Hard to start - Extending Glow Plug time

[dbrannon79]

Good morning all, these problems just don't seem to end!!

After I have fixed all my fuel issues and got all the air intrusion out of the way, in the last week or two I have been noticing my truck is getting harder to start in the mornings and afternoons again after it's been sitting for several hours. this morning was the last straw as it took about 8 tries to get it to bust off!

one thing I have noticed is I can only get about 5 seconds out of my glow plugs on the initial key cycle. I can cross the glow plug relay for another few seconds and it fires up easier. what I'd like to do is somehow extend the time the glows stay on for the initial key cycle.

things I have done and tested already...

LP relay mod for OPS and also self primes with glow plug relay.

ECT sensor for the PCM is working, I have connected the laptop and verified the readings against a temp gun, gauge is accurate also.

Glow plug relay has not been replaced but I have tested voltage in and out to the glows. all seems to work fine.

September of last year I installed ac delco 60G's from AAP not that the old ones were bad, just did it as a maint thing. checked at that time that all were getting power.

during the "Texas Freeze" this past winter where it got down in the teens I had no problems starting up. but now in warmer (75- 80 deg) weather it just doesn't seem to start easy! Lately it's been getting more and more stubborn. each time the engine does bust off, it throws white smoke for a second or two until all cylinders are firing. this morning I was puffing smoke while cranking, about the 8th attempt when it finally fired up it was bellowing LOTS of smoke for a couple seconds. I took this as the last straw and I need to do something real soon!

one thing I did try to do in the past wanting to extend the initial delay time was adding a 1 watt 5 ohm resistor inline with the signal wire from the ecm to the glow plug relay after reading on another forum thread that this would give an additional few seconds but that didn't have any effect.

I need some help diagnosing my problem if the 5 seconds is just not enough time or if there is some other problem lurking around that I don't see. once the truck is running, it runs fine and doesn't smoke. also after that first startup I don't have any issues starting up again until it sits for several hours.

from what I've read online, the 60G's don't really get that hot as fast as the OE did but that was what my truck called for at AAP by application and I didn't want to use the bosch ones at the time since there were several reports of the spade terminals breaking off easily.

things I probably need to do... test resistance on each glow plug (not sure what they should be) but I will attempt that this afternoon at least the ones I can get to easily and post the finding if that will help. I may pull a couple from the drivers head and see what they look like too.

what else can I test or check to see even if the glows are my issue? any help is always greatly appreciated

 

[Big T]

I would look at replacing the crank position sensor.

How good are the batteries?

How about the starter? Is it cranking fast enough?

 

[dbrannon79]

I would look at replacing the crank position sensor.

How good are the batteries?

How about the starter? Is it cranking fast enough?

Actually I just replaced both batteries this past Saturday two diehard 1000ca batteries from AAP. it seems to crank over ok or at least sounds like it is.

I have not checked the CPS or the rpm that it cranks at. I think i can check this with the laptop connected to see what the pcm sees on cranking. Ill do this after work.

 

[dbrannon79]

I wonder if by changing the batteries did anything! last week both of mine died unexpectedly, I ended up stealing batteries from two other parked vehicles and running them until this past Saturday, bought two new ones and ended up having to re-do the cable ends on the passenger side since the last owner had converted it to top post. (one top post and one side) I soldered the cable lugs on for a good connection. Ill double check them and try using my amp clamp on the starter to see what it's drawing. and make sure I didn't goof up something like forgetting a ground wire!!

 

[THEFERMANATOR]

How old are the injectors? A 6.5l shouldn't need much if any glow time to start at 75-80 degrees. I know mine started like crap in Florida when my injectors went bad and started dribbling.

 

[dbrannon79]

How old are the injectors? A 6.5l shouldn't need much if any glow time to start at 75-80 degrees. I know mine started like crap in Florida when my injectors went bad and started dribbling.

I forgot about those! shortly after I bought the truck, and after Will and WW warned me on the disasters they can cause, not to mention the random misfire I was getting, I replaced the drivers side injectors and found the issue was the noise filter on the OP harness. here just recently when I replaced the turbo and did the valve cover gaskets I finally did the passenger side injectors. I think the drivers side have about 15k - 20k on them now.

very recently I had a slew if issues from hard starting to hesitating and bucking, where I found that air was getting into the fuel lines and my LP wasn't working due to my own foolish mistake. I was jacking around with the harness by the tank trying to see why my fuel gauge wasn't working and left everything disconnected including the ground wire there. little did I know that ground went to the LP and not the gauge. I've since fixed that, replaced the tank sending unit (removed the sock), new delco LP and added an inline filter between the LP and tank. all that stopped the air bubbles in the IP return. it did start up better and runs much better after fixing all that!

 

[Will L.]

Ohm check proved that worthless by having good plugs fail the test, and bad plugs pass it. Long explanation available if you want.

So remove and bench test glow plugs is only legit method.

Yes longer time needed. Plug in block heater a r compare results to see if more heat needed is problem vs trying injectors. Gm has no projected injector life, but we learned in the fleet to do them at 100,000 miles is best. 150,000 is most I would run them, after that they create issues. Leroy sells trustable set.

 

[dbrannon79]

ok, about to leave work and head home, I'll attempt to pull one and bench test for the 5 seconds that the truck is allowing it to be on.

I am curious, should I see it glow red in 5 seconds or less for the 60G's?

I'll also plug in the laptop to see the RPM while cranking and maybe rule out the CPS and the starter. I remember on some gassers of my year model, the PCM wouldn't start reading the rpm right away when cranking for whatever reason. maybe my truck is doing this also.

 

[dbrannon79]

Just got home. Plugged in the laptop and tried reading the rpm with the starter. Disconnected the PMD and cranked. 225 rpm

pulled the #1 glow out and it’s carboned up but cleaned up easily. Verified the part number on it as ac delco 427 0 100 274 107. About to try bench testing

when I left work. The first crank after the glows cycle didn’t start so I waited for a minute and tried again letting the glows cycle again and it fired up with a little smoke and a stumble

I haven’t wanted to but I may try wiring in a glow override tonight. I’ve been wanting to extend the time by default so my remote start would work with it!!

I’m already fearing the worst thing that my engine is just flat worn out being it’s 20k shy of 300k!

 

[Will L.]

How many miles on those injectors?
How much blow by?

Have you done a compression test?

 

[dbrannon79]

Maybe 20k on the drivers side injectors and just a couple hundred on the passenger side

It’s got a little bit of blow by not a lot

and no I’m afraid to! But if this proves everything is good I’m gonna have to! Will need to find someone to lend me one or try the HarborFreight one!

 

[dbrannon79]

I just found a melted glow plug wire behind the turbo down pipe. I’m pulling the inner fender on it now!

 

[dbrannon79]

Ya think this with cause my trouble?

that down pipe is awful close quarters where the third to the back glow plug wire comes out of the pipe insulator!!

lol don’t mind the natty light can in there. It’s my homemade heat shield for the injector return lines

 

[dbrannon79]

Ok got the wire fixed and wrapped the down pipe with some heat wrap I had from another project

tested power to the rest of the glows and all seems good

question... I did a test on timing the glow cycle with the ECT sensor unplugged making the pcm think it’s -40 degrees and all I got was 5 seconds. Same as when it’s connected! Correct me if I’m wrong but I don’t think that’s right!

 

[Jaryd]

Have you tried cycling the glow plugs 3 or 4 times in row before trying to start the truck

 

[MrMarty51]

I’m wondering if the GP controller is getting weak.
A remote starter solenoid works good for a GP over ride, along with a heavy duty push button switch.

 

[dbrannon79]

I have done the screwdriver over the relay thing before and it helped

I’m about to Jerry rig an override in the cab since I know where the yellow trigger wire is behind the glove box the pcm used to energize them

 

[dbrannon79]

Well scratch that one. I double checked the pcm wire to the glow plug relay for a ground feedback after it cycles off and nope not using that wire without a diode to keep voltage from feeding back to the pcm! Glad I checked

 

[dbrannon79]

I’ll just order a starter solenoid and wire it in for an override

I think this glow plug relay has been replaced before from the looks of it. It wouldn’t hurt to replace it with a GM one too. Jut for piece of mind

 

[dbrannon79]

I’m just stumped by the fact that the pcm controls the time duration by the temps and disconnecting the ECT still gets the same 5 seconds

one of the guys at work drives a 6.5 burb and he had told me it should be about 10 seconds on first initial key on.