runs but will not restart

[max3208]

I am new here was wondering if I can ask a question maybe someone will know....I just put on a new primer on my truck and the only way my motor runs is by either to start up and I'll run it for 20 mins or so and then turn it off and restart it and it will not start on its own....I have no leaks in my fuel lines....the motor has been stored in doors while i was building this truck for 2 years. It runs good no smoke no making oil strong motor with about 150,000 on the motor its a Lb7 02...
If any one could help that would be great...thanks

 

[Ne-max]

Weak cp3 or a bad injector.

 

[Aaron@LDS]

No air in the system... That usually means injectors are returning too much fuel to start. Do you have any way to watch rail pressure?

You can also do a return rate test but it's labor intensive.

 

[max3208]

No air in the system... That usually means injectors are returning too much fuel to start. Do you have any way to watch rail pressure?

You can also do a return rate test but it's labor intensive.

no air in the system...I fixed the leaks I had....I do have a PPE HOT ET programmer it does have diagnostic on it so I can see things. do you have something in mind ? as to the rate of flow how do you do that ? thanks

 

[max3208]

I took the return valve and it was clean of rust answer threw in the shims for the spring and ran it but still won't start on its own...i guess pull the pump? it runs great when its started anybody have thoughts ?

 

[Texas Chevy]

When you get it to start and then shut it off does it lose its prime

 

[max3208]

Not that i can tell....the primer is firm when i checked it.

 

[x MadMAX DIESEL]

Sounds like a clogged filter and or air in the fuel

 

[max3208]

I replaced the filter and it has a new top kick primer. I can check my fuel line again.
Does any body know about main injector ? I was looking on my programmer and at idle it says -3 main injector . are they talking about the pump?

 

[x MadMAX DIESEL]

Is that timing your looking at? They have a main injection quantity but it won't be negative I bet that's timing your looking at.

 

[JoshH]

Weak cp3 or a bad injector.

This is my guess as well. I'm betting it's injectors.

 

[max3208]

This is my guess as well. I'm betting it's injectors.

I have a PPE HOT ET TUNER i was just looking threw it and i noticed the main injector at 3- at idle . i wish i could post photo's of it.

 

[Big Block 88]

This is my guess as well. I'm betting it's injectors.

X2

 

[Ne-max]

Here is what happens. With cranking your engine without either your cp3 is not spinning fast enough to build enough rail pressure to start. Once hit with either it gives it that jump it needs to build up rail pressure to keep engine running. So the issue is either your cp3 is weak and cannot meet commanded rail pressure while cranking or your injectors are returning so much fuel it will not allow your cp3 to build up the pressure needed. Usually its the injectors returning to much fuel.

 

[max3208]

Here is what happens. With cranking your engine without either your cp3 is not spinning fast enough to build enough rail pressure to start. Once hit with either it gives it that jump it needs to build up rail pressure to keep engine running. So the issue is either your cp3 is weak and cannot meet commanded rail pressure while cranking or your injectors are returning so much fuel it will not allow your cp3 to build up the pressure needed. Usually its the injectors returning to much fuel.

I pulled my return valve out to see if it had any crap in it and it was clean so I put 2 4mm washers in behind the spring so the pressure would be higher on the rail. After running the motor and taking it for a drive I turned it off and restarted it just did the same thing again would not start on its own. I guess now I need to check the pressure on the cp3. thank you for the info

 

[JoshH]

I pulled my return valve out to see if it had any crap in it and it was clean so I put 2 4mm washers in behind the spring so the pressure would be higher on the rail. After running the motor and taking it for a drive I turned it off and restarted it just did the same thing again would not start on its own. I guess now I need to check the pressure on the cp3. thank you for the info

The injectors returning too much fuel has nothing to do with shimming the valve. You need to do a return rate test on the injectors.

 

[max3208]

The injectors returning too much fuel has nothing to do with shimming the valve. You need to do a return rate test on the injectors.

Its sounding more like i Will be doing the test on the injector's . i guess that's what happens when the motor sit for 3 years. thanks for the info

 

[max3208]

ok update ! I have replaced all injectors and replaced the CP3 as well with new. I also replaced all rubber fuel lines with new factory ones. The motor still does NOT start on its own. This is turning into replacing parts and its not fixing the problem of being able to just turning the key on and starting on its own. Every time I do something I think will cure the problem and it does NOT FIX IT ...... Anyone have any ideas !!?

 

[Harbin_22]

Sounds like you need to do better diagnostics. At least need to be able to watch RP while cranking.