1999 VN800A runs rough and backfires at high RPM.

wow a 99 an oldie but a goodie , one that old id be looking at all the vac lines , for pin holes,worn spots and cracks , a vac leak will make engne run rough at idle and as you acclerate the vac goes away so hole in hose does not matter

Possibly wrong plugs,incorrect timing. My 94 5.7 TBI ran rough and found that the spark plugs were incorrect for my engine settings.

Without checking your car physically, its not possible to give you any idea what it could be or not

incorrect air fuel mixture or a leak check for damage to the intake boot or airbox

i need to know more about how its running at low mid and high rpm to help you troubleshoot and you need to check for leaks especiely the intake boot if the intake boot is leaking that will need to be fixed before running the bike asumeing that is ok or fixed run the bike listen to it at idle standing is it surgeing with a good fast acceleration off the line with you siting on the quad ? or just realy rough ticking over with little guts off the line ?

midrange rideing how does it feel is there a bwarrr noise as u accelorate hard or does the engine roar up fast

is it reaching a good top end with good pulling power or poor pulling power

are the backfires constant or mainly whyle slowing down from high revs

if all are effected but there are no leaks then it may be float / fuel level that needs ajustment fuel level in ur float bowel effects all stages of rpm low mid and high

A rich problem gets worse as the engine heats up.



A lean problem gets better as the engine heats up.



hope this helps if u dont fix it your self first try and do them little rpm backfire tests for me itl tell me a lot

i was told that some rangers have a govner or sensor that won't allow you to go over 3,ooo rmp at a idle,it will make it run rough and backfire,it' to keep you from blowing up your motor

For this types of problem,there are few help inks to troubleshoot the problem.Click the link below to go through the troubleshooting procedure to resolve the issues :----Idles rough and quits when gas pedal is pressed less? http://technoanswers.blogspot.in/2012/01/1999-ford-f-150-idles-rough-and-quits.html-----------van idles rough? http://howtobyme.blogspot.in/2012/01/2004-ford-freestar-van-idles-rough.html
--------------runs lean and idles rough? http://technoanswers.blogspot.in/2012/02/ford-runs-lean-and-idles-rough.html
-----------Car still runs Rough after tune up? http://howtobyme.blogspot.com/2011/12/car-still-runs-rough-after-tune-up.html
------------Idle flair is noticed on car? Rough idle? car will not idle? Erratic idle speed? http://technoanswers.blogspot.in/2012/02/idle-flair-is-noticed-on-car-rough-idle.html
----------High rpm in neutral? Inconsistant high RPM in neutral? http://technoanswers.blogspot.in/2012/02/high-rpm-in-neutral-inconsistant-high.html
------------Engine Backfires? http://technoanswers.blogspot.in/2012/02/jeep-backfires.html----------- Nissan stalls and bucks on Acceleration?

http://technoanswers.blogspot.in/2012/02/nissan-pathfinder-stalls-and-bucks-on.html

-----------
Nissan Pathfinder Backfires? http://technoanswers.blogspot.in/2012/02/nissan-pathfinder-backfires.html
---------How to adjust rpm? http://schematicsdiagram.blogspot.com/2011/12/how-to-adjust-rpm-on-2009-dodge-charger.html
------------Engine cuts out at 3000 RPM? http://schematicsdiagram.blogspot.com/2011/12/engine-cuts-out-at-3000-rpm.html
----------This will help.Thanks.

I Have a 1999 ford f150 4.6 that back fires and is just running really ruff when idling alot of nack fire a sord of like a pulse going on what is my problem?

Spark plug or plug wire
After that look to your coil

I worked on one of these the other day and what fixed the same problem it sounds like is I changed out the distributor cap and rotor. the rotor can be a pain to get off. and also don't cross any plug wires take one off at a time and put it on the new one.

Vacuum leaks. Check all hoses and intake bolts. Leaking EGR or plugged PCV valve. Air filter plugged. Leaking head gasket. Worn timing chain. Camshaft lobes worn. Valves burned or leaking. Fuel idle control system or sensor. Good luck!