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’95 K2500 Suburban no-start issue


John's Trucks

Question

First off, I'm a new member (see my new member thread), and I came here because you have a "speak to a tech" forum and I have a puzzling no-start issue.

 

This post is likely to be long and a bit convoluted as the no-start issue has been a bit of a bugger to figure out what’s going on. Also, I’m a bit of a perfectionist, so I like to analyse issues fairly methodically and in some depth. My sources so far have been the Autozone web site and a Haynes manual, which I find to be less helpful these days than they used to be.

  1. Vehicle info and history

 

’95 K2500 Suburban 4x4: VIN 1GKGK26NXSJ751339: current mileage - 374,363.6 km

Basic Vehicle Specifications (from RPO codes)

L19: Engine:7.4L, 1TBI, V8 / FE9: Certification: Emission, Federal / NA5: Emission System: Federal, Tier 0 / K68: Generator: 105 Ampere / MT1: Transmission: 4L80-E, 4-Speed automatic, Electronic / KNP: Transmission, Heavy Duty Cooling System / GT4: Rear Axle: 3.73 Ratio / G80: Rear Axle: Positraction / JD7: Brake System: Hydraulic Power, Front Disc, Rear Drum, 8400 Lbs / Z82: Trailer Provisions Special equipment, Heavy Duty / No code : Trailer brake controller and seven pin connector / C6P: 8600 Lbs. GVW Rating / Z49: Export, Canadian Modified Mandatory Base Equipment.

 

History

The truck was purchased privately in October of 2009, and its previous use was mainly as a race car hauler. Since then there have been several issues including ABS problems, fuel pump and fuel line, distributor, front hubs, accessory belt tensioner, exhaust system and water pump, and a few lesser problems. The truck has always been parked outside, and the current issue presented itself in early February this year, first as a no start problem (starter solenoid clicked but no engine rotation) whenever the temperature got below 15*C, especially when parked in the wind. Plugging in the block heater helped to start the engine, but not when the temperature got down to 20*C or so. In mid February we got a warm spell, so I tried to start the engine so I could move the truck out of the wind. The engine started, ran OK for a few seconds, then coughed a bit and quit, and after that it would turn over on the starter but not start, and that is the condition up to date.

 

Over the time I’ve had the truck I’ve had to replace several components, and the following are those for the ignition, fuel, intake, and exhaust systems which may impact on the current problem:

  • Jan. 18/10 – new fuel pump
  • Jan. 27/10 – new coil – ACDELCO D503A
  • Mar. 8/10 – new fuel pump relay (spare)
  • Apr. 15/10 – new distributor ( GM dealer) – N023610 (not sure if it included new ignition module, pick-up coil and cap and rotor)
  • Jun. 24/10 – new Bosch Premium ignition wire set (old wire set had some suspect resistance readings) – discovered later on the Turbobricks (Volvo) web site that Bosch wire sets don’t have the best performance
  • Jul. 23/10 – new air cleaner to throttle body gasket
  • Aug. 5/10 – new gauge and ECU temperature sensors
  • Aug. 24/10 – leaking underbody fuel line replaced
  • Sept. 20/10 – new cat back exhaust system
  • Mar. 9/12 – new coil – Standard Blue Streak DR37 (previous ACDELCO D503A coil gave suspect readings)

 

Preliminary Tests

  • No trouble codes
  • Fuel pump cycled with the ignition key on “start”
  • Fuel at throttle body when cranking
  • Under hood electric centre fuses OK, both new (spare) and old fuel pump relays OK
  • Got spark with in-line spark tester on coil and all spark plug leads (but looked a bit weak)
  • Pulled, cleaned and gapped all plugs – don’t know how old they are but condition looked OK, insulators brown and no fouling, etc.
  • Camshaft turns over when cranking (tested at #3 cylinder through the oil filler hole – valves working)
  • Tried to start again – no change

 

At this point I realized that in-depth analysis would be required, so I dug out my Haynes manual and got to work as time and weather conditions allowed. I’m posting this part now to give an overview and will post the in-depth testing later after I’ve had time to review and organize my notes and findings.

 

Oh yeah ... I hope you like long stories. :fingersx:

 

Also (senior moment) I forgot to mention that I did a search on this board and didn't find a similar issue.

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Hey, fellas, I won't bite ... at my age I don't have enought teeth left. :rolleyes: And a member of RCEME (or whatever our uni-forces are calling it these days) shouldn't be afraid of messing with an old Suburban. :P I was in the RCE Cadets and Militia back in the '50s, and you lads were always handy to have nearby when our trucks broke down. :seeya:

 

Sarsfield is on the eastern fringes of the Mini-mega City (aka Ottawa or "Disneyland-on-the-Rideau"), and I'm about 1 1/2 miles south of the village on a concession road.

 

I haven't started the second part of my saga yet as I got side-swiped by Haynes yet again, and had to go to Autozone for the correct info and re-do a couple of tests. Haynes books these days really aren't as good as they were a few decades ago. :nonod:

 

That's about it for now, time to organize my notes and get typing ... other vehicle and household problems permitting. :sigh:

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Possibly, but I don't think so as I've already done this test ...

 

Miscellaneous checks/inspections, etc.

...

  • Engine rotated by hand to TDC #1 cylinder with plug #1 removed - verified piston at top of stroke – verified distributor rotor points at #1 post on cap

 

...

 

 

... but I'll do the test again (when it stops raining :happysad: ) just to be sure.

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Well, we may have found the culprit.

 

I did two tests today, #s 5 and 6 on page 5 of the Easy Auto Diagnostics web site here: http://easyautodiagn...gn_module_5.php.

- TEST 5: Testing the Ignition Coil for 12 Volts - probed the pink wire between the coil and the ignition module with my digital multimeter - got 12+ volts.

- TEST 6: Verifying the Ignition Coil's Switching Signal - probed the white wire between the coil and the ignition module with my LED tester - LED flashed on and off - this indicates that the ignition module and pick-up coil are good and the ignition coil is bad.

 

I mentioned in the big write-up I first posted that the new coil (Standard Blue Streak DR7 [made in USA]) failed one of the grounding tests, but as it was brand new I thought that it couldn't be an issue. Looks like I guessed wrong! I'll be taking it back to the shop I bought it from for a replacement, and I hope I don't get any hassles from the coil being installed as I think ignition part warranties are void if the part is installed.

 

I didn't go on to testing the pick-up coil as the Test 6 flashing LED indicates it's OK.

 

That's it for now,

 

John

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First, some items missed in my first post

  • Jan 22/11 – new battery – Canadian Tire Motomaster72 – GP34/78DT – 800 A cranking @ 0*C, 650 A cranking @ -18*C, 100 min. reserve capacity
  • Nov ?/11 – all engine compartment grounds checked and cleaned
  • Feb 11/12 – battery replaced by Canadian Tire due to weak cell – same specs as above
  • Ignition system – HEI with remote coil, no vacuum advance and no capacitor

 

  1. Into the bowels of the beast – Feb 18/12 to present

 

 

First off, due to the downsizing of GMC trucks after 1988, and the ride height with a 4x4, I find it really hard to work in the truck’s engine compartment. Due to this I didn’t use the test sequence in the Haynes book or Autozone’s on-line trouble shooting but started with those parts easier to get at, hoping that I could find a fix quicker and easier. I didn’t. :nonod: Secondly, I haven’t had a new car since 1974 and all the used vehicles I now have, except for the motorhome, have early EFI and electronic ignition systems which are new to me. I’ve started to get a handle on my old Volvo 244s, but I’m a newbie to the systems in the Suburban. So, then, here we go folks, and you may want to skip though the first part posted above just to refresh your memory.

 

Cranking test

Repeat of the previous test – battery charger connected to maintain battery voltage - fuel pump runs – fuel at injectors – oil pressure good while cranking – no start.

 

Verifying presence of spark

Repeat of the previous test – re-tested with fuel pump relay installed and then removed – connected in-line spark tester to coil lead and a good ground – got spark when cranking but spark faded out to no spark after about 5 seconds of cranking – suspected coil or something else cuts off any spark after a short time.

 

ACDELCO Coil Test (new Jan 27/10)

Coil test points from Autozone illustration (see attachment below).

Coil installed during test – test procedure from Haynes and Autozone as in illustration below – results:

  • Test #1 – meter @ high scale – spec should be infinity – got no reading (no circuit?)
  • Test #2 – meter @ low scale – spec should be low or 0 ohms – got 0.7 ohms
  • Test #3 – meter @ high scale – spec should be no infinity – got infinity

 

Standard Blue Streak coil test (new Mar 19/12

Coil test points from Autozone illustration (see attachment below).

Coil installed during test – test procedure from Haynes and Autozone as in illustration below – results:

  • Test #1 – meter @ high scale – spec should be infinity – got no reading (no circuit?)
  • Test #2 – meter @ low scale – spec should be low or 0 ohms – got 0.7 ohms
  • Test #3 – meter @ high scale – spec should be no infinity – got 0.01 ohms

 

Coil test comments /questions

Both coils seem to have failed test #1 after trying with good grounds both at the coil mount and a good engine ground, and the ACDELCO coil failed test #3.

  • Is the ACDELCO coil no good, and if so why would it fail after only two years?
  • Both coils failed test #1, so is the Standard Blue Streak also faulty, or is there an error in the test procedure from Haynes and Autozone?

 

Battery voltage ignition tests

  • Tach test terminal connector @ coil harness end – ignition on – got battery voltage
  • Two terminal lead from ignition module @ coil end connector - ignition on – got battery voltage at both pink and white wires.

 

Pick-up Coil and Ignition module (igniter?) tests

Pick-up coil test points from Autozone illustration (see attachment below).

Pick-up coil installed during test – test procedure from Haynes and Autozone as in illustration below – results:

  • Test #1 – meter @ high scale – spec should be infinity – got no reading (no circuit?) – similar result as found in #1 coil tests – same question as coil test procedure?
  • Test #2 – meter @ low scale – spec should be 500 to 1500 ohms – got 766 ohms between connector pins

 

Note: Ignition module (igniter?) not tested – special equipment required – has to be checked by a qualified auto electric shop.

 

Miscellaneous checks/inspections, etc.

  • Cap and rotor cleaned and checked – age unknown but cap has no cracks, wear on inside of posts looks OK, all posts have continuity from inside to outside – rotor looks OK with no excessive contact wear – re-installed
  • Plug wires pulled and cleaned – exterior and connectors look to be in good condition – re-installed
  • Engine rotated by hand to TDC #1 cylinder with plug #1 removed - verified piston at top of stroke – verified distributor rotor points at #1 post on cap
  • Checked harmonic balancer condition for slippage – looks OK but best test would be with engine running using a timing light with marks on the balancer - can’t be done right now due to the no start condition

 

Second Cranking Test

  • Battery charger connected to maintain battery voltage - fuel pump runs – fuel at injectors – oil pressure good while cranking – no start
  • Gave her a good shot of Quick Start in the throttle body (butterflies fully open) and tried again – got a few sputters but no start
  • Connected in-line spark tester in coil lead – tried again and got a good spark while cranking for about 5 – 6 seconds
  • Connected in-line spark tester in #1 and then #2 plug leads (longest plug leads) and tried again – initially got a good spark in both leads while cranking but spark faded to 0 within about 5 seconds

 

Iginiton wire set resistence checks

Given the spark fading and the fact that I’ve had problems with the Bosch wire sets on my ’88 Volvo 240 even though the wires looked to be in good condition, decided to do a full wire set resistance check on the Suburban’s Bosch wire kit. Results as follows using Autozone’s specifications (in order of wires tested):

  • Coil wire – length 10.5” – spec range 3K to 10K ohms – read 0.393K ohms
  • #1 cyl. wire – length 35.5” – spec range 6K to 20K ohms– read 2.02K ohms
  • #3 cyl. wire – length 35.5” – spec range 6K to 20K ohms– read 2.12k ohms
  • #5 cyl. wire – length 27.25” – spec range 6K to 20K ohms– read 1.09k ohms
  • #7 cyl. wire – length 23.25” – spec range 4K to 15K ohms – read 1.52k ohms (unsteady)
  • #2 cyl. wire – length 39.25” – spec range ? K to 25K ohms– read 2.61k ohms
  • #4 cyl. wire – length 31.25” – spec range 6K to 20K ohms– read 1.52k ohms
  • #6 cyl. wire – length 27.25” – spec range 6K to 20K ohms– read 1.09k ohms
  • #8 cyl. wire – length 24.25” – spec range 4K to 15K ohms– read 1.97k ohms

 

Summary

  • The two coils are questionable, especially regarding the ground test (test #1) as noted above, and the pick-up also has the same questionable ground test.
  • The battery voltage tests indicate that voltage is getting to the ignition system.
  • The miscellaneous tests seem to show that the cap, rotor, ignition wires and plugs are in reasonably good condition, at least from an external inspection, and the static timing is correct.
  • The ignition wire resistance tests seem to show that they’re way below spec. Obviously, there’s something going wrong with one or more components that’s causing the spark fade-out, perhaps due a component failing under load/heat? Could the low ignition wire set low resistance cause such a condition?
  • If the ignition module is suspect it will have to be removed and taken to an auto electric shop to be tested, and if it’s the pick-up coil, there’s no instruction in the Haynes book on how to remove and install it, so I’ll need some instructions here.
  • If the Bosch wire set needs replacing, could someone suggest a better wire set for a K2500 Suburban with the 7.4L engine?

 

So that’s about it, folks. I could just keep replacing components until the truck starts, but that could be expensive and my budget’s in pretty bad shape right now, so any help with this problem would be greatly appreciated. :fingersx:

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Hey out there in interweb land, I know it's the Easter holiday and all that, but I really need to get The White Beast running so I'm gonna

 

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01111111111111000110000000000111001111000000000000000111111110000000

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11011100001111101111000000001111001111000000000011110011111111110000

00111100000111101111000000011110001111000000000111110011110111111000

01111100011111001111000000011110001111100000011111110011110001111100

01111001111100001111000000011110011111100000111111100011110000111100

01111111110000001111000000111100011111110011111111100011100000111100

11111110000000001111000000111100011111111111100111000111100000111100

11111110000000001111000001111000011101111111000111000111100001111000

11111111111000001111000001111000011100011100001111000111000111111000

01110111111110001111000011111000011100000000001110000111111111100000

01110000011111000111100111111000011100000000001110001111111000000000

01110000111111000111111111110000111100000000001110011110000000000000

01111111111111000011111101111000111000000000011100001110000000000000

11111111111000000001110001111000111000000000011000001111000000000000

11111110000000000000000000000000000000000000000000001111000000000000

01100000000000000000000000000000000000000000000000001110000000000000

 

this thread. :driving:

 

And I've also starred it to get your attention. :seeya:

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Grab whoist pull out the motor drop in a LSx.Problem solved!

 

 

Maybe, if I had the time and money ... which I don't. :nonod:

 

Gary,

 

I checked the cold cranking oil pressure and got 413 kP (+/-) after about 20 seconds. From the wiring diagram for the fuel pump oil pressure switch and sender it looks like low oil pressure cuts the battery power to the fuel pump from the ECM-B fuse. If that's the case, given the cranking oil pressure reading I got, I would think that the fuel pump oil pressure switch is OK?

 

 

I would agree.My engine starts after 3-5 cranking seconds(even after sitting all night),it only takes 4psi(28kPa,whatever that is)for the oil pressure switch to close and allow the engine to start.

 

Something you said earlier is bugging me....you said the spark at the spark tester was a good at first but faded after a few seconds,seems to me by the time the oil pressure builds up enough to let the engine start the spark has faded...makes me wonder :dunno:

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Thanks for the reply grampa ... we Old Farts have to keep together. :thumbs:

 

I tried to find the oil pressure switch in my Haynes book but it was next to useless; it mentions the switch but not much else such as location. Autozone o/l was better as they located it on the driver's side of the engine, but not exactly where, which is a bit of a puzzle as I have an ECT sensor on that side which is not shown their component locations. I guess I'll have to check these between showers as The Beast is parked out in my yard and we have two days of rain forecasted. :shakehead:

 

As for the parts you mentioned, how long have they been in and are you happy with them?

 

And if there's any GM techs on this board, feel free to jump in ... please. :seeya:

 

Oh yeah. As for the "bump," I found it a few years back on the Motorsports Club of Ottawa forum, but I don't know it's origin.

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You'll find the oil pressure switch on the lower part of the block,driver's side front,next to the damper pulley,down behind the power steering resevoir.It can be dark down there so have a flashlight handy.

 

This migh help:

62534222.gif

Just noticed,there's no #11 in the pic :dunno: ,it's the one down by the power steering lines.

(pic from ALLDATA)

 

I installed those parts in January of this year,all good so far :thumbs:

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Found it ... thanks. There seem to be no issues with the wires, so now I have to figure out how to test it as there's nothing in the Haynes nor Autozone. Are you signed up with Alldata, and if so, is it worth the cost and can Canadians subscribe?

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Found it ... thanks. There seem to be no issues with the wires, so now I have to figure out how to test it as there's nothing in the Haynes nor Autozone. Are you signed up with Alldata, and if so, is it worth the cost and can Canadians subscribe?

 

 

Yes,I signed up and to me it's worth it to me,but it has to be re-newed yearly.There are discounts for multi-year subscriptions & adding other vehicles(which I intend to do soon).There is a ton of info there,everything you'd want to know about your Burb,TSBs,recalls,wiring diagrams etc.I would think it's available to our northern neighbors,can't imagine why it would'nt be.

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Grab whoist pull out the motor drop in a LSx.Problem solved!

 

 

Maybe, if I had the time and money ... which I don't. :nonod:

 

Gary,

 

I checked the cold cranking oil pressure and got 413 kP (+/-) after about 20 seconds. From the wiring diagram for the fuel pump oil pressure switch and sender it looks like low oil pressure cuts the battery power to the fuel pump from the ECM-B fuse. If that's the case, given the cranking oil pressure reading I got, I would think that the fuel pump oil pressure switch is OK?

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