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‘94 Suburban Stalling w/ Codes

Will L.

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If you had some time to waste on it, the old vacuum measure trick might reveal floating valves, but that takes some time and might make enough smoke neighbors might think you started another fire there.

You hook up a vacuum gauge to the intake and undo the air feed from the turbo so it is running natural aspiration. Then watch the vacuum gauge for fluttering to indicate. This really is done on gas engines, but will work to a lesser degree on n/a diesel also. Oh heah, you have to rig an airfilter in to cause restriction of air flow.
 

Big T

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Home from Montana and my son Colby came over with our granddaughter Monet (aka MoMo) to give us our Xmas presents.

Despite the post surgical foot complaints, I joined Colby to do some tests on the Suburban. We were eventually able to get it to light, but briefly and it died. Most of the time it’s lots of cranking with occasional catch. We unplugged the OS (if it’s the plug on top of the IP) and no difference. Have not installed a clear hose on the return line and will try that later today.

Looks increasingly like this IP is done.

Would the IP from our ‘95 engine work on this ‘94? What do we look for to verify applicability?
 

Big T

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The IP's ID tag is on the back (of course) above the outputs (whateverthehellthey'rereallycalled). You'll need, or more to the point, Colby will need a mirror and the Upper Intake off to see it.
View attachment 55189
Using a mirrror and translating backwards, I believe the top row on the ‘94 IP reads: D24 831-5521. Could not read the lower row, but it seemed more like a serial #.
 

Big T

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So we'll be taking on this project to change the IP in about 2 months and I'm planning phase. Should we also change out timing chain, timing gear, Harmonic Balancer and Pulley while we're in the front of the engine. Looking for a list of parts we should change. As this is already a 300K mile engine, we are not looking to upgrades like Fluidamper, or Phaser Timing gear set. Just stock stuff to try to get another 100K out of this engine.
 

Will L.

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Then I would say:
cloyes chain no gears unless you see damage or bad wear, ac delco balancer and drive pulley, front main seal- several food ones out there. Seriously consider a new waterpump because if it goes soon afterwards, you’ll wanna kick yourself. AC Delco on that too. New serp belt. Since no time keeper set- dont bother buying gaskets- just 1 tube of permatex the right stuff for all those surfaces.

Feel the power steering pump out just because it is easier then too- if it leaks or has acted up any, now is the time.

I don’t like installing new injectors at the same exact time as a pump- because if there is a problem - diagnostics is muddied. But after you do the ip, and all is good for a week- then I drop in the new ones. I have only seen that be an issue a couple times out of hundreds, so if it’s all or nothing then do it at same time. The guys that got the new India Bosch’s from Leroy that had them tested said they were within the best spec range of 25psi so get them. Keep your old ones as spares between the two rigs. Rembember ‘working’ injectors dont mean full mpg injectors and they have a 100,000 mile lifespan anyways.

And you know I am gonna say: Fuel pressure gauge measured at the ip inlet. The rubber fuel line should be sae30r9 and start out with the clear line on the ip return.
 

WarWagon

Well it hits on 7 of 8...
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Just change the pump. Seriously it's every single bolt and nut on the front of the engine and for what? Another krap chain that's going to streach back out in 30K miles. Oil and coolant leaks are a real risk to this job.

@Paveltolz is bang on as I went through this gear swap only to discover my engine was scrap metal. So if it has good compression either leave it alone or put the gears in it. Who says it only has 100k left? Use the gears on the next engine like I am.

Chains are for krap you are slamming back together to sell.

Is this the high blowby engine? If so, again, compression test...
 

Big T

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Just change the pump. Seriously it's every single bolt and nut on the front of the engine and for what? Another krap chain that's going to streach back out in 30K miles. Oil and coolant leaks are a real risk to this job.

@Paveltolz is bang on as I went through this gear swap only to discover my engine was scrap metal. So if it has good compression either leave it alone or put the gears in it. Who says it only has 100k left? Use the gears on the next engine like I am.

Chains are for krap you are slamming back together to sell.

Is this the high blowby engine? If so, again, compression test...
Chain is most likely the original and it has gone 290K miles. You seem to be a small minority who has issues with chains. Then again, you seem to always have issues and have grenaded more engines and peripherals than anyone here, passing it off as faulty parts and what not. Then there are the rest of us who seem to have decent success, including success with aftermarket parts.

So how do you do a compression test? Through the injector holes or glow plug holes?
 

WarWagon

Well it hits on 7 of 8...
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@Big T my luck has nothing to do with GM low designed life to be cheap. The chain streaches due to the IP shock loading. My luck has allowed me to inspect the new timing chains at 30k miles and it's so sloppy that I am sincere in saying put gears in it or don't waste your time. A new chain will require retimed in short amount of miles and soon back at near same streach. GM allowes 0.8" of slop and that should make it's weakness clear.

It's a lot of trouble to get to the chain so make it worth the trouble. :woot:

Compression test can be done through glow plugs or injector holes. Driver side glows, passinger injector holes. Cheap tool set has both adapters - in fact you can borrow mine.
 
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