# Bad diesel fuel?



## no tree to big (May 2, 2017)

Ok so we had a truck that wouldn't run worth a crap then wouldn't restart. We pull fuel filter and what should be green is yellow we drain the tank whole tank is yellow. We have 12 trucks that run the same fuel all out of the same on site bulk tank that gets refilled pretty regularly. The fuel comes from a supplier that moves a lot of fuel, but even still we would have bad fuel in more then one truck. The fuel didn't seperate after sitting for a week. Any ideas?






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## Firemech86 (May 2, 2017)

Smell like diesel? I would go down to napa and get a sample kit and send it off to find out what is going on. 
If its just the one truck, i would start by checking the fuel cooler/heat exchanger. If that is coolant in your fuel you are going to have some expensive work ahead of you.
Depending on the make and model, the exchanger can be a stand alone unit or built into the ecm.
Pull the fuel lines off of the exchanger and then pressurize the coolant system with a pressure tester. Watch for a leak coming out of any of the fuel ports.
The coolant system could have fuel in it also, so if you do find a leak dont forget to flush it really well.

If you have any engines with diesel exhaust fluid, you might want to make sure someone didnt mix any in the tank, it will make the fuel cloudy but a layer of water should have seperated.

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## no tree to big (May 2, 2017)

The truck is an 80's mack don't think she uses any coolant. Not sure a truck that old would have a heat exchanger anyways?? Only one truck in the fleet uses def and I'm the only one who even knows where it's stored. 

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## diezelsmoke (May 2, 2017)

Ask your supplier!


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## paul99 (May 3, 2017)

I'll keep an eye I this thread as that looks exactly like Diesel I drained from my brothers van after it broke down (failed injector) last summer.

The diesel specialists that happened to recover him reckoned it was water in the fuel but I'm still sceptical as after nearly 12 months sitting in a 5 gallon drum nothing has settled out it's still pale yellow and still cloudy.


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## Firemech86 (May 6, 2017)

no tree to big said:


> The truck is an 80's mack don't think she uses any coolant. Not sure a truck that old would have a heat exchanger anyways?? Only one truck in the fleet uses def and I'm the only one who even knows where it's stored.
> 
> Sent from my SM-G900T using Tapatalk


If it was bought in a cold climate it would be an option, but not standard. I'm not up on Mack trucks from that era, but what I do remember is a coolant jacket in the head around the injector to help cool it. Not sure that they can cross contaminat, but I would still pull off the fuel return hose and supply hose and pressure check the coolant system with them off. Make sure there is no leakage there. It's quick, and good piece of mind. 

This ultra low sulphur diesel is some odd stuff, it will hold about 8% water by volume in suspension and not separate. 

Send a sample off to a lab to make sure, it's less than 30 bucks.

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## gdavis24 (Jun 18, 2017)

Old truck water leak?
Bought a used 2000 F350 that started slow and ran less than perfect. The fuel bowl filled with a cloudy liquid that smelled like old paint thinner. Pulled the tank and cleaned it out...diesel, water, bacteria, broken pickup filter, etc. The plastic tank mounts under dump bed, with a depression in the top to mount the sending unit. Holes in the dump bed let rain sit on the sending unit and leak past the homemade gasket. Reinstalled with a tin roof over the tank, welded up the bed holes, and fuel looks clean ever since.


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