gas in the oil..

What's a good sign that you have gas in your oil? just changed the oil about a week ago. Smells a lil bit rich. Not quite sure if it's gas or just burnt oil.... Are there any tell tale signs?? wouldn't the oil be really runny and dark? I only ask cause sometimes it takes a while to start. Sometimes if you floor it it'll start right up. Always starts right away on cold starts though....

Thanks in advance guys..

just wanna make sure that it's not getting too much fuel on warm start ups. Like I said it fires up right away when cold.

You may have an injector stuck open or one that isn't closing completely. You can test it by putting a fuel pressure gauge on the fuel rail and running the engine to get full fuel pressure. Shut the engine off and quickly pinch the fuel feed and return lines. If the fuel pressure drops, you have an injector leaking into the cylinder.

Failing that, you may also have a problem with the fuel pressure regulator. It may not be allowing gas to bleed off and is instead sending it down into the cylinder. Search for "fuel pressure regulator", there was a thread yesterday where I posted from my haynes manual on how to diagnose a faulty fuel pressure regulator.

If you do have a faulty injector, you can further localise it by listening to each injector while the engine is idling. Use a long screwdriver, put the tip to each injector and "listen" through the handle. You should hear a metallic uniform "tac-tac-tac" from each injector. If you don't, you have found your problem.

You can try running a high quality injector cleaner through a tank of gas and seeing if that frees up the problem. Spend the money on a good cleaner, not one that advises you to add to each tank of gas. Alternatively some people say that giving it a few shots of wide open throttle will sometimes clear any debris out of the injectors.
If all else fails, replace the worn injector. It might be wise to replace them all since the other's probably aren't far behind.

if the injector was bad, wouldn't it be running like crap? It starts and runs fine. It's just when it's warm, it takes a lil more cranking. When it finally does fire, it idles rough for about 3 secs. Cold start/fires right up always. Sorry, hate to irreterate myself. Just confused.

you never know, I'd check the injectors just in case.
If it isn't the injectors, check the fuel presure regulator like I said.

The only way gas is getting into your oil is through your cylinders, which emans it can only be one of a couple things: stuck injector or the fuel pressure regulator is faulty and isn't bleeding of excess gas in the return line which is forcing it down into the cylinder.

or the fuel pressure regulator is faulty and isn't bleeding of excess gas in the return line which is forcing it down into the cylinder.

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What path would the fuel take from the regulator to the cylinders?:dunno:

If the diaphram ruptured,would you see fuel in the vacuum line, so it would fail the first cheap test... pulling the vacuum line checking for fuel

what other path?

,

from what I understand, if the pressure isn't bleeding off it'll have excess pressure and continue pushing gas to the injectors even when it isn't supposed to.

What's a good sign that you have gas in your oil?

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The best way to determine this is through oil analysis, just like they do for aircraft engines. Not only will it tell you if there are normal levels of gasoline in the oil, but also it will tell you if you have glycol (coolant) showing up in the oil, and at what levels...which can indicate a head gasket problem. It also tell you how much and what kinds of metals are present...indicating levels of wear in bearings or piston rings. It also tells you the condition of the oil at the time the sample was taken.

A few years ago my neighbor (also an XJ owner and also on this board) turned me on to www.theoillab.com. Costs about $15 per test. You prepay, they send you the sample kit and you collect a sample of warmed up old oil from the stream as it comes out of the pan while changing. Mail or UPS it to them. About a week later they email the analysis to you. Last year this analysis found a head gasket problem in my son's '95 XJ before we knew it was there.

Yeah, maybe it's being obsessive, but for $15 it sure gives me peace of mind to know my 4.0 is healthy.

What's a good sign that you have gas in your oil?

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Smell is one... increase in oil level is another, and thinning of viscosity. If this is excessive, an analysis is not necessary. but oil analysis is a good thing for many issues.

from what I understand, if the pressure isn't bleeding off it'll have excess pressure and continue pushing gas to the injectors even when it isn't supposed to.

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maybe "through" the injectors....... as they have a fuel supply to them continously... the fuel rail is full of fuel.

The valving should hold back flow at pressures higher than the pump can supply......
anyone have any info on pressure rating of injectors??

clunk said:

you never know, I'd check the injectors just in case.
If it isn't the injectors, check the fuel presure regulator like I said.

The only way gas is getting into your oil is through your cylinders, which emans it can only be one of a couple things: stuck injector or the fuel pressure regulator is faulty and isn't bleeding of excess gas in the return line which is forcing it down into the cylinder.

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if this is an old engine,200,xxx or more you could just have worn rings.when they wear enough gas will basically pour right down into the oil.

thall said:

maybe "through" the injectors....... as they have a fuel supply to them continously... the fuel rail is full of fuel.

The valving should hold back flow at pressures higher than the pump can supply......
anyone have any info on pressure rating of injectors??

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yeah sorry I meant through the injectors, hadn't had enough coffee this morning when I posted.

I believe that the stock cherokee injectors are rated to 19psi or something? I just remember reading that somewhere so don't quote me on it. You can swap them out with 5.0l ford injectors with a higher PSI rating or something apperantly. I don't know what kind of benefit that would have but I have read they are cheaper than the jeep ones and fit right in. Like I said I just vaguely remember reading it in somet other posts, if you do a search for "injectors" you'll find the info on the ford parts.

i think the 19 is the rating of flow of the injector in pounds per hour....

the normal fuel rail pressure is approximately 29-31 psi when running, and static (no vacuum on regulator) is approx 39 psi...

this is from manual and a recent pressure test.....

the reports of the ford injectors is the nozzle design, there are multiple ports at the injector end, affording improved atomization of the fuel


cheers!

.

If it's getting a lot of fuel in the oil you can tell by pulling the dip stick out of the jeep after you have warmed it up. Pull the dip stick and let a drop or two land on some toilet paper. of there is fuel(gas) in the oil you will see that the center of the drop is oil and dark, and the sec ring will be much clearer and spreed fast on the paper.
if its just oil the color will not change.

if your getting fuel in from bad piston rings, there wouldn't be enough fuel in the oil to do this test.

From what i have read here so fare i would guess regulator and the the vac.line is pulling in the fuel when ya first start it up.

A dripping injector would cause cause a ruff running condition when warm and would evaporated when starting cold.

Honestly i don't thing you have a problem with fuel in your oil but that is not to say that you should take the thought of it being in there lightly!!!!!

Flash.

For this amount of fuel, the vacuum line on the regulator would consistently and constantly be wet with fuel...... and have fuel flow.......

an easy test....... turn on switch with vacuum line disconnected on regulator and watch for the fuel.........

K, had a talk w/my pops today and he mentioned putting a lighter or torch under the dipstick and see if it lights up. Seeing as how oil is much harder to start on fire it should just crackle, then eventually fire up, if at all. Did it tonight and no problems...

when in doubt change it out...... oil is cheap, bearings are not.

i don't recall why u suspected it to begin with....

I DID have this to happen ..... twice...
From a no start condition......... the oil level increased on the dipstick, which should not happen, and smelled of fuel.

first time, also noted lower oil pressure from the lower viscosity.
changed oil when i got it to running condtion again......

Then later on with another no start condition, same thing... and changed it again. when i removed filter, i used a paper towel to sop up extra oil in the housing, and it was evident by the way the paper absorbed the oil there was fuel in it.

so far after repairs, (extensive)... starting each time again, and no fuel in oil.......

.

thall said:

when in doubt change it out...... oil is cheap, bearings are not.

i don't recall why u suspected it to begin with....

I DID have this to happen ..... twice...
From a no start condition......... the oil level increased on the dipstick, which should not happen, and smelled of fuel.

first time, also noted lower oil pressure from the lower viscosity.
changed oil when i got it to running condtion again......

Then later on with another no start condition, same thing... and changed it again. when i removed filter, i used a paper towel to sop up extra oil in the housing, and it was evident by the way the paper absorbed the oil there was fuel in it.

so far after repairs, (extensive)... starting each time again, and no fuel in oil.......

.

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I suspected it because of the hard starts and the oil smelling a lil rich. The oil pressure has dropped a bit but that's common after about 200 miles after a fresh oil change.. What caused your no-start problems? Was it a complete no-start or a long cranking start.

It will change the subject a bit......
but
turning over with fuel and fire, flooding actually.......

after checking all sensors over and over, replacing some (anyway), replaced ECU... so far multiple starts in a row
i have a few posts on here about it, search my user id for the posts.