Fuel in the oil

[jamieeasley]

I've got a problem that I'm trying to figure out what the exact cause is, without just replacing a bunch of parts. The truck is a 1999 Tahoe 2 door with a little over 200,000 miles. I'm having a fuel leak down into the crankcase. The fuel pressure when running is good but when you shut the truck off it completely bleeds off in about 2 seconds. When you check the oil on the dipstick you can see that there is a lot of fuel in the crank case. I'm trying to figure out where exactly the fuel is leaking out of and how it's getting into the crank case. I've thought about the injectors in the throttle body but I'm not exactly sure how to test them. Any ideas you guys have on being able to narrow down my problem would be greatly appreciated. Thanks guys.

 

[noJeepshere]

I can't really help with your problem as I'm not too familiar with the fuel system and have no idea how the fuel would leak into the oil system, or where.

But do not drive it until you figure this out!! Fuel in the oil thins it out and will remove oil from internal engine surfaces. Basically it's a degreaser. Keep driving it with gas in the oil and you won't have a motor left to fix.

 

[jamieeasley]

Yeah I'm not driving it and I haven't been for a couple months while I got a starting issue figured out. Now that is resolved and this problem arose. I guess I'll just take off the air cleaner and all the intake piping and see what I can tell from that point.

 

[ScottyBoy]

Spider injector assembly is bad. Do NOT drive it until you get it repaired. That happened to my moms 95 Astro van and the engine ended up detonating. The gas in the fuel ignited and BOOM!
It literally blew a hole in the engine block the size of a baseball. Needless to say, it was not rebuildable, had to buy a crate engine.

 

[jamieeasley]

Is there a way to confirm for sure that it is the spider assembly? If I take off the intake manifold will I could I cycle the key and let pressure build to see where the leak is coming from?

 

[gpracer1]

It is the spider assembly for sure.
Since it is all one unit, it doesn't matter if it's the reg or injector. The fuel is filling the cylinder(s) and leaking past the rings.

 

[fire730]

It's probably just the regulator leaking. It is replaceable without changing the entire spider assembly.

Take off the throttle body so you can see in there better and you will probably notice how clean the lower intake manifold is underneath the regulator from the fuel leaking out of the vacuum side of the regulator and if I remember correctly the fuel runs over to the other side of the motor.

You will still have to pull the entire upper plastic manifold off to change the regulator but it's really an easy job.

The only other thing is if there is that much fuel in the oil you may washed out the rings already.

 

[BattelWagun]

I would replace the whole spider assembly and do a full oil change. A bad regulator (or anything on the spider, for that matter) is just a sign of things to come.

 

[SunlitComet]

Is there a way to confirm for sure that it is the spider assembly? If I take off the intake manifold will I could I cycle the key and let pressure build to see where the leak is coming from?

yes. you could but it is to cumbersome to do sometimes. And trust this coming from me, the spider assembly FP reg is the way it is getting in there. Delphi has since redesigned the injection system to resolve other fuel problems so do your self a favor and installed the upgraded unit. http://www.amazon.com/Delphi-FJ10566-Fuel-Injector/dp/B000TYLIFS

 

[tlamot01]

SunlitComet is absolutely correct on this matter. If you're going to spend the time and effort to get the top manifold off, you might as well just replace the entire spider assembly. Also, don't bother trying to find a better price for the unit - Amazon is by far the best deal.
I replaced my spider about two months ago and it's like driving a brand new truck again. Smooth idle and acceleration. I have not tested overall fuel economy gains (mainly drive in the city) but I think I'm getting about 1 mpg better in the city. For a truck that normally gets about 9 mpg in traffic, that is a big deal.

A hint on installing: Don't clamp the spider assembly in the cage until you get all your injector lines ran. The lines are really stiff and may break if you force their movement. Since they are covered in shrink wrap, you won't be ale to tell if you've damaged one. Just be careful and take your time.