engine backfiring

[Kramer-MN]

just traveled from MN to Alabama...when climbing hills, the engine on our motorhome (Workhouse chassis) would backfire and sputter, blowing black out of the exhaust.....running too rich....then on the flat areas, it would just purr along like normal.

when we got to the campground, took off the doghouse and tightened all the plug wires.........any other suggestions?

thanks in advance for your help!

[4Knights]

Had same problem this last summer, bad plug wire, replaced plugs, wires, rotor, distributor cap. Ran great after that. Made to use the silcone plug juice when installing the new wires

[DriVer]

Quote:

Originally Posted by Kramer-MN just traveled from MN to Alabama...when climbing hills, the engine on our motorhome (Workhouse chassis) would backfire and sputter, blowing black out of the exhaust.....running too rich....then on the flat areas, it would just purr along like normal.

It is likely that you have a bad spark plug wire. You need to rule that out. Likely suspect would be the number 5 or 7. (driver's side)

[Max Hubrich]

Please post what RV you have, year, make and model.

My life long experience with "backfires" usually indicate an ignition problem of some sort. Some model of RV's are especially prone to burnt spark plug wires as Driver indicated. There is a fix for adding cooling ducting to these areas that have those problems.

Good luck,

[Nick-B]

Hi Kramer,

I know this may sound strange, but if the plug wire thing checks out OK, change your fuel filter.
A plugged filter will reduce fuel pressure to the injectors and make the engine run lean, so then the computer keeps the injectors open longer to compensate and pretty soon things get too rich and you end up with black exhaust, backfiring and loss of power. When you are under load pulling a hill things get out of whack really quick.
When you hit the flat areas the engine is not under so heavy a load and doesn't require as much fuel and the system can compensate with less fuel pressure to the injectors.
Give it a try. Fuel filters should be changed regularly in a motorhome.
Good Luck!

[Kramer-MN]

Thanks Max, we have a 2005 Thor Infinity Class A with workhorse chassis. Going to have it hooked up to a computer this week to see what the codes read.