Fuel mixing with oil

stevesLX · Mar 23, 2007

Guys I have fuel mixing with my oil and I am still burning rich. I am clueless as to what elso to do with this thing. If I stomp on it ungodly amounts of black smoke comes out and when it isn't black smoke its blue smoke until I let up off the gas pedal. I have went as far as turning my fuel pressure down to 27Lbs and it is still running fat. I changed my oil again only 200 miles on it and its black as coal and super thin and smells like gas. I have been using 10W30. But I put 20W50 in last night. I have no codes. Cylinder balance test was fine. Compression test every cylinder holding at 150 with and without oil. I did a leak down also no compression lost anywhere. Something is definetly not right. This is a 302 with 24# injectors, 75MM TB, 73MM C&L MAF, Edelbrock 5.0 performer intake and manifold, 303F cam. This car has a high volume oil pump I have heard of these motors haveing oiling issues with these high volume pumps. I have been considering on pulling the motor and putting a standard oil pump on it. But I dont think thats causing the fuel problems and the blowby I'M getting. The motor is lucky if it has 1000 miles on it since I had the lower end rebuilt.

TheBocSez · Mar 23, 2007

I would venture to say that you have an issue with:

1 or more fuel injectors hung open or leaking causing excessive fuel to enter the cylinder.

A problem with your C&L MAF, either the wrong sample tube or something like that.

Or lastly, a leaking AFPR causing fuel to be sucked into your combustion chamber via the vacuum hose into the upper intake.

Either way, I think all of your problem is too much fuel and not an oil blow by if your running really rich and have all of the other symptoms you describe above. I think the oil issues maybe from it being thinned too much from the fuel.

Check the vacuum hose on the AFPR and see if its wet with fuel, Make sure the color mark on the C&L Sample tube is correct for your MAF, and lastly I would check the injectors. Maybe put the 19's back in witht he correct sample tube and see if it gets better.

stevesLX · Mar 23, 2007

Bare with me here because I am still learning as I go but what is the AFPR that you are talking about? And I dont have any 19LBers to throw back in. I know where I can get a used set off of a 93 T-Bird 5.0 HO not sure if those would work or not. If the vacum line you are talking about is the one that goes from the vacum tree to the back of the manifold it never has fuel in it just a little bit of oil here and there. Thats because of my PCV there wasn't a screen in the intake but I have put one in there now. Also that same vacum line doesn't have any type of clamp on it it just slides over the tube coming off the back of the manifold. Is there anyway I can tell if a injector is sticking or anything. I installed new plugs last night and gapped them at .054. The last set I had in there I gapped at .045. Not really sure which is correct but I really can tell or see a difference. But like I said earlier you can be driving down the highway in 5th gear just cruising along and downshift into 4th and stomp on it and blue smoke will shoot out until you let off of it. Now from a dead stop you can stomp on it and when you hit 2nd gear and still got your foot in it you would think it was a diesel engine its nothing but black smoke coming out until you get back out of it.

SVT32VDOHC · Mar 23, 2007

I would have to agree with the first reply. You may have a stuck injector just dumping fuel. I will also add, that I have heard of high volume oil pumps giving certain motors issues/problems. I don't know when you are supposed to use a high volume oil pump, but you might not need one for your set up.

TheBocSez · Mar 23, 2007

AFPR = Adjustable Fuel Pressure Regulator

Since you said you turned your fuel pressure down to 27lbs. I assumed you have an adjustable one. The vacuum line I was referring to is the one that goes from the top of your fuel pressure regulator to a fitting in the back of the upper intake manifold. Your fuel pressure regulator is a vacuum sensitive rubber diaphram pretty much. If it ruptures, its possible for fuel to be sucked through it into the upper intake via the vacuum hose.

Also, if I remember correctly, your injectors require a minimum fuel pressure to operate correctly and I think that 27lbs is too low.

I agree that it sounds like you have a fuel and oil issue, but Im going to stick by my original opinion and say that the fuel issue is the biggest problem of the 2 right now based on your compression test and leak down test.

I see that you posted another thread about the MAF on your C&L. which may be the problem. Wrong signal from there and it will throw your air/fuel way off. If the sample tube the right one for 24's? For an 86-93 73mm C&L with 24lb injectors, you should be running a sample tube with a blue paint mark on it.

Like I said earlier. I would address the MAF and AFPR 1st since it doenst really require you removing too much. If both of those are ok, then check the injectors.

The one thing that seems a little weird is that you have no codes. It would see that if your car was running as rich as you say, that you would have some sort of code from the O2 sensors indicating such.

Im sure someone with far greater knowledge than I will chime in soon though.

TheBocSez · Mar 23, 2007

stevesLX · Mar 23, 2007

I have codes but none related to the fuel problems. I have a smog pump code and egr codes and A/C codes, thermoactor codes. All of this stuff has been removed. The smog tube holes on the heads have been plugged. I have nothing that relates to fuel though like you were saying. I have a blue tube for the MAF. How exactly can I troubleshoot the AFPR? You know I am going to add this in also I have a ***** load of valve train noise which I think relates back to the fuel thinning out the oil. This valvetrain noise has been going on since I put the motor back together last month. I just hope the guts in the lifters 'aint all beat up. I just replaced them last week hopeing it would quiet down and no such luck. These are stock heads with non adjustable rockers. I have more than enough preload. Even after putting in 4 quarts of 20W50 and 1 quart of Lucas Oil stabiler its noisy. And its only noisy when you drive it or rev the motor. Its quiet at idle.

TheBocSez · Mar 23, 2007

You should be able to test the AFPR with a hand held vacuum pump, Put about 10lbs on it and it should hold.

Noisy valvetrain is different. When I had issues, it was always louder at idle than at speed.

stevesLX · Mar 23, 2007

From which side do I want to test the vacum on this the manifold side or the AFPR side. And yes you cant hear anything at idle but when you give it gas or drive it its ticking and chattering away.

TheBocSez · Mar 23, 2007

Connect the vacuum pump to the AFPR.

stevesLX · Mar 23, 2007

O.K. I checked the vacum hose and it is bone dry. I will check the vacum on it when I get home tonight. Lets say I get 19LB injectors will my fuel rail I have now work or do I have to change it all out?

Fuel mixing with oil

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