Crank no start intake vapor!

Pumper

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I have a 1992 7.3 idi nonturbo has sat for a year new batteries, starter and changed to facet fuel pump! when I go to start vapor coming back through the intake! Help!
 

rreegg

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Have seen a similar thing on a 2cyl Volvo diesel, OHV. The difference is the Volvo has a decompression lever that “lifts” the valves or something, when starting the engine with the valves lifted sometimes some exhaust gas will release out the air intake.

my first instinct would be to check the 7.3 valves and see if any are stuck or similar. Maybe someone who’s more experienced can chime in and vet this idea
 

Pumper

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Thanks, I took one of the valve covers off and they seem to be moving! I was wondering if it could be the rings?
 

Clb

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Dang it Verizon ..
Try feeding a mist of fuel as you crank it over.
It may be a stuck or burnt valve, however if it ran fine when parked I'm thinking stuck valve at worst, which you can see with the covers off but if you bent one already.....
Oh and


Sorry guys I Hadda do it...:p
 

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rreegg

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would checking compression help narrow down things? Honest question, seems the compression would be low if a valve isn’t closing fully.

Reminds me of the 50/50-90 rule: If you have a 50/50 chance at something you’ll get it wrong 90% of the time. So maybe it’s worth pulling the other valve cover?

Not sure if any issue would be super obvious by looking at the valves themselves anyway though. It could be something more finesse like valve seating etc

If you can use the glow plug holes to check compression (if it’s even relevant) that might even be easier/quicker than pulling and putting back the valve covers in my experience.
 

Pumper

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Compression test was my next thought! Motor has 157,000 miles! thanks for the reply
 

Jesus Freak

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Try feeding a mist od fuel as you crank it over.
It mat be a stuck or burnt valve, however if it ran fine when parked I'm thinking stuck which you ca see with the covers off but if you bent one already.....
Oh and


Sorry guys I Hadda do it...:p
Yikes!
 

Black dawg

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Does it sound like it is cranking normally, or does it sound uneven, with loud air noises coming out of the intake.

I would bet you are just seeing blowby vapor from the cdr valve.
 

Pumper

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Does it sound like it is cranking normally, or does it sound uneven, with loud air noises coming out of the intake.

I would bet you are just seeing blowby vapor from the cdr valve.
It sounds like it is cranking normally!
 

Clb

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Dang it Verizon ..
Try feeding a mist of fuel as you crank it over.
It mat be a stuck or burnt valve, however if it ran fine when parked I'm thinking stuck valve at worst, which you can see with the covers off but if you bent one already.....
Oh and


Sorry guys I Hadda do it...:p

I dunno if you could make out what autocorrect fubared or not.
My only issue with mist in the intake is did it possibly roll backwards when you stopped cranking?


I'd try a spriter sprayer full of fuel and fog the intake with fresh batteries in the thing.
Any damage to the valve train is done by now.
So hit it with a few pumps keep cranking for a Mississippi or 2 and fog it again.
Don't crank for more than say 20 seconds straight to save the starter ( I think that's the common concensus here)...
Don't just hose the intake and hydrolock it.

:cheers:
 

KansasIDI

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I agree. Either that or some vapor from an open intake valve where the air/fuel mix in the cylinder got hot enough to vaporize, but not hot enough to ignite.
My 6.9 did the same deal with smoke out the intake while cranking, or for a short time after shut down. CDR valve was a bit dirty, cleaned it up and it wasn’t quite as bad. A couple days later I swapped the CDR valve for a road draft tube. No more smoke out the intake.

None out the intake on my turbo 7.3, it also has a road draft tube.

And my service truck, it still has CDR. No blowby while running from oil cap, no vapor or anything. Even with the air filter off. No visible vapor flowing from the CDR. Also doesn’t do the smoke thing. Low mileage original engine though.
 

Jesus Freak

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Dang it Verizon ..
Try feeding a mist of fuel as you crank it over.
It may be a stuck or burnt valve, however if it ran fine when parked I'm thinking stuck valve at worst, which you can see with the covers off but if you bent one already.....
Oh and


Sorry guys I Hadda do it...:p
Hey, sorry for the delay on this, but it hit me today that I hadn't commented on the resurrection of this picture. So here goes:

I'm not a "horseman" by any stretch, but I do have horses and study equine a bit. In @Clb s picture you will notice that the horse's mouth is open a bit, that's because horses are stubborn like our fuel system and it's still trying to suck air just like our fuel systems. Even though the person you bought the horse from and the makers of Facet fuel pumps assure us that our beasts have great digestive systems and will poo healthily according to schedule, they're still prone to clog up, colic, and die.

Note: this will only be understood by people who really know equine.
 
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