LB7: ‘03 No Start Without A Little Help

[LBZ]

Have a chance to buy an unmolested ‘03 ECSB for cheap. 260,000km on it. No idea if injectors have ever been done. Has a brand new cp3. Runs fine with supposedly no haze or anything but it’s hard to start. But just a tiny puff of wd40 and buddy says it fires right up. He’s thinking injectors but I’m not so sure as the no haze at idle thing.

What are the chances it’s not injectors? I’ll have to do all the tests to rule them out obviously if I buy it. Just looking for opinions from the LB7 crowd.

 

[Dukchunter]

I wouldn't touch it without a compression test... needing wd throws a red flag up to me for low compression. Just my 2 cents

I would also be checking for blowby out of the oil filler neck.

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[LBZ]

It fires right up after you shut it off and wait a couple minutes. It’s only after it sits for longer than 30min or so that it has issues. And like I said, no haze.

 

[2004LB7]

Being that it starts up after being off for a few minutes I would say it is a miner fuel line leak, maybe at the filter head.

If it was always hard I would guess high return on injectors.

If I needed a truck, what you discribed wouldn't scare me and I would get it

 

[Dukchunter]

Once warm things expand and can cause higher compression therfore a starting easier while warm... can also check to make sure the fuel system is staying primed... could be losing prime over time also. Starting with wd may get it running to get the fuel system reprimed... alot of variables here. I would get compression number though before anything

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[LBZ]

Being that it starts up after being off for a few minutes I would say it is a miner fuel line leak, maybe at the filter head.

If it was always hard I would guess high return on injectors.

If I needed a truck, what you discribed wouldn't scare me and I would get it

Kinda what I was thinking and hoping. It is a 15y/o unmolested truck so it could be anything from the pickup pos hose in the tank to a bad o-ring somewhere inline to a leaking filter head. Gonna give buddy a deposit on it tonight and then go give it a once over next week when I’m off work and potentially buy it.

Again it’s the no haze thing that has me believing it’s not injectors or bent rods. I guess I will find out.

 

[Dukchunter]

Prime it up using the primer on top of the filter housing. If it's a priming issue the prime should get hard and truck should start fairly easy

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[TheBac]

Dale, it sounds like a slight air leak in the fuel system. Nothing more.

 

[LBZ]

Well I’m picking it up Monday and trailering it home. Hopefully I got it figured by the end of the week. I’m hoping it’s something simple and dumb. Supposedly the guy that owned it before that did the cp3 may have done a bunch of tests including running clear fuel hose looking for air and bypassing the fuel filter but I dunno what kind of quality or workmanship went into these tests so I’m going to start off with the basics. Hell it may even have two o rings on the fuel filter base or something dumb like that for all I know.

 

[LBZ]

So got the truck home. As mentioned it runs pretty good no haze but shut it off and immediately try to restart it and nothing. Tried to log it and balance rates wouldn’t work and then nothing would work. Tried to read the tune and that wouldn’t work so tomorrow when I get home from work I’m going to dig into it some more.

Turns out it’s not exactly unmolested as I did notice the factory filter has been deleted and it has an air dog so I’m going to see if I can find a stock filter head as I want the pump for my lml.

 

[Brent@LDS]

What is your actual vs desired Fuel rail pressure while cranking?

 

[LBZ]

FRP actual is 6.3mpa
Desired is 43mpa

 

[LBZ]

Finally got it to bbx log.
At idle cold
Actual vs desired rp are both at 42mpa
Bal rates were all between -1 and +2 except for two cylinders that were -3.6 and plus 3.9.
After running for a couple minutes all the bal rates went to 0mm3.
Shut it off and it had a a 3 second crank and rp went up to 7.6 and it started.

In park bal rates 1-8
-1.5
2.8
-2.9
2.7
2.0
-2.3
-2.6
2.9

 

[LBZ]

After letting it warm up a bit sit for a couple min then crank it won’t get above 6.8mpa actual frp. RP is too low. Time to do some return rate testing.

Still can’t read the ecm or get my 7.5 scantool to work though.

 

[TheBac]

Well, if the filter was deleted, then I stand corrected.

 

[torqued2dmax]

How much fuel pressure are you getting from your Air Dog to your cp3 ?

 

[2004LB7]

I wonder if the lift pump was a bandaid for return rates getting a little high. Then when they exceeded that it wouldn't start until the rpms where high enough, thus the use of WD40

What are your cranking rpms? Does it help if you unplug the pressure regulator?

 

[Chevy1925]

whats the main injection rate while at idle?

 

[LBZ]

How much fuel pressure are you getting from your Air Dog to your cp3 ?

Not sure. Need to put a gauge in it yet. It has clear fuel hose on the line between the ficm and the cp3 with no air in it if that means anything. You can hear the pump build pressure though.

 

[ikeG]

I wonder if the lift pump was a bandaid for return rates getting a little high.

There is a shop local to me that is famous for this. Seems like he has his customers jump for the lift pump band aid pretty quick when they hear the price difference of that vs. injector replacement.