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View Full Version : fuel in oil..... how can that happen with EFI??



gold-n-rod
06-20-2005, 04:03 PM
This weekend, I noticed that the oil level was up on my 5.0 mpi. The rag I wiped the stick on absolutely reeked of gasoline.

I had been wanting to change out the current oil and go with some straight weight 40, so we pumped it out and drained it into gallon jugs. There was nearly a gallon and a half (little more than 5 quarts). I put 4 new quarts back in and the stick showed exactly at the OK mark.

My plan is to run it some and see if the problem reoccurs. BTW, last weekend, after shutting it down and floating a while, upon restarting, it stunk like unburned gas and while flooring it to get up on plane, it nearly stalled and missed like hell. Remember, this is an MPI motor. Something was not right.

I put in 2 bottles of Techron and it seems to be running better since then, just a little miss when getting to plane and nothing at all like last weekend. I also replaced the fuel filter/separator.

I am guessing that I have an injector that's not fully closing (is that even possible?) and allowing gas to soak the cylinder, eventually ending up in the crankcase. Still, that seems like a lot of gas in the oil.

It is running fine, oil pressure between 20 (hot, under load idle) and 60++ at cold start, no bad noises and other than the problem last weekend, it runs very smooth at all rpms.

Hey Brad Verd, remember when you looked this boat over and you said it looked like the oil was overfilled? Hmmmmm.

Any thoughts??

Chili 18
06-20-2005, 04:26 PM
Careful with all those fuel fumes.....KaBOOM... :eek!:

MOP
06-20-2005, 05:06 PM
Please do your self a favor run it for a rew minutes then pull the plugs look for wet ones, you may have a bad injector or two which if run may wipe out the cylinder walls.

Phil

Cuda
06-20-2005, 06:00 PM
Yes, not only could it wipe out your cylinders, you could be making a bomb.

Cuda
06-20-2005, 06:01 PM
If it continues to "make oil", sell it to Exxon. :)

jstokes8407
06-20-2005, 07:28 PM
A stuck fuel injector will do it. If you can get a fuel pressure gauge on the engine. cycle the key to pressurize the rail or see if the needle drops. then unplug the injectors 1 at a time till you find the 1 that is leaking. good luck

joseph m. hahnl
06-20-2005, 08:25 PM
Does it have a carter diaphram fuel pump with a return hose of any sort?
or electronic fuel pump?

MOP
06-20-2005, 09:57 PM
It is a fuelie they run electric pumps.

Trueser
06-20-2005, 11:31 PM
.How’s the temp doing? Sometimes the motor doesn’t get warm and the computer keeps adding in fuel. This happened to my buddies SeaRay last fall, ended up being a stuck thermostat.

His oil was way overfull. We watch the temp all the time know.

Good luck.

gold-n-rod
06-21-2005, 05:48 AM
.How’s the temp doing? Sometimes the motor doesn’t get warm and the computer keeps adding in fuel. This happened to my buddies SeaRay last fall, ended up being a stuck thermostat.

His oil was way overfull. We watch the temp all the time know.

Good luck.

Good point, the needle doesn't move off the bottom setting. I think I saw it move after running/shutdown/restart but only to about 130* and then it went back down once back underway when the water began circulating.

gold-n-rod
06-29-2005, 03:53 PM
Update: Just picked the boat up from the repair shop. "Malfunctioning thermostat."

$83.11 was the bill, of course I told them what the problem was, so there was no need for diagnosis.

I will change the oil again tomorrow to be rid of the last of the gasoline contamination and then report back.

BUIZILLA
06-29-2005, 05:25 PM
When you change the oil change the filter this time and add 5 quarts.... you said you only added 4 last time which means you didn't change the filter so you still had diluted fuel in the filter, which is why you still smell it.

Jim