Need Help Diagnosing

So to start a Full Service station put 8.7 gallons of unleaded into my 05 Passat TDI. Fuel tank was siphoned of over 12 gallons, then refilled with diesel. Car started fine drove it 304 miles straight and after stopping to get food it would not start. It would crank and crank and would not fire. Had it towed to a shop were it sat over the weekend. They got to it Monday and it fired right up. Had them replace the fuel filter as it needed one anyway. Went to pick it up Tuesday and it doesn't start, tech comes out and cranks it for a good 10 seconds and it fired up. Plugs the scanner into it and no codes, suggested it might be the plugs or the lifter pump. I went and ordered a lifter pump from ID Parts and installed it. Had no issues on short trips around town and to work. Drove it 80 miles and went into a store and came out and it cranked for a good 10 seconds before starting, but the no issues on restarting on short runs around town. Drove it back home 80 miles and let it sit in garage for a few minutes and it took about 15 seconds of cranking for it to start. So since the fuel filter and pump have been replaced, is this an injector issue or possibly something else? It runs fine with no knocking or rough idle. Ran some Diesel 911 in the tank on the first fill up after getting it from the shop and haven't refilled it yet.

Is the cel light coming on when you turn the key to the on position?

Yes it comes on along with the rest of the normal lights on the dash, goes away with them all when the engine starts.

Just thinking out loud. Have seen hard start issues with injector O-rings leaking down after sitting a while. Wonder if the gasoline might have washed them down or "cleaned" them and now not sealing off after sitting a while

vwztips said:

Just thinking out loud. Have seen hard start issues with injector O-rings leaking down after sitting a while. Wonder if the gasoline might have washed them down or "cleaned" them and now not sealing off after sitting a while

Click to expand...

Possible I guess. But it was sitting for over a day before I drove it on a 80 mile trip. Started at the house fine, but after the first stop after driving for over an hour it started hard.

Are the injector O-rings replaceable or are they one of those things where the whole injector needs to be replaced? Or can they start to reseal after running the correct fuel through them for awhile?

Is there a compression test for the o-rings? I don't want to take it to a shop and blow money on hunting down this stupid issue. I'm already down $500 after the work that's been done and the new fuel pump...

Could be the tandem pump has a air leak, or one of the hoses going to the fuel filter is allowing air bubbles somewhere. Perhaps temporarily installing a clear tube between tandem and fuel filter to rule out.

That sounds normal until the cetane reducing gasoline is purged from the system. Cold start is fine because it preglows and afterglows. Warm restart it doesn't, but with the mixed fuel in there it needs that extra help to get going again. The Diesel additive you put in just made it worse.

Recheck the connections at the filter, but it sounds like to just need to run that tank of fuel completely out.

Does your car have the "diesel fuel only" sticker inside the filler door?

Many years ago VW sent out to all B5.5 passat owners a yellow sticker that goes right next to the filler neck to help prevent the mis-fuelling issue the OP faced

If I was in the OP situation, to prevent this from happening again I would make a sticker and put it inside the flap or even on the filler door.
Or, better yet, pump your own fuel.

(I am now the owner of a gasser, Lexus LS430, first non-VW diesel car I have owned in 20 years. I'm afraid I might accidentally pump diesel in it out of habit and so made my own sticker on the door "premium gas only" just to remind myself.)

By the way, if that car in question in this thread was mine I would be sorely tempted to completely drain every drop of fuel currently in the tank out, and refill with fresh fuel. God forbid I ever misfuel my VW diesels that is what I would do .

This was the first and last time I haven't pumped my own fuel.

It has a sticker on the fuel door that says diesel in English and 3 other languages and the fuel cap says diesel on it twice in nice big bold letters.

I'm currently running the tank as low as possible before refilling it ? ugh

Tom in PT said:

Does your car have the "diesel fuel only" sticker inside the filler door?
Many years ago VW sent out to all B5.5 passat owners a yellow sticker that goes right next to the filler neck to help prevent the mis-fuelling issue the OP faced
If I was in the OP situation, to prevent this from happening again I would make a sticker and put it inside the flap or even on the filler door.
Or, better yet, pump your own fuel.
(I am now the owner of a gasser, Lexus LS430, first non-VW diesel car I have owned in 20 years. I'm afraid I might accidentally pump diesel in it out of habit and so made my own sticker on the door "premium gas only" just to remind myself.)
By the way, if that car in question in this thread was mine I would be sorely tempted to completely drain every drop of fuel currently in the tank out, and refill with fresh fuel. God forbid I ever misfuel my VW diesels that is what I would do .

Click to expand...

Every diesel conversion I've done asside from a 1967 fj40 required me to remove the little safety flap from inside the filler tube as the diesel nozzle is too big to fit into the gasser hole. Gas engine(carburetored at least) will run up to at least 15% diesel, they just smoke like a freight train. I have gas eqipment come in on a regular basis where the neighbors uncles kid borrowed the mower and filled it up with whatever fuel can was in the garage. Kerosene, diesel, 5 yr old gas etc.

I had one guy who kept bringing in a gas john deere tractor every 3 mos or so and always argued there was absolutely no way diesel was getting into his fuel and that we didnt repair it right the last time we worked on it. 3rd and last time it came in i didn't get his money for the bill but apparently he was pissed to have to pay again. The counter guy finally got him relaxed, paid and out the door when the customer read his bill. I was tired of him always arguing over his bill so the ticket read "if customer insists on putting diesel fuel in his gasoiline powered tractor I will happily work up and estimate for a diesel engine conversion as that is the only way this tractor will run off of the fuel he's putting in the machine"

Apparently he came back into the store and flipped out on my guy, again arguing it was impossible that he was getting diesel in his tank.

About a month later he called the owner of the shop apologizing, his neighbor had been borrowing the mower every few weeks to mow an empty lot between their homes and he would top off the tank to be nice. Well the neighbor filled up his own push mower and noticed it smelled of diesel and walked over to let our customer know just incase it hurt anyting.

oilhammer said:

That sounds normal until the cetane reducing gasoline is purged from the system. Cold start is fine because it preglows and afterglows. Warm restart it doesn't, but with the mixed fuel in there it needs that extra help to get going again. The Diesel additive you put in just made it worse.
Recheck the connections at the filter, but it sounds like to just need to run that tank of fuel completely out.

Click to expand...

Well I ran it to pretty much empty. Refilled with 15.969 gallons of diesel and when I went to restart it I had to crank it for 15-20 seconds to get it to fire. This was after driving it about 15 miles...

It's looking like off to the shop it goes, I guess...