ATV Florida Forum

These were on an RV we recently purchased. As we were pulling away from the check in gate at Croom it backfired and blew both of these out at the same time. It sounded like a freakin bomb. It started back firing over and over again on the way home until it stopped running. I had to turn the distributor until it would start just to get home. I put on new mufflers,plugs,wires,distributor cap and rotor today and it still misses a little. It had a little miss to it from the day I bought it. Any suggestions what it could be? Please don't say timing chain. It would be a real beotch to change.

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                            :o       :o

Maybe it's a Tuuuma... ;D ;D ;D

keith check the carb float. it maybe drip in the intake and filled the mufflers when fuel

I'm gunna have to say timing chain :)

Big Daddy's got a good point and check for carb leakage.

Possibly , if the catiletic converters have been changed- the person didnt check to see if the pipe was full of pieces from the old converters.,  just a thought??, good luck

If your distributor was tight and  timing was correct , then have a  tech check for any codes, if its fuel injected .

Like a bad carb ,  an injector can fail staying  open allowing excess  fuel into the cylinder and creating a second combustion chamber , your mufflers.
In worst case scenarios the affected cylinder(s) are damaged .

This problem is more common with  some of the later high pressure common rail systems .

I doubt the timing chain would be factor unless it has high miles.

Good luck

My  truck  did  the  same  thing.  In  was  carb  related.  When  they  go  like  that  MAN  is  it  loud !! ;D

It will be alot cheaper to check and repair the carb compared to the timing chain. I will start with that first. Thanks.

if no loss of power -definitely not the timing chain. i used to see that alot in my mechanic days and i remember it being the diverter valve pumping air into the exhaust from the air pollution pump.(remember you need oxygen for an explosion to occur. i may be wrong  but i bet you got a pollution pump running on that. it could have also been created from a cracked distributor cap(you get a spark jumping to a cylinder that has the exhaust valve open sending the expolsion through to the exhaust. i am guessing its an 80's vintage rv, am i right?

Give me a call I will tell you how to check for a loose timming chain (904)424-4127

I got no advice for this, but that's freakin awesome.

Id@

after re-reading your symptoms-additional air going into your exhaust will not cause you loss of power(unless its causing your cat.conv. to heat up and clog)you can also perform a compression check. if your timing chain has jumped you will have low compression. if its at least 120 or higher on the cylinders than its prob. not the chain.

Who Manufactured the chassis? Ford? Chevrolet? Dodge? What year model and what engine size?

yup its the chain 8)

It's a 1986 Chevy 454 without cat converters just straight exhaust with mufflers.

Timing chain would be the most obvious response to your query however, it could also be somethin amiss in the valve train regardless of the timing chain.

DO A COMPRESSION TEST! IF A CHAIN JUMPS A TOOTH IT
WOULD MAKE IT RETARDED SO IF YOU HAD TO ADVANCE THE
DISTRIBUTOR TO MAKE IT RUN ITS NOT THE CARB..

 it was a bomb , one of those towel heads set you up ;D

Another check for this one is smell the oil. If it has a heavy gasoline scent or the oil is extremely thin like water this would also confirm the theory!

After further inspection of the plug wires I can see where two of them were rubbing against the manifold and were pretty bad. I just did a compression check and every cylinder was 125 to 130 lbs. Someone said if the compression was good then it couldn't be the timing chain. Why? Couldn't it still have good compression even if it jumped time? Some one else suggested that I remove the belt for the pollution pump to rule out a vacuum problem.

your compression is ok. if the timing chain jumped it would delay the opening of the intake/ exhaust valve hence causing lower compression.(in other words while the piston is on the upstroke the intake valve is not completely closed causing loss of compression). cableguy did you have to retard the timing to where it was originally after the repairs?

since you dont have a catalytic you could remove the pollution belt and/or plug the pollution manifolds which are mounted on the exhaust manifold.(just plug the port where the air hose goes into the manifold.)

oh and by the way, i was right on the vintage.