Best of Deals Car Reviews Repair Shops Cars A-Z Radio Show

1995 Chevrolet Diesel 6.6L V8 fuel issues

I have a 1995 Diesel 6.6L V8 Chevy Suburban. Two years ago I put about 15-20 gallons of gasoline in it, ran it half a mile and realized what I had done due to lost power. Siphoned the gas tank, Filled with diesel and never had a problem again, about 8 months ago one of my dumbass friends got out to pump for me and put 10 gallons of gas into about 15 gallons of diesel. Had no idea at this point. Next day I filled the tank and I have a 42 gallon tank. The vehicle started to run like shit so, once again, siphoned the tank. Never replaced, fuel injectors, fuel filter, fuel pump ect. Now it runs bad every day, but I don’t believe it is gasoline problem, I’m hoping. When I add cetane booster I have no problems and runs like a charm, same thing with diesel conditioner. If I don’t add anything in the morning, it misfires, stalls out, doesn’t gain power or accelerate, acts like it isn’t getting any gas. If I can’t get it up to 50 once it will run until I get where I’m going, then turns back into shit when I start up again. I pulled the purolator fuel filter out yesterday and it’s tar black with sediment build up. I am going to replace it on Friday as well as clean the fuel injectors. Could this possibly solve my problem. I don’t believe I ruined the fuel pump. Due to when cetane Boost is added it has no troubles what so ever. Could anyone help me out on this issue?

Sounds like you are on the right track. Replace the fuel filter and cross your fingers. I’m betting though the fuel injector pump is damaged. That’s a pretty common problem reported here w/diesel engines. Easy enough to fix.

Thanks again George on the speedy response, once I get paid I’ll probably throw down 300 on parts cleaners and test tools. For the Chevy and the BMW, I’ll let you know how it goes

Hopefully your luck will turn OP! You are experiencing some frustrating problems. Of course these things always happen in the dead of winter … lol …

If the truck runs fine with fuel conditioner, you should probably change where you buy your fuel. Many places, including national brand truck stops sell treated fuel.

This is winter. I always used a 50-50 mix of #1 and #2 plus conditioner in the winter in Minnesota. Injector pumps cost me $500 20 years ago and were kind of a bear to put in but usually you would get white smoke, poor performance all around with a bad pump. When I got a bad tank of fuel, I was replacing filters constantly until I finally dropped the tank and cleaned it out. I guess I’d be cleaning the tank out or change where you are buying fuel. Makes no sense to run fine with conditioner unless the fuel is junk to begin with.

Interesting to me anyway, when I cleaned my back garage out a few years ago, I had a spare injector pump. I took it along with some scrap to the junk yard but gave them the pump separate so they could send it in. He just threw it in the dirty aluminum bin with everything else. Didn’t know what he had. Sheesh.

I believe I had a clogged fuel injector, today it was about to stall so I threw it in 3rd gear to rev it up a bit and it kicked hard, then gained all power again and I’ve had no issues. Still need to replace fuel filter. Bc I assume it will get clogge again real soon. Thanks for the replies*

I know WIX used to make diesel fuel filters for heavy trucks tht had a drain on the botton to drain water out of the filter. Bon’t know if they make them for pickups.

I think your friend is going to owe you a complete rebuild of the fuel system.

You can put gasoline in a diesel fuel system and get away with it if you realize the mistake right away and correct it. But if you leave gasoline in a diesel fuel system for an extended period of time, the gasoline will attack fuel system components.

Gasoline contains additives that a diesel fuel system was never supposed to be exposed to.

Ethanol being one of them. Ethanol is an excellent solvent. The fuel injectors/lift/injector pumps in your diesel engine rely on the diesel fuel to keep them lubricated. The ethanol can wash the injectors clean of any lubricating diesel fuel damaging them.

Ethanol also attacks the rubber in a diesel fuel system. That could explain the tar black fuel filter.

I’ve never seen a diesel fuel system work correctly after gasoline was added to the fuel tank, and left in there for an extended period of time.


Replaced the fuel filter and just kept adding a lot of cetane boost. Apparently diesel is refined more now and my 1995 was made to take diesel before ultra low sulfur diesel came out. So I should be adding lubricants to my gas anyways to keep it running smoothly. Runs perfectly fine now. No stalling, misfiring, knocking. Absolutely nothing, ran it over 120 miles today with no problems. Thanks guys

Keep your fingers crossed!