Cold start issue
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Junior User
Joined: Apr 2012
Posts: 54
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Tugly, any other suggestions? I read through the information from the link on your sig and didn't really find anything else. The truck runs great once started, after started in the morning it starts right up the rest of the day. And it's never really an issue starting it cold like having to crank it over and over and over. Usually just have to give it a little gas for a few seconds then it's fine. Today is started right up at 55 degrees with no hesitation which makes me think the GPR might be going bad since it only reads 10 volts on the right post with KOEO. The truck will start right up if it's plugged in also.
Hotshot
Joined: Jan 2011
Posts: 18,849
Likes: 179
From: Puget Sound
Normal idle when cold is ICP 700 PSI and IPR 14%. Your numbers are a tad high (nothing serious), so I have to ask if any modifications have been done at all. 10K mod? Temperature sensor? Add-on wired in?
This has all the smell of a Glow Plug problem of some sort. You tested each glow plug with the harnesses disconnected? Read the voltage across the GPR main posts while activated. If you get a voltage, this says the contacts are done.
This has all the smell of a Glow Plug problem of some sort. You tested each glow plug with the harnesses disconnected? Read the voltage across the GPR main posts while activated. If you get a voltage, this says the contacts are done.
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Junior User
Joined: Apr 2012
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I just bought this truck a year ago and am not really sure what mods have been done, as far as I know just intake and exhaust. I tested each glow plug through the valve cover harness with my ground on a battery. As far as testing the GPR where should my ground be, is battery fine?
Hotshot
Joined: Jan 2011
Posts: 18,849
Likes: 179
From: Puget Sound
The harness, or the Valve Cover gasket? If you have the harness connected, you will read all of the Glow Plugs in parallel. I suspect you have two bad ones, if you did it with the connector on.
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Junior User
Joined: Apr 2012
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Through the valve cover gasket, how do you test them with the valve covers off? I just replaced all of them with new motorcraft ones about a month ago and it's a huge improvement from what it was.
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Hotshot
Joined: Jan 2011
Posts: 18,849
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From: Puget Sound
When it comes to injectors, the 42-pin connector is easy-access, so that tests every component from the 42-pin to the injector coil and back.
Senior User
Joined: Aug 2012
Posts: 307
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From: thornton CO
Don't know if this will help but I'll offer my .02.
I also fight a cold start issue. I've done all the suggested trouble shooting, new gp's, gpr, and even injector o-rings. I've chalked it up to worn injectors. On a cold start I've checked the exhaust manifolds at each cylinder as the truck warms up and three of them are 60-80 degrees cooler than the rest. If you have a infrared thermometer it's a quick and easy test. FWIW.
I also fight a cold start issue. I've done all the suggested trouble shooting, new gp's, gpr, and even injector o-rings. I've chalked it up to worn injectors. On a cold start I've checked the exhaust manifolds at each cylinder as the truck warms up and three of them are 60-80 degrees cooler than the rest. If you have a infrared thermometer it's a quick and easy test. FWIW.
New User
Joined: Feb 2014
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The reading from either post on the Glow plug relay should be the battery voltage. With a helper perhaps, turn the key on and while the glow plugs should be energized you want to make sure that both posts on the relay measure the same voltage, whatever it may be, and that the voltage reading is what the batteries are reading at the same time. (again, while the glow plugs are energized) The glow plugs are a large drain on the batteries, if the batteries are getting old the voltage reading could be 10 but it should be above 10.5 Low voltage points to spent batteries.
So, in short, cycle the key on when it's all stone cold and work quickly taking measurements(you will have around a minute, up to two if it's really cold). Both sides of the GPR and maybe even battery voltage at the batteries but this should be the same as the constant hot side of the GPR because it is directly wired. The relay is just a set of contacts, but the contacts can burn/corrode and cause less than full voltage to get to the glow plugs.
Also make sure you are measuring at the GPR and not the Intake Air Heater. Do you have two relays? I don't see what truck you have.
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Junior User
Joined: Apr 2012
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My truck is an early 99, I did check the right post of the GPR with the glow plugs enegerized and it reads 10 volts. So based on what your saying the GPR is bad or my batteries are bad? And just one relay
Lead Driver
Joined: Jun 2004
Posts: 6,303
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From: Amarillo, TEXAS!
Did you see this?
With the key on and the glow plugs energized, take voltage readings at both large lugs on the GPR. There should be minimal difference between the two. If the outer lug reads 12 and the inner reads 10, it's probably time for a GPR. If the reading at both lugs drops to 10, it could indicate a bad connection somewhere before the GPR (battery terminal perhaps), or weak batteries.