My 03 , runs awesome when it starts ? if you shut it off it will not start just cranks ? no codes , just cranks over ? little shot of start fluid away it goes ? it will run perfect all day just can't shut it off ? like it loses fuel ? only 80k miles on it
LB7: 03 no start
- Thread starter butch2000
- Start date
I think starting fluid is bad for them, But I could be wrong.. Is the fuel filter housing looseing prime? Any fuel look like its leaking around that area
It is best to avoid starting fluid on the Duramax.
When it is hot, if you pump the primer until it is hard, does it fire right up? If you pump the primer, does it stay hard for 5 minutes if you leave it sit? (It should)
If it isn't losing prime, and it is still hard starting, that means it is probably having a hard time building rail pressure. There are only 3 reasons for this.
#1, the most likely, is the injectors are on the way out
#2 is the CP3 is failing
#3 is the rail pressure relief valve is leaking. This is very rare on the LB7s.
When it is hot, if you pump the primer until it is hard, does it fire right up? If you pump the primer, does it stay hard for 5 minutes if you leave it sit? (It should)
If it isn't losing prime, and it is still hard starting, that means it is probably having a hard time building rail pressure. There are only 3 reasons for this.
#1, the most likely, is the injectors are on the way out
#2 is the CP3 is failing
#3 is the rail pressure relief valve is leaking. This is very rare on the LB7s.
if I use pump the primer , it builds up hard to push the primer , then all of a sudden it goes easy , ?? like the fuel is gone ,? is there a kit or seals in the primer that can be replaced ?
There's a kit for rebuilding the filter head available from several supporting vendors.
desired is 40 , act is 3 ? Just scanned it and has code P1094 low rail , fpr idle is at 16-17 first start cold , settles at 10-14 after running a few minutes , Fuel rate MM3 cranking over is 62-44
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There is a rebuild kit you can get. Henry (Creatures of the Night Performance) sells one for $62. However, that only will fix your problem if it is the filter head that is leaking. When it goes soft, that means it is leaking somewhere. Look around the lines, and see if you can find a leak.
To measure return rates, it involves taking the engine part way apart. It is a bit of a pain. It is usually best to eliminate fuel/air leaks before doing a return test.
To start, the truck must build at least 10MPa (1,450 PSI) of rail pressure. If it doesn't build that high, it will not fire the injectors. So when you measure the actual rail pressure on a scan tool, look for this value when cranking.
This is sounding more and more like failed injectors. Sorry
The idle FRP should be 30-50 MPa, depending on coolant temperature. Idling at 10-14 MPa is way low. Like barely running.
ok , I will check cranking rail pressure , truck only has 70,000 miles on it that is why I was not thinking injectors ? oil is super clean , right level etc
Just for shits and giggles, unscrew your bleeder screw on the fuel filter housing and make sure there is a little O ring on it. That little o ring caused me a lot of headaches a while back
is there anyway to narrow down which injectors are the bad ones ? or which ones are giving the high return ?
It is theoretically possible, but extremely unlikely. It would have had to stick closed, which normally takes a lot of power.
If you really want to find out, you can swap it out, but don't get your hopes up that it will fix anything.
And sadly, 70k miles on a set of LB7 injectors isn't unheard of. My last set only lasted 60k before they were starting to annoy me. The first set lasted 200k, though, so???