Still getting fuel in oil
Thread Starter
Cruising
Joined: Jun 2018
Posts: 11
Likes: 2
From: Victoria BC
Still getting fuel in oil
I posted a thread several weeks ago about this and did a bit of investigating. I have the oil pan drain plug out and when I turn on the ignition the fuel pump kicks on and fuel pressure goes to 30 psi then I hear the relay click off the pump. Pressure immediately drops to zero and a few minutes later fuel starts to drip out of the oil pan. I purchased it with this problem. I was told by the previous owner he had replaced the injections, and the fuel pressure regulator. I have tested the cold start injector, and the return fuel line is clear. Is it possible, or reasonable to pull the fuel rail up several inches, leave it connected to the fuel lines, and turn on the ignition. I am thinking I will see fuel spraying out of an injector or something leaking. I assume it's a big leak as the pressure drops immediately. The car is a 1988 corvette L98. Any help appreciated.
Race Director
Joined: Oct 2008
Posts: 17,982
Likes: 1,074
From: Lansing MI
I posted a thread several weeks ago about this and did a bit of investigating. I have the oil pan drain plug out and when I turn on the ignition the fuel pump kicks on and fuel pressure goes to 30 psi then I hear the relay click off the pump. Pressure immediately drops to zero and a few minutes later fuel starts to drip out of the oil pan. I purchased it with this problem. I was told by the previous owner he had replaced the injections, and the fuel pressure regulator. I have tested the cold start injector, and the return fuel line is clear. Is it possible, or reasonable to pull the fuel rail up several inches, leave it connected to the fuel lines, and turn on the ignition. I am thinking I will see fuel spraying out of an injector or something leaking. I assume it's a big leak as the pressure drops immediately. The car is a 1988 corvette L98. Any help appreciated.
Last edited by PatternDayTrader; Sep 10, 2018 at 07:55 AM.
Melting Slicks
Joined: May 2014
Posts: 2,897
Likes: 592
From: New Port Richey FL
There are only 2 ways that Fuel can get in, 1 injectors, 2 Fuel Pressure Regulator Vac. line. If the leak is as bad as you say if you carefully remove the Vac. line from the Regulator and cycle the key I would think it would show its self by pushing Fuel out of the Regulator proving a Bad Regulator. If not Injectors
Last edited by s carter; Sep 10, 2018 at 08:10 AM.
Le Mans Master
Joined: Aug 2017
Posts: 6,943
Likes: 1,490
From: New Jersey
There are only 2 ways that Fuel can get in, 1 injectors, 2 Fuel Pressure Regulator Vac. line. If the leak is as bad as you say if you carefully remove the Vac. line from the Regulator and cycle the key I would think it would show its self by pushing Fuel out of the Regulator proving a Bad Regulator. If not Injectors
Thread Starter
Cruising
Joined: Jun 2018
Posts: 11
Likes: 2
From: Victoria BC
There are only 2 ways that Fuel can get in, 1 injectors, 2 Fuel Pressure Regulator Vac. line. If the leak is as bad as you say if you carefully remove the Vac. line from the Regulator and cycle the key I would think it would show its self by pushing Fuel out of the Regulator proving a Bad Regulator. If not Injectors
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Melting Slicks
Joined: May 2014
Posts: 2,897
Likes: 592
From: New Port Richey FL
I did pull the vac line and there was no fuel in it. As you say, there are only two ways for the fuel to leak so it must be one or more of the injectors. I wouldn't have expected a sudden drop in pressure if it was an injector. I would have expected a more gradual decline in pressure. Oh well I guess it's off with the fuel rail !!!!!!!
Last edited by s carter; Sep 10, 2018 at 11:21 AM.
Melting Slicks
Joined: Nov 2013
Posts: 3,451
Likes: 336
From: Greater Cincinnati Area.
They're cheap enough I'd just call John and order a set..
In fact, that is exactly what I did.. The Bosch III's are an upgrade and worth doing.
Heck, it's so much trouble getting the intake off, I wouldn't even give it a second thought.
Melting Slicks
Joined: Nov 2013
Posts: 3,451
Likes: 336
From: Greater Cincinnati Area.
Thread Starter
Cruising
Joined: Jun 2018
Posts: 11
Likes: 2
From: Victoria BC
Getting closer to figuring it out. When the injectors are unplugged the fuel pressure goes to 35 psi and stays when I turn on the key. With the injectors plugged in (electrical plug) when I turn the key I can hear fuel dumping in to the engine. For some reason the injectors are all opening. Obviously it's an electrical problem. Any ideas where to start checking?
Racer
Joined: Apr 2016
Posts: 336
Likes: 93
From: San Antonio TX
Put a noid light on the injectors. That will confirm that they are being turned on by the ECM. I had an ECM failure that caused the injectors to remain on all the time. Dumped enough fuel into the crankcase that I had to change the oil.
Racer
Joined: Jul 2000
Posts: 306
Likes: 26
From: Chandler,AZ,USA AZ
Really does sound like possibly the ECM or some other electrical problem. Pulling the injector connectors proves all of them can cut off fuel flow but something appears to be not allowing one or more of them to turn off.
Racer
Joined: Jul 2000
Posts: 306
Likes: 26
From: Chandler,AZ,USA AZ
Does it have stock injectors? Might want to take a look and be sure someone hasn't replaced the injectors and put in some low impedance ones and blown the driver in ECM. Of course there are other possibilities.
Thread Starter
Cruising
Joined: Jun 2018
Posts: 11
Likes: 2
From: Victoria BC
I have completely taken apart the fuel system. Removed the plenum and tubes. Removed the fuel rail and injectors. Looked at the fuel pressure regulator which is ok. Tested the fuel return line and it's clear. Cleaned and tested the injectors. Pulled out the ECM and took it apart. Blew on it and shook it while standing on my "left foot". Put everything back together and turned on the ignition and the fuel pressure gauge stayed at 40 psi !!!!!!!! Decided to put oil in and try to start. It started after much cranking. Blew smoke and crap out the exaust for about 2 minutes. Then cleared up and I have been driving it for three days now with no problem.
Drifting
Joined: Mar 2017
Posts: 1,897
Likes: 165
From: Nashville TN
2017 C4 of Year Finalist
Sounds like something was loose and in taking it apart you inadvertently fixed it. Nice! I would still seriously consider new injectors from Jon at FIC though. They're a worthwhile upgrade and you'll notice the power increase.