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Mike K
Guest
3/30/2004 20:32:43
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 Subject: 6.5L cold start
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I have 1994 Chev 3/4 w 6.5L Turbo. The engine is NEW, along with the pump/PMD, lift pump and glow plugs/injectors. This engine is still a serious pain in the neck to get started when cold. When I turn the key on, I DO NOT hear the lift pump running. After I have cranked about 20 time, and shut the key off, the lift pump fires. Crank it another 10-20 then finally starts and throws a lot of blue smoke, which clears up in about 2 min of idleing. Once hot, always lights right off. What is going on with this thing?
 
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pup
Guest
3/31/2004 01:26:32
| RE: 6.5L cold start
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Are your glow plugs working?
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Mike K
Guest
3/31/2004 10:23:38
| RE: 6.5L cold start
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Yes, the glow plugs and controller were both tested and they are all working properly. The only thing I can think of is the fuel pump relay, but I replaced that. However, when I turn the key on, I still do not here the pump spin up. Here's a question; is it the lift pump or the stepper motor that primes the engine for a cold start?
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Mike K
Guest
3/31/2004 23:06:56
| RE: 6.5L cold start
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yes the glow plugs are working. that's the first thing I had tested and they all test fine, including the controller. I have now replaced the fuel pump relay, because when I turned the key on the lift pump was not spinning up. Even with the new relay installed, the lift pump does not spin up. Could this be an oil pressure switch problem? My oil pressure gauge always seems to be reading lower than actual pressure.
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pup
Guest
4/01/2004 04:09:38
| RE: 6.5L cold start
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Message:
I think your lift pump {frame mounted} acts as a
two speed. When you turn the key and oil pressure is at 0 or close to it, it is in low. When
oil pressure comes up after start up it should
switch to high.
I have the same low pressure on factory gauge
you speak of. I have installed a aux. mech.
gauge to see true pressure and it leads me to
buying another electric pressure sending unit
I may try the ops unit I keep hearing about on
this site, but I haven't heard why they are to be better than stock?
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Mike K
Guest
4/05/2004 15:39:04
| RE: 6.5L cold start
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I fixed the problem...I wired directly from the battery to the lift pump, and installed a toggle switch on the dashboard. Now when I go to start the truck when it's cold: I hit the switch, run the lift pump for approx 30 seconds, then light the glow plugs with the pump still running. When the glow plug light goes out, I hit the key and she starts right up! I guess I must have a fried wire in the relay circuit somewhere...
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GmDieselTech
Guest
4/05/2004 16:02:20
| RE: 6.5L cold start
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What you have done though is also bypass the OPS(oil pressure switch) which is a Federally Mandated SAFETY feature, so you do not fuel a fire in an accident, i relaize you have it on a manual switch but you can forget to turn it off or someone else may drive your truck.
Bypassing that it as you did is illegal for good reason because it is VERY DANGEROUS, and you open yourself up to a lot of liability, especially now after publicly stating what you did... you need to correct the problem,
find the problem in the relay circuit and correct it.
Are you getting fuel psi and flow after you get it running?
Or is the injection pump sucking the fuel?
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Happy Motoring-David
GmDieselTech@Yahoo.com
Administrator at Yahoo Autos Groups 'ChevyGmcDiesels"
http://autos.groups.yahoo.com/group/chevygmcdiesels/
Moderator at Diesel Doctor
http://www.dieseldoctor.com
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Doc
Guest
4/08/2004 12:53:44
| RE: 6.5L cold start
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<This post was updated by DIESELDR. 4/08/2004 14:58:48>
EDITED.
HARASSING TROLL POST REMOVED
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Mike K
Guest
4/08/2004 13:49:15
| RE: 6.5L cold start
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Message:
Hey GMDieselTech; What you say makes alot of sense. Hey Doc, lay off--that's something I never really thought about. Could it be a bad OPS Switch that is causing this problem? It seems like aside from the manual bypass, the pump only seems to want to run when it feels like it. The one exception is when the truck is already running.
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GmDieselTech
Guest
4/08/2004 15:02:28
| RE: 6.5L cold start
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Message:
ops takes over once there is oil psi, but you may want to change it just because they do tend to fail often.
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