I know this is an F150 site, but it has been a very good resource for me, so I thought I'd post a problem that my buddy is having with his Dakota. We went out mudding yesterday and he drove through quite a bit of water. He filled up to half a tank afterward and only got 40 miles out of it. I'm way too lazy to do the math, but he said it came out to like 5 MPG. He's got a 98 with a 3.9 V6 5-speed. He said that he can smell gasoline in his exhaust so for some reason it's not completely burning. My guess would be water in the ignition system somewhere, but I'm no expert. Also, this may be far fetched, but what would happen if he accidentally filled his truck up with diesel?

 

How is it running though? Is it blowing black smoke? Missing? CEL? We need more info than just "5MPG".

Diesel fuel? Well, it wouldn't even run at all, much less have poor economy.

 

I haven't actually driven it so I couldn't tell you exactly how it is running. He told me that it is running a little rough and seems a little hesitant when accelerating. His CEL has been on forever so That's not really of any help.

 

i always wondered what happens if you accidentally put diesel in a gas engine? are you really screwed after that or what??

 

When I was up in superior snowmobiling, I seen a guy fill up with diesel and he started up his sled, went about 20 feet and then it was done. Just completly shut down. Then he had the 100 guys waiting in line for gas laughing at him. lol bad news bears

 

lol lol that must have some been some real ball breaking!!!. so i guess after that you looking for a new engine huh??

 

maybe check the O2 sensors?? in my old cherokee a few summers ago went thru half a tank of gas going to work (15miles) in the morning-- you could watch the needle drop- ended up being the O2 sensors sending false signals back-

 

Yeah, that's what it sounds like to me. Maybe some water got on the 02 sensor and shorted out the wiring or something. Because it seems to me that if he's smelling gas the system isn't noticing that the fuel/air ratio is way off. I would try 02 sensor, not like they're real expensive anyway.

 

O2 sensors is exactly what I thought. He said that he got under the truck and the catalytic convertor was glowing red. I mentioned the O2 sensors to him and he was like "Oh yeah, one of them was pretty much ripped in half when we were off road. I forgot to tell you." Lol. If it's still acting up after we replace the O2 sensors I think we'll look into a new cat and if that doesn't fix it I guess I'll be back on here. Thanks.

 

what about that DPFE thinger? anyone savvy about that thing? i thought it had some control of fuel

 

Well on FORD motors the - Dif Psr Fd Eht - Almost always sets a fault code when plugged. The PCM calls on this for readings and when there bad, they jump way outside of parameters. You get a MIL.

I think excessive fuel consumption derives from lack of maintenance mostly. A fouled TB and TB elbow's EGR ports and thruways - The butterfly can get caked and not fully close - The MAF gets dirty and eventually the sparkplugs carbon up then the O2's sends back freaked out readings , but as long as it's within the parameters, your comp will adjust until it eventually can't compensate anymore. Then you'll get a MIL..

So many replace O2's when there perfectly fine. Although it is more common for 4sixes to foul up the TB , it happens in 5fours as well..

It's a maintenance thing and it needs to be gone thru.

Trade that dodge in lol - That things prolly full of problems..