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Q: Accidentally filled a gas engine with much am I out? ( Answered,   1 Comment )
Subject: Accidentally filled a gas engine with much am I out?
Category: Miscellaneous
Asked by: redtippey-ga
List Price: $20.00
Posted: 13 Nov 2005 15:51 PST
Expires: 13 Dec 2005 15:51 PST
Question ID: 592587
I accidentally filled my 05 grand cherokee full of diesel-there was
less than an 1/8 of a tank of regular gas.  The jeep started right up
at the pump,  ran less than a mile, engine light went on and then the
car basically died.  I want to know how much it might cost to fix this
and what kind of (if any) permantent damage will be done to the jeep?
Subject: Re: Accidentally filled a gas engine with much am I out?
Answered By: juggler-ga on 13 Nov 2005 16:54 PST

Well, the good news is that filling a gasoline engine with diesel is
not as bad as using gasoline in a diesel engine.  There is likely no
permanent damage.

The bad news is that you're probably looking at several hundred
dollars (perhaaps up to $500) to drain the fuel tank and engine and
flush the fuel lines.  If the diesel gummed up the spark plugs and
filters, they'd probably need to be replaced, but those are minor

From the Straight Dope: 

"Trying to use diesel fuel in a gasoline engine also has unpleasant
consequences, but generally not as dire in terms of damage to the fuel
system. Depending on the proportion of diesel fuel relative to gas in
the tank, a gasoline engine will either run poorly or stop altogether,
necessitating another $500 trip to the repair shop for draining and

 "What exactly do I do to fix the car if someone accidentally put
diesel instead of gas in the tank and drove a couple miles until it
... on to the diesel problem.  Remove as much diesel fuel as possible
from the gas tank and refill it with gasoline.   You may have to crank
the car to purge the diesel fuel out of the fuel lines.  After that,
it should start and run okay.  There should be no damage to the engine
from the diesel fuel."

"Diesel will not seriously harm a gasoline engine. That said, a
gasoline engine will not run on diesel, it does not have the capacity
to ignite the fuel. So while no actual damage has been caused, as has
been stated, you will have to clean out all of the diesel before it
will run again. The mechanics tell you they have to replace all of
those parts, while really it is a matter of getting as much diesel out
as you can, and letting the rest burn off with the gas. A bit of
diesel mixed with gasoline would have the effect of a bit of oil mixed
with the gas, a litte smoke."

Also see:
"diesel fuel in a gas engine"

"What to do if you fill up tank with diesel fuel by mistake"

"Should you accidentally put diesel in a petrol engine you won?t do
any harm, but you?ll soon notice the smoke! Draining the fuel system
completely and refilling with petrol is the cure."

Also see these newsgroup threads:
" you will need to drain the tank and blow out the fuel line to
the engine. If you haven't started her up at all then there will be no problem
with diesel in the carb. A few drops of diesel left in the system will flush
straight out. You haven't damaged anything. "

"If it's diesel into a petrol all you gotta do is drain it.  Not just the tank
but the engine as well.  As the fuel will need to be replaced from the carb.
There will be no damage since diesel has less combustion than petrol so will
not harm the engine.  Basically the engine just wont go as deisel needs
compression to explode the piston and pertol needs ingnition from the spark
plug to fire it."

Here's a report from someone who put diesel in her Saturn's tank.  It
cost $120 to drain it.

search strategy:
"put diesel in" "be drained"
"put diesel in" "to drain"
"Accidentally put diesel"

I hope this helps.  Good luck!

Clarification of Answer by juggler-ga on 13 Nov 2005 16:54 PST
Sorry for that typo above:
perhaaps = perhaps
Subject: Re: Accidentally filled a gas engine with much am I out?
From: veconofix-ga on 28 Sep 2006 17:20 PDT
I agree with all the above: good answers!
A few additional comments: 
I've operated a repair shop for 30+ years: see ..
and have dealt with this problem numerous times.
The good news is that the cars were never damaged by this.
Here's the problems you'll have with a Cherokee specifically:
First, you won't be able to easily drain the fuel tank. I don't think
they put drain plugs on the tank as most imports do. The best way to
get the fuel out would be to remove the fuel line, extend it with a
rubber hose or something, and run power to the fuel pump. The best
place to do this would probably be at the fuel filter. The electric
fuel pump will pump enough fuel out of the tank to allow the engine to
start. It would be a good idea to run the tank dry, fill it with
another gallon of gas or so, then use the pump to remove that
gas/diesel mix also.  Fill up with gas and you'll be fine.

As to replacing parts, or aving parts destroyed by the diesel, I don't
think that will happen.  You might wanrt to change the fuel filter,
but even that wouldn't be mandatory.

Since your car is fuel injected and the fuel runs in a "loop" (the
injectors get fuel pessure from the in tank fuel pump, and the excess
pressure is fed back to the tank) any residual diesel will be flushed
out of the lines almost immediately.  Just run the fuel pump with a
bypass without starting the engine, just like you did to drain the
fuel.  As it runs it will circulate fuel through the loop and clear
out any diesel in the fuel loop.  The engine should then start up

One downside you MIGHT experience: the "honeycomb" catalytic
converters used by Jeep and many others are quite sensitive to
clogginbg with carbon, oil deposits, etc.  Although in all probability
you haven't done any damage to the cat. conv. this is a good reason to
get as much diesel out as possible before attempting to start it.

If you take it to a shop and they want to drop the tank, etc. I'd
suggest to them using the pump to drain the tank.  Like I say, I've
used this method many times with great success.  You should be able to
find someone to do this for $100 or so. (Maybe less).

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