My '91 B250 conversion van with the 318 engine and 4speed auto trans is killing me with gas consumption. When I bought it a year ago, I changed cap, rotor, wires, plugs, oxygen sensor and fuel filter. I get a code 55 so am wondering where to go next! I've bought a new ignition switch to install as I'm also having problems with fuel and temp guages and recall a thread that pointed me in that direction. My assumption being that it might contribute to less than optimum ignition output. The code 55 would indicate all the tbn sensors are operating correctly, or are there exceptions? Should I go ahead with the switch replacement? Any and all suggestions will be greatly appreciated. Thanks

 

Well if you told us what you're getting for MPG, then we might've been able to let you know if you're getting fair MPG or not.

A code 55 means nothing other than the PCM is done displaying codes.

 

Thanks for responding. I thought the code 55 meant no components were malfunctioning. Most of my driving is highway so I thought it had to get better mileage than that. I've considered removing the two back captains chairs to lighten the load and make it easier to haul my constructon tools and, occasionally materials. Most of the time it's empty though.

 

Code 55 means end of codes, so if you only get a code 55 that means nothing else tripped a code. Usually one gets a code 12 too, meaning the battery has been disconnected within the last 50 key strokes.

The ignition switch has nothing to do with spark strength. If the Van starts, it is fine.

A slow or slightly off O2 sensor might not set a code. Do not use Bosch. Use Delphi or NTK.
A vaccuum leak might not set a code.
The 2 wire coolant temp sensor might not set a code.

I once was getting 11 mpg highway on a x country journey driving 65. This was before I knew how to retrieve codes, but I bought a new O2 sensor and fixed a vaccuum leak and it instantly went back to 16+ mpg hwy at 65mph.

My old coolant temp sensor also did not set a code but was just within the ohm parameters. Replacement made the exhaust smell less rich.

 

Better mileage than what? You still haven't posted what you're getting.

 

In post #3 he put '8 to 10 mpg' in the subject line. I almost missed it too.

 

Totally missed that.

Is this a high-top conversion? Still sounds pretty low, though. My '90 B250 with 360 and A518 averaged about 13 mpg, 11 mpg towing. Not a conversion and we had removed the third row seat for more cargo space, but still.

 

Sorry for not responding sooner but after driving 75 miles to Kansas City, working 8 to 10 hours restoring old houses and 75 miles back home, I'm too tired to even get on the pc. Thank you again. though. Yes my van has the raised roof. I'm sure the o2 sensor was a Bosch so going find one of the other brands today. I'm also going to pick up a hi- flow cat and muffler. I had already bought a new temp sensor as my guage just lays there. That was part of my question about whether the ign. switch has anything to do with guage operation. I'm also going to do a thorough check for vacuum leaks. At present, there are non audible but am going to replace most of them. Have already done some of them, but will finish the job. Thanks Landyacht and everyone. I'll keep you posted.

 

The 2 wire CTS is for the computer only. There is a one wire CTS for the gauge.

If the T stat is stuck open, the engine might run too cool depending on ambient temps and the health of your cooling system.
It will definitely take too long to get up to temperature.
That will also hurt fuel economy.

I've been using Bosch o2 sensors and have passed my smog tests for the last 6 years and get as good a mileage as can be expected

BUt I will not be using them again. and I will replace it most likely in the next two months.

 

Check out this forum thread on MPG Improvements. Much can be applied to your Ram Van era too.

https://dodgeforum.com/forum/dodge-r...rovements.html