mileage?

My 86 with a 258 gets a nice 23+ US mph on the highway running around 65 mph.

I would expect the 4 banger to be really close to the same from what I have read here over the years.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

rjh44 wrote:

You mean that the 9mpg mine gets is WRONG?!?! Better than the 6mpg my '88 YJ had when the carb was going.

Can't wait till the snow melts and I can actually fix everything and get that MPG back over 15. Maybe I can even get it running again properly. Maybe.

You have got some serious gas issues my 04 TJ with a six gets 17mpg large tires and all. On the other hand the RAM gets 13 mpg go figure.

HarryS

I just did a 4 day bush run and gas station to gas station is 200 miles so I get an easy check every trip. It was still 10.9L/100km which is slightly better than 23 US mpg and I still have that beauty of a Weber-Carter BBD in there... LOL!

Just amazing what a $20.00 carb kit every 2 years does for them...

Mike

griff>

Ya I'm gonna do that in the spring ...after I replace the timing chain. I'm not a big fan of trying to drive it home with it backfiring all the time ;p

rjh44 ( snipped-for-privacy@adelphia.com) wrote on Monday 21 February 2005 11:07 pm:

I had an '81 CJ7 with that same setup a few years back. If I kept it at 55, I got about 24 or 25 MPG. If I pushed it up to 65, I got about 13 MPG. If I recall, city mileage was in the high teens.

The real adventure begins when you hop on the Chicago freeway system doing

55 MPH in -any- lane. The only thing saving you is that you're in a 20 year old Jeep and they're in an expensive new car.

You don't likely have timing chain issues. In order for it to jump a tooth, the gears must be destroyed. Those chains are good for the life of the engine and then some usually. One of my CJ steel sets is now on it's 3rd engine incarnation with the exact slop as a new on measured in degrees.

I would be suspecting something electrical like a cracked distributor cap or even a burnt valve for backfiring.

Have you checked the amount of play in your chain? Stock new they have about 15 deg of slop.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

griff>

Been through the following:

The entire electrical system. Then I had the local Jeep mechanic go through it all and replace almost all the under-the-hood wiring. He managed to get it running again after trying to retime it over and over but it only ran when the engine was fully warmed up and it would backfire quite a bit if not driven at the perfect RPM. Replaced about 15 wires, a couple of connectors, the distributor cap/rotor/plugs/plug wires. Did diagnostics on all the coils/sensors/etc.

The ignition system has been checked. The fuel system has been checked.

The only thing left that hasn't been opened up is the TChain cover. When my Jeep stalled during offroading, I'm thinking the dist cap was wet (unbeknownst to me at the time). When I was getting pulled home, we tried to pull-start it and it backfired something fierce. That *could* slip the timing chain a tooth from the force, could it not? Oh well, when it's warm out it's only like a 3-4 hour job to check that and it's the only thing I can think of. If it is the TChain that has to be replaced, is there any way to do it without taking the Rad out? Not sure it would survive.

I think the 85 has a steel gear and chain set like my 86 has so jumping is unlikely but possible.

One sneaky timing thing I don't see mentioned. Under the rotor is a felt pad that needs to be soaked with oil. This lubs up the timing advance plate and it's sleeve that sits on top of the distributor shaft. If this goes dry, the timing will seem to change every time you check it or it will stick with no timing advance allowed.

To test grab the rotor and see if you can turn it a bunch with a spring loaded snap back. If not, that could be the trouble. It should be really smooth and free in the movement.

To check the timing chain, you hand turn the engine with the distributor cap off until you reach TDC on the timing mark. The rotor should be pointing just before #1 or #6 if the chain is on the right tooth, way off if jumped. You then turn it back the other way while watching the rotor. The second the rotor moves, you look at the timing mark and that gives you the 'slop' in the chain. 15 to 17 degrees is normal for new to still good. Get higher and you could suspect a jumped chain.

Mike

griff>

Ya, we did the timing chain/rotor test and were about 22 deg off. We never checked the actual TDC by pulling a plug, though and we HAD moved the distributor slightly beforehand on a previous suggestion by someone so we might have messed up the alignment. However, it's timed enough to start, so we will double-check that in the spring again. Will also look into the rotor pad ...thanks for that tip!

I'll let ya know what happens ...