unhooking the batteries.." I'm hoping that this is it. I checked how much a relay is and I might order one to eliminate this part.

I truly appreciate all your input as looking for a competent and trustworthy diesel mechanic where I am is hard and very expensive.

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