Sudden drop in MPG and hard to start

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rjkfsm

Junior Member
Joined
Jun 14, 2013
Posts
20
Reaction score
5
Ram Year
2007
Engine
5.7L Hemi
I have an 07 1500 with a 5.7L Hemi (no mods) with an mpg computer plugged into the OBDII connector and have a bit of a problem.

I took my 6,000lb travel trailer back to the storage yard after doing some pre-season cleaning and TLC on it and I got about 12mpg going out there. Running empty on the way back, I was averaging 20mpg on the highway. About 20 miles into the return trip, the mileage suddenly dropped to 16mpg. The engine was running fine, so I kept going. I made a stop at the store and when I came back out, the truck wouldn't start. On the 3rd attempt with about 10 seconds of cranking, it fired up and ran like nothing was wrong. The computer said I was back up to the usual 19-20mpg on the highway. I got home and later had to go back out and the truck started fine. On the return, the truck didn't want to start again, but finally did.

I have no CEL and very recently changed the oil. Any suggestions on where to start?

RK
 

Copperhead7310

Senior Member
Joined
Jul 21, 2014
Posts
161
Reaction score
33
Location
Chattanooga TN
Ram Year
2014 Big Horn CCSB
Engine
Hemi 5.7
Run it for a 30+ mile freeway trip then look under it at the Catalytic Converter. Is it glowing red ? Sounds like maybe the cat is stuck. Would also cause the rich condition on the start.

Do you smell a rotten egg type smell ? May or may not help but this would be my first idea.
 
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rjkfsm

Junior Member
Joined
Jun 14, 2013
Posts
20
Reaction score
5
Ram Year
2007
Engine
5.7L Hemi
Well, I have not had a repeat of this problem and the cat converter is fine.

I am going to chalk this up as water in the fuel.

RK
 
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