Hey all,

I have a 1984 300D that I'm somewhat nursing back to health; eventually I plan to use the engine elsewhere, but not until I get it reliably running in its current state.

I'll spare you the back story and just present my issue: I recently did a diesel purge to rectify a bad-fuel issue. Unfortunately, I didn't drain out enough of the bad fuel prior to reconnecting everything (it was red/farm diesel, but was likely dirty). I thought diluting it in the tank with about 5 gallons of good diesel would do the trick. Unfortunately, nope; after the successful purge, as soon as the red stuff hit the fuel lines, it stopped running again.
So I drained the tank all the way down, and tried to do a purge again; this time, it wouldn't fire. I cracked open parts of the fuel assembly, and here's what I know: 1) there is fuel being pumped through, as evidenced by the return line in my diesel-purge bottle. 2) at least number #1 and number #4 injectors are not getting any fuel (I don't know about the rest)

I've been reading up, and my inkling is that it may be an air pocket issue.

Regardless, can you answer the following questions:
1) if you do have an air pocket issue, can you just crank the starter, and eventually it will clear - without opening the injector lines?
2) Or, do you have to open up the injector lines, and cranking the engine will eventually clear them?
2) Is the source of pressure that pushes fuel out the return line the same source as what pushes fuel into the lines leading to the injectors? (i.e., is there more than one fuel pump?)


Also, anything else you might find helpful - much appreciated.

 

Hello from Canada, Forced Induction is correct if in fact air is your issue. He answered your 3 questions well. However a good question is what is the red stuff in your tank. Small amounts of power steering fluid and small amounts of automatic transmission fluid , preheated and well mixed are usually not an issue, However they suffer from 2 problems that effect diesels. #1 they are a higher viscosity and tend to immediately settle to the bottom of your fuel filter , and your fuel tank. #2 Manufacturers usually add a fire retardant to these products. That lowers your fuels cetane rating. The effect is similar to gasoline addition in large amounts. Your diesel simply stops firing. The cure that I used when experimenting with a Nissan SD 20 was a 2 tank system with preheat and a 3 way valve. If I made a mistake with my canola based bio diesel I had to switch to pump diesel and hand pump until I cleared all of it out. Then crank the engine until it started to fire. I hope your tank is not full and IF in fact someone has dumped some unknown red fluid in it you may have an issue.,. If it is you will need to jury rig a 20 l can with clean fuel and a suction hose connected to your prier pumps inlet. Pump until clean diesel comes out the overflow, Start your engine. Get it fully warmed up. then reconnect to your main tank. I really wish you the good luck that it is only air. Allan