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‘94 Suburban Stalling w/ Codes

Big T

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18 - Pump cam reference pulse error
35 - Injection pump pulse width error (response time short)
54 - PCM fuel circuit error

Recently replaced lift pump and OPS
 
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need to start with the basics, Check fuel pressure, check for air (clear return line on IP). If both those check good I'd try a different PMD. If still no change I'd test the OS and CPS
 

THEFERMANATOR

FRANKENBURBAN
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There's a good chance the optic sensor is failing with all those codes, or the crank sensor. You can try unplugging the crank sensor and see if it will start, if it still doesn't try plugging the crank back in and un0lug the optic sensor and see if it will start then.
 

Big T

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Did you even check the other things? Sounds like your throwing parts at it.
Did you even check the other things? Sounds like your throwing parts at it.
Already did all of that about 1.5 months ago. Clear line, fuel pressure gauge, lead to my son replacing lift pump and OPS. We know the PMD is good as it's be tested on mine and vice versa. It's not air in the fuel system. Ran great for a month, then this stalling with codes. When I saw the crank reference code, I ordered the CPS. It's behaving like the CPS experiences I've had before. $43 is no big deal and my time is very limited.
 
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Just for an example 3-4 years ago I was working on a 94 for someone. They'd had it into a couple of shops and they just wanted to throw parts at it. The owner of it couldn't afford to have them do that so I took a look at it. It ran really rough,hooked up a scanner to it and no codes. Watched the missed counts for the CPS, showed fine finally I did the OS and CPS test and found out the CPS was the culprit. Might point here is codes or lack thereof don't seem to mean alot with the 6.5. and by the way that particular CPS was a pia to change. Hate to go through all that and then find out it was the OS.
 

Big T

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It will tell you if it's really the CPS or the OS. The code is a somewhat generic code for timing. It could be either. And you should be able to unplug either with out pulling the intake.
For $43 a new CPS will tell whether it's the CPS. If not then it's the OS and we're looking at a new IP, for which we just pull it off the other engine.
 

WarWagon

Well it hits on 7 of 8...
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May as well order the timekeeper to replace the chain and have it on hand when you change the CPS.

Some CPS sensor's don't exactly come out without a fight. First thing is anything you can grip on the old sensor comes off with a brittle plastic "SNAP!" sound followed by blue smoke. Then you drill it and attempt to remove it with a bolt run into it, more blue smoke when the bolt comes free with the CPS still stuck. Finally you remove the entire timing cover and press it out after drilling it clean through to weaken it.
 

Big T

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May as well order the timekeeper to replace the chain and have it on hand when you change the CPS.

Some CPS sensor's don't exactly come out without a fight. First thing is anything you can grip on the old sensor comes off with a brittle plastic "SNAP!" sound followed by blue smoke. Then you drill it and attempt to remove it with a bolt run into it, more blue smoke when the bolt comes free with the CPS still stuck. Finally you remove the entire timing cover and press it out after drilling it clean through to weaken it.
I've seen where a guy placed a steel bar with a hole in it across the CPS and used a bolt to pull it out. Sorta like a puller.

Anyway, on this truck we have no idea as to the relative age of the parts. Truck has 290K miles on the odometer which was not clocking all miles when we got it at 242K miles. I've replaced timing chains before. If I'm in that deep, then a Fluidampner is going on and yes a new timing change.
 

Will L.

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Cps getting stuck in there is exactly why you do the test before replacing it. Well, that and having had new defective sensors from time to time.

Unplugging and starting each way takes like 10 minutes max. Way worth it before swapping parts that sometimes turns into 8 hours of crap for no reason.
 

Big T

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Changed the CPS. Yes it fought coming out, but I ran a drywall screw in it and used a door panel pry tool to lift it out. Did not spend a lot of time on it, but damn that’s a greasy MF’r. Megan Kelly would let me finger bang her.

Did not clear codes, but it started right up. However it misfires above 3200 to 3300 rpm...
 
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Will L.

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No you aren’t. No way I ever change one unless it is proven bad. WarWagon was not exaggerating one bit. Timing covers get damaged once in a great while removing them.

Plus they can be really hard to get to depending on rig and accessory lay out. Some hummers HAVE TO remove the power steering pump.

Glad for BigT he seems to get his out no problem because he is just - No big deal- so cool.
 
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