Petrol Peugeot won't start after filling it with diesel

Hi, my sister filled up her Peugeot Break 2004 2,2 litre petrol (125k miles) with diesel to about 1/4 tank when it was almost empty, the car ran fine for a bit before it started thumping and shortly after gave up. The car does not have a fuel filter.

After towing it home we tried:

  1. Drained the diesel out of it and put in a full tank of petrol
  2. Took off the fuel line right before it goes to the injectors and petrol gushed out of it when cranking
  3. Took the fuel injectors out to inspect them and after cleaning them they spray well, even when we connected it to the fuel line and cranking it.
  4. Tried starting it with starting fluid and then it started and seemed to run fine while we kept spraying starting fluid in the air intake which we did for a minutre or two with the engine running, but as soon as we stopped it dies shortly after.

I’m stumped as it seems to me like a fuel delivery issue but like I said the injectors spray nicely when they are taken out of the engine and cranking it.

Could it be a problem with dirty spark plugs even though it runs fine on starting fluid? I tried removing them to have a look at them but I don’t have a socket long enough to reach them.

When cranking it without the starting fluid it first seems to almost start and the headlights turn on for a second but then after it’s just the starter spinning. Any help is appreciated.

Maybe pull the plugs and clean them. You’d think firing is firing though, whether ether or gasoline.

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I dont know anything about your vehicle but does it have a fuel filter? if so did you change it?

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Did we actually go more than a week without a Diesel in a gas vehicle thread ?


We might have broken a record.


“The car does not have a fuel filter”

well then the filter on the fuel pump may need to be cleaned


it was on message #1:

if spark plugs were not replaced yet (125K miles on them?), I would do that, just to be on a safe side - it’s quite inexpensive

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well then I have no clue, stand corrected and stand aside. lol

Does this car have a fuel pressure regulator? Check the fuel pressure.

I’d start by removing all the spark plugs and let the engine sit that way for a couple of days. That will help to remove – by evaporation – any diesel fuel in the cylinders. Crank it once in a while too while the plugs are out. Meanwhile you can inspect the spark plugs. If that doesn’t get it running again, ask a shop if they can run the fuel pump to drain the tank again. That should help de-gunk the fuel filter in the tank. Given what you say, which seems a good approach, my suspicion is that you are close to having this solved.

Years ago I had a VW Rabbit that wouldn’t start. I had been working on the fuel system, it started ok before I did that, but afterward it would crank but not start. I tried everything I could think of. No go. So I had it towed to the shop. It sat overnight in the shop, and they called the next day saying it started just fine, they didn’t need to do anything. Turned out I had flooded the engine testing the fuel system, and all that was needed was time for the gasoline inside the cylinders to evaporate.

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I removed the spark plugs which were all black with residue, cleaned them up and they looked good, let the engine sit for a day, then changed the air filter which was quite clogged up, and then she finally fired up without any starting fluids! I put in some STP fuel additive that’s supposed to clean the fuel system (no idea if it does anything, but figured it wouldn’t hurt), took it for a good highway drive to clean her up and now she runs like a clock! Thanks everyone for the help and responses!

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Had to reread story. You drained diesel. Cranked motor so fuel came out fuel line. So, no more diesel in system. You are 96% there. Diesel will not mess up an air filter. Maybe you need to service car more often? So, it runs. Good.

It definitely should have been serviced better, it’s my sisters’ car and not mine but I’ve told her how to do basic maintenance on it now