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Discussion Starter · #1 ·
Hey i have a 94 GMC 6.5 non turbo with 282k kilometers and ever since i bought it it has started poorly. It takes about 5-7 seconds of cranking before it starts, every single time but after that much cranking it fire up beautifully. if you re-start it, hot or cold within 30 seconds to a minute after it has been running it will fire right up. but if it sits for a couple minutes or more it has to crank it's 5-7 before it fires up.... i changed and checked all the glowplugs and it made no difference at all.... the temperature of the air outside has no effect on the starting either nor the temperature of the motor. the glowplugs cycle how they should, around 10 seconds on cold startup an temperature appropriate the rest of the time so i'v pretty much eliminated the glow plugs. i initially thought maybe the lift pumps prime circuit was missing when the key was turned on so the lift pump wasnt engaged untill the OPS sensed oil pressure but read in a thread that it doesnt have a prime circuit in that year. i also did the lift pump tests an theres plenty of pressure. i also tried another Fuel driver and there was also no change... i have no codes but have access to a mac mentor scan tool to read all the parameters if need be. i have no access to a manual to read up on anything so i'm pretty lost at this point so any help at all from anyone would be awesome thanks!
 

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I had a ford 7.3 IDI that did exactly the same thing. In my case, it was a leak down in the injection system. Every time I tried to start, it had to draw the fuel up. The longer it sat, the worse it was.
 

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On your next cold start turn the key to the "On" position, but don't start the truck, move gear selector to "D" then turn key to "Start" position. When you do this the lift pump should run. Run pump for a few seconds then move gear selector to "P" and start the truck as normal. Doing this will eliminate the possibility of the leakdown Edgewater mentioned.
 

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Discussion Starter · #5 ·
hey, my glow plugs are fast heating ones i forget the brand, i got them off ebay and had then in my 6.2 for a year and a half an they would start that puppy in -20 not plugged in. i tested them all before i put them in with a battery and once installed i tested them with an omh meter an they all tested under 2 ohm....they were anywhere from 0.3-0.5. and i tryed makin the ignition go in drive but theres an ignition detent that doesnt let me even turn the key. so i just jumped the pump at the fuse to the junction block that sits right beside it to build some pressure. and what do you know she fired up in like 3-4 seconds, way quicker then before but still not as fast as a normal diesel...so how would a guy check for leak back an how does that system work?
 

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That sounds like my 94, I wish I could figure mine out also. Good thing I live in texas or it would never start up there.
 

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On your next cold start turn the key to the "On" position, but don't start the truck, move gear selector to "D" then turn key to "Start" position. When you do this the lift pump should run. Run pump for a few seconds then move gear selector to "P" and start the truck as normal. Doing this will eliminate the possibility of the leakdown Edgewater mentioned.
I have a 5 speed in my 94 3500, would leaving the clutch out and trying to start it do the same thing as leaving it it "Drive"? It has a lockout that won't let the engine turnover unless the clutch is depressed.
 

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Don't know for sure, but it is easy to try.
 

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Any codes stored?

Check LP as mentioned....OS filter harness still in place?
 

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Folks don't guess at what it might be;

Corolla pointed him to the proper diagnostic thread lets see results of diagnostics
 

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I have the exact same truck with the same problems. I tried chasing the problem with batteries,starter,glowplugs,pmd,glowplug terminals, with no change whatsoever in the crank time. Finally changed injectors and the difference is night and day. The truck now starts instantly even in cold weather.
 

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My 94 does the same thing,. could it be a '94' year specific thing? different programming? i have the 'f' engine with the 94 only IP,
it seems this problem was exacerbated when i put in the free hand me down chip i got for it,..
nick
 

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Discussion Starter · #13 ·
I have the exact same truck with the same problems. I tried chasing the problem with batteries,starter,glowplugs,pmd,glowplug terminals, with no change whatsoever in the crank time. Finally changed injectors and the difference is night and day. The truck now starts instantly even in cold weather.
well thats interesting because i was palnning on changing the injectors anyways cause there is also a random knock that i guessed was an worn out injector but didnt think that would be related but it sure could be. well i'll get them ordered right away then to eliminate that possibility an see where that leaves me.
 

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It is a good "maintenance" item to change the injectors... but don't just go changing parts without doing the diagnostics first. An item like that is a step in the right direction, but don't need to go easter eggin' parts changing for no good reason either.
 

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mine does the same thing, i just put in new batteries, fixed all grounds, checked all the glowplugs, and cleaned and tightened the connections. It started a little strong but was still slow to crank. My cousin did a load test on it at his shop and he said the starter is drawing quite a high current which can mean a bad starter. I looked under for the connections and they looked like they were on top and i would have to remove the starter to make sure they are not loose.
 

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Discussion Starter · #16 ·
mine does the same thing, i just put in new batteries, fixed all grounds, checked all the glowplugs, and cleaned and tightened the connections. It started a little strong but was still slow to crank. My cousin did a load test on it at his shop and he said the starter is drawing quite a high current which can mean a bad starter. I looked under for the connections and they looked like they were on top and i would have to remove the starter to make sure they are not loose.
yeah i'v already changed the started casue it was draggin from the guy before me crankin it so much. so it turns over really fast an proper but just takes forever to fire... your starter is probably gone, when my burban's starter went it was drawin 400 amps when cold starting and one battery could hardly even turn it over. my dads gonna be pickin my injectors up in the states early next week so i'll have an answer to my problem in a week or so
 

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Discussion Starter · #17 ·
well im a little slow gettin back at you all with an update but i change the injectors and found one to be leaking. i guess that was enough to lose the fuel in the line and flood it or something. but it solved all my problems, the hard starting is fixed and the random knock is healed. And i recently put on a cowl hood, led smoke tail lights and 3rd brake light, chrome door an tailgate handles and 2 alpine typeS 12's... shes commin along thanks for all your help everyone!
 

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My dads 94 6.5 has been doing exactly what you guys have been saying, hard starting, crank forever but start after about 20 sec if you let the starter off at just the right time. I have been going through the checklist on my own when I am at home. I pretty much have it down to the injectors. 365,000kms on them. Just curious as to recommended change intervals if any? Sorry I don't mean to hijack the thread. I will post the checklist at some point.
 

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My dads 94 6.5 has been doing exactly what you guys have been saying, hard starting, crank forever but start after about 20 sec if you let the starter off at just the right time. I have been going through the checklist on my own when I am at home. I pretty much have it down to the injectors. 365,000kms on them. Just curious as to recommended change intervals if any? Sorry I don't mean to hijack the thread. I will post the checklist at some point.
Answered a amillion times in faq's and in search threads, but for 1,000,001 recommended interval changing for Injectors is at 100,000 miles.
 
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