Another vortec intake problem

[BluCallrBallr]

I'm having some difficulty finding the source of problem. My engine oil is being contaminated with gasoline. I use synthetic mobile 1 w/qt of Lucas oil stabilizer and when I service my truck, which is a 97 Z71 rcsb w/5p man my oil viscosity is diminished after 2 or 3 days and it smells of gas. So I assumed my fuel pressure reg was bad creating wash down affect. Upon pulling upper intake off I noticed oil like fluid in lower intake inside the ports closest to the firewall. Changing fuel pressure reg didn't make any difference. I'm guessing that oil blow by is occurring but how does it get mixed back in with engine oil? And what should my next step be to fix it? Oh I forgot to add my truck runs like crap and always has since 2000 despite changing to updated spider, O2 sensors, GM performance heads. Never had dummy light turn and I bought it new 16 yrs ago. I've been following this site for years but this is my 1st post I appreciate any & all educated help.


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[Big D]

sounds like your piston rings are gone. have you done a compression test?

 

[Big98z71]

I would look towards valve guides and seals. I was having close to the same problem with my diesel haying tractor last year, new head 5 years ago. Diesel in the oil, valve guides looked as if they had 20,000 hrs on them. Compression check first then look into valves and guides

 

[98_k1500]

If you put the updated spider on it, and it still runs bad, it may need a map sensor or something of the sort. It can be "BAD" and not set the check engine light if the values it is sending to the computer are valid values, but are incorrect. I would be inclined to find someone with a scan tool (not just a code reader) and look at the values of all the sensors and make sure they make sense. Sounds like your computer is telling the injectors to dump ALOT of fuel, and the computer thinks it is the right thing to do at the time, so it does not set the check engine light. Another thing to check is fuel pressure. If the return line is clogged, it will run WAY more pressure than it should, and be spraying WAY more fuel than it thinks its spraying. These are about your only two options for getting gas into the oil if the injector spider is not leaking.

 

[BluCallrBallr]

Thanks to everyone who responded to my post, I guess I will start with the leakdown or compression test 1st. I got a friend who is a Toyota wrench and he put his $3000 Snap-on scanner to it and didn't find much except not every injector was getting 100% flow (from my experience that's the unicorn if you maintain 100% w/this type of injection). When I replaced the fuel reg I noticed that the fuel meter body seemed rather worn or just plain cheap. The little wheel that you plug the reg into kinda just laid there and seem to have a lot of movement or play to it. I'm not sure how a good one fits but mine can't be right.


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[BluCallrBallr]

98 k1500 would I be able to accurately diagnose if a sensor is bad with my ohm meter using the values from a Chilton book? Where is the fuel return line ? Inside upper intake?

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[BluCallrBallr]

If you put the updated spider on it, and it still runs bad, it may need a map sensor or something of the sort. It can be "BAD" and not set the check engine light if the values it is sending to the computer are valid values, but are incorrect. I would be inclined to find someone with a scan tool (not just a code reader) and look at the values of all the sensors and make sure they make sense. Sounds like your computer is telling the injectors to dump ALOT of fuel, and the computer thinks it is the right thing to do at the time, so it does not set the check engine light. Another thing to check is fuel pressure. If the return line is clogged, it will run WAY more pressure than it should, and be spraying WAY more fuel than it thinks its spraying. These are about your only two options for getting gas into the oil if the injector spider is not leaking.

Just wanted to say I appreciate your input and I had a couple ?'s for you. Can I accurately diagnose a bad sensor using my volt/ohm meter going off of the values in my Chilton book? Where is the fuel return line? Under upper intake w/spider?

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