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Discussion Starter · #1 · (Edited)
I just replaced all injectors in my 2003 lb7. I took my time with everything and made sure all bolts were torqued to spec. I replaced all the banjo crush washers including the 2 for the ficm. I was so excited to get her fired up after a couple weeks of it sitting(did most of the work on weekdays after work). Opened bleeder screw, turned ignition for airdog to prime. Sprayed fuel everywhere, tightened screw, cranked for 10 secs. Loosened screw and primed it at the housing. Cranked again. Got it to start for less than a second and it just does the same thing everytime. It cranks for a few seconds then starts and dies in less than a second. I put a test light to glow plugs after turning key on. they have power for a few seconds then the light shuts off. That's how it should be right? Also I know I have plenty of fuel. But it sure seems like there's zero fuel. Please help me. Please!
 

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Welcome to DieselPlace

Please tell us more about the vehicle ( Make, Model ) and list all mods

(y)
 

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Discussion Starter · #3 · (Edited)
It's a 2003 gmc lb7 duramax. I just have the airdog 2 4g 100 gph lift pump and a sinister diesel cat fuel filter adapter. I had had diablosport tuner hooked up to it like a year ago, one that plugged in to the obd2. My cousin put the 100 hp performance tune on it. I borrowed that tuner back from him to remove the tune because I felt like it was actually having less power but it wouldn't let me!.. I think the tuner was saying my vehicle is not supported or something similar.

I just don't get it! Everything was labeled and put back together exactly as it was! I tried it again this morning. It cranked for 4 or 5 seconds, then as soon as it starts it dies. Could it be because the batteries were unplugged for a couple weeks? Idk a security thing maybe? When I turn the key, after a few seconds the security light shuts off so maybe not. I just want to pull the camper this year.

Thanks for any help in fixing
 

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Discussion Starter · #4 ·
So far I've replaced fuel filter, primed all air out with key on for lift pump to push and after fuel spray I tightened, then cranked. Did this several times. No air comes out the bleeder adter the first time I primed it. Got under and primed the lift pump filter just in case. I checked all lines. Idk. The blinking red light at the stereo blinks all the time. Even when I'm in the car, doors unlocked. That's the security right? Somehow I think the truck is locked for starting because it's like a half start when it starts. I mean you hear it start but for a split second. Maybe a half second
 

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Discussion Starter · #5 ·
My key fob doesn't work.. hasn't since way before the injector change tho. Could that effect starting an 03? I know the batteries have not been unplugged since before the fob went bad.. and the batteries were disconnected for 2 weeks during this injector install. Everytime I try to start it, after it goes poof and makes me think it started, the car with key light turns on the dash for a second or 2 and shuts off.

I'll keep you updated, thanks for any clues to fixing this
 

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My key fob doesn't work.. hasn't since way before the injector change tho. Could that effect starting an 03? I know the batteries have not been unplugged since before the fob went bad.. and the batteries were disconnected for 2 weeks during this injector install. Everytime I try to start it, after it goes poof and makes me think it started, the car with key light turns on the dash for a second or 2 and shuts off.

I'll keep you updated, thanks for any clues to fixing this
If you think it may be a VATS issue then you can perform a relearn to see if things improve: GM Computer Relearn Procedure - LS1TECH - Camaro and Firebird Forum Discussion
 

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Discussion Starter · #7 ·
Hey Dually, thanks for that. Do you think I can do a relearn even if my security light is not on constantly? I only see it pop on after trying to start the truck. Everyone is saying when you put the key in the ignition, the security light should stay on for 10 mins and shut off, but mine does not.

Thanks
 

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Hey Dually, thanks for that. Do you think I can do a relearn even if my security light is not on constantly? I only see it pop on after trying to start the truck. Everyone is saying when you put the key in the ignition, the security light should stay on for 10 mins and shut off, but mine does not.

Thanks
Hard to say. The VATS can be finicky in some vehicles.
I would also double-check all fuel lines, return lines, etc. for any kinks, cracked hose, etc.
 

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Discussion Starter · #9 ·
No kinks or cracks. I cant hear or see anything leaking. After work im going to go buy a cheap $50 scanner from oreillys and see if it tells me anything. To check my fuel rail pressure, do i just need to buy a gauge and connect it to the shrader valve by the alternator?

Thanks
 

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Discussion Starter · #10 ·
It really helps having someone to help you with this stuff. My brother was over so I had him crank it over0 while I watched on the passengers side by the filter. He cranked and I saw fuel squirt from the number 5 pressure line on the rail. Tightened it up to 30 ft lbs and had him crank again. It tries to start faster now. Cranks only a second or 2 before going poof. Better than the 5 seconds of cranking before. I'm gonna tear the passengers side hosing and crap off tmw and see if I just forgot to torque more lines over there. 🙃
 

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Discussion Starter · #11 ·
no codes.

Got the lines tightened on the passengers side. It was only the cylinder 5 leaking fuel from the rail on pressure line, the rest were torqued. Truck still just cranks and does a half start right away then shuts off. My batteries are pretty much dead. I've been jumping it when it won't crank. So desperate to figure this out. When hooked up to another vehicle of course it cranks fine. Would the batteries being charged make any difference? I mean it seems like it has to be a fuel problem. My buddy hooked it up to his snap on scanner. No codes except an old glowplug relay one that was there before and I replaced 2 years ago.

Could I get a fitting for the Schrader valve to plug my air compressor to and set it to whatever psi and spray soapy water on the lines to check for leaks? Would the FPR be a possibility? I may just throw some cheap parts at it. I really just don't want to bend over and have it towed to shop. I used 50% ether starting fluid and it started all clankity like for 2 or 3 seconds. I won't do that again. Sounded like the engine begging for mercy. What else can I check?

Thanks
 

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no codes.

Got the lines tightened on the passengers side. It was only the cylinder 5 leaking fuel from the rail on pressure line, the rest were torqued. Truck still just cranks and does a half start right away then shuts off. My batteries are pretty much dead. I've been jumping it when it won't crank. So desperate to figure this out. When hooked up to another vehicle of course it cranks fine. Would the batteries being charged make any difference? I mean it seems like it has to be a fuel problem. My buddy hooked it up to his snap on scanner. No codes except an old glowplug relay one that was there before and I replaced 2 years ago.

Could I get a fitting for the Schrader valve to plug my air compressor to and set it to whatever psi and spray soapy water on the lines to check for leaks? Would the FPR be a possibility? I may just throw some cheap parts at it. I really just don't want to bend over and have it towed to shop. I used 50% ether starting fluid and it started all clankity like for 2 or 3 seconds. I won't do that again. Sounded like the engine begging for mercy. What else can I check?

Thanks
Batteries make a BIG difference..
Remove your batteries and take them down to your local auto parts store and ask them to individually load test them.
If one or both fail the load test then replace them both as a matched set.

You need the appropriate cranking amps to get the motor fired up.
 
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Discussion Starter · #13 ·
so even though it cranks hard and fires up before it dies while being jumped, That could still potentially be why it dies right away? I mean on a gas burner, when i have a dead battery, i can be jumped and it will start. can I just charge them at home and check with a voltmeter or will the load test check more?

Thanks
 

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so even though it cranks hard and fires up before it dies while being jumped, That could still potentially be why it dies right away? I mean on a gas burner, when i have a dead battery, i can be jumped and it will start. can I just charge them at home and check with a voltmeter or will the load test check more?

Thanks
You mentioned above:
My batteries are pretty much dead. I've been jumping it when it won't crank.
If your batteries are not up to the task, you'll have problems.
A diesel engine needs to spin over fast enough to create the heat for combustion to occur. A gasoline engine only needs a spark.
A voltage test of the batteries is only one way to check a battery. A load test checks the condition of the cells of the battery which provides the amperage needed to crank the engine over.
Not enough cranking amps= not enough to spin the motor over fast enough to properly start.

A load test is an important check for a diesel engine battery
 

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Discussion Starter · #15 ·
I will get them as charged as I can and take them in for the load test. I've also been told to take off my ficm and clean it/ dry it. What should I use to clean it?

Thanks
 

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I will get them as charged as I can and take them in for the load test. I've also been told to take off my ficm and clean it/ dry it. What should I use to clean it?

Thanks
Only use electronics cleaner on the pins of the connectors. You should be able to find it at any local auto parts store.
 

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Discussion Starter · #17 ·
OK so my buddy hooked up his snap on again. We cranked it over and it's getting between 5500 and 8800 psi over the 4 or 5 times he cranked. And it read 204 psi with the key turned and airdog running. So now I'm wondering where to go next after this ficm is cleaned and dried

Thanks
 

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Discussion Starter · #18 ·
I took the ficm apart very carefully. It looked dry and brand new inside. I took a hair dryer to it for a few mins just in case. Got all that put back together and cleaned the contacts with electrical cleaner and blew them out. No electrical wires under the hood seem broken in any way. I'll see if I can get a relay tester so I know for sure they are tested right! Now it cranks and starts instantly.. but still dies instantly. I'm so sick of working on this until bedtime! Maybe tmw is the day
 

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We did injectors on an 04 LB7 a few years back. When everything was back together, connected batteries, it would not start. So, disconnected again and reconnected, it only ran on 4 cyl. Disconnected batteries again for 10 minutes and this time reconnected in different order and ran on all 8. So apparently it makes a difference to the FICAM as to which terminal is connected first, sorry, can't remember which to connect first. GM tech (friend) had the truck for 3 days and couldn't get it to run. When we told him about the hooking the batteries in a particular order(either positive first or negative first, sorry forgotten order) he said GM specs don't mention that.
Not saying this will cure your problem but you might try it.
 

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Discussion Starter · #20 ·
I have my batteries getting load tested right now. Im gonna pick em up in a few hours if good and maybe try looking for a air leak on the low pressure side? from the filter back to the tank. Will it help to prime the filter housing still and spray some soapy water all over the rubber lines?

Could Fuel pressure regulator be bad and not show any codes? If I have enough rail pressure, then it has to be a leak on the low side or something electrical right?

Thanks
 
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