2.9L problems. need help.

kolton · Mar 9, 2010

well ive been having this poblem for about a week now.it started one day without waning and is intermittent. but EXTREMELY frustrating!

my 87bii 2.9l 4x4 started backfiring through the intake. and while you are drvng, and are on the accelerator, it randomly shuts out, not giving any gas or power. it does this in random gears.. some gears run great and the others are having the problem.
and other times it is really bad. backfiring constantly and my TOP speed is anywhere beween 15 and 35 mph.
oil change and tune up about 800 miles ago
i checked my injectors=good
changed fuel filter=good
i have propper fuel pressure
i checked and cleaned my distrubuter=all good
checked plugs/wires=good
and my air filter is brand new, and clean
everything is plugged in where it is supposed to be on the motor.
i checked my timing, it was a little off, i set it at 12 like the book says, and when i put the ground back on, it went to around 30. sounded good and ran like it used to. but on the way home, thr problem started again. an it has kept doing it.. threw some stp injector cleaner in to see if that helps any.

any one have any ideas? im getting more lost as time goes on.

thanks, kolton

kimcrwbr1 · Mar 9, 2010

Go through and clean all your grounds battery to chassis chassis to engine and all the computer and ignition grounds take them apart sand all surfaces and when you disconnected the spout wire when you timed it and it ran good for a bit maybe the connector is corroded take it apart clean it then add some dielectric grease when you put it back together. Most intermittent problems are a bad wire or connector or ground

jonsranger · Mar 9, 2010

mine did the same thing when i broke a couple of rocker arms, take the valve covers off and see if anything is broke and check your valve lash.

adsm08 · Mar 9, 2010

My truck has done this 3 separate times with 3 separate causes.

#1) the battery side nut of the starter relay had backed off. Check that and make sure its tight. Its under that plastic cover by the battery and the air box.

#2) The O2 sensor fell apart. Literally, just fell apart. I was under there putting a new cat in it because a back-fire had blown the flange apart from the casing and I saw the O2, in 2 parts.

#3) The roll pin that holds the drive gear to the dizzy shaft broke and was allowing the gear to slip on its shaft. I could time it and it would run right for a while, but then it would get funny again fast.

I suspect #3, but check them in the order I put them up because that's gonna be the least intrusive method.

kolton · Mar 9, 2010

well since i dont have an exhaust i deleted O2's lol

and the wiring/grounds and all that are in good shape.
i pulled the covers and checked the valves last weekend when i did my timing. nothins broke that i can tell/see

and the dizzy shaft thing. that sounds like a good possibility. cause it would explain it very well. how do i go about checking it, and fixing the problem if it is that?

thanks for all the help guys. i really appreciate it. if there are anymore ideas, im sure glad to hear them! i just want to fix this and get back on the safe side...

thanks again, kolton

WTF · Mar 9, 2010

You said that you checked your plugs and wires...just saying- did you double check your firing order? And then I'd have good look at all of your vacuum connections. Are you getting any codes?? Good luck!! :beer:

Spitfire1975 · Mar 9, 2010

kolton said:
and the dizzy shaft thing. that sounds like a good possibility. cause it would explain it very well. how do i go about checking it, and fixing the problem if it is that?

Remove the distributor. On the oil pump shaft is a gear. It is held onto the shaft by a small round pin. If the pin is there, you are good to go. If not you need to buy a new pin and install it.

You can buy a new pin and/or gear just about anywhere. I know Napa sells them.

Spitfire1975 · Mar 9, 2010

Just remember the position of the rotor, etc.... Unless you like finding top dead center on the #1 cylinder.

kolton · Mar 9, 2010

yeah, order is correct. and im sure im throwing all kinds of codes seeing how i have no emmisions and stuff. but i have yet to get a code reader. i have every kind of tool known to man at my disposal. just not a code reader

ill go check the gear here after i get some food. im really hoping that that is the problem, and its not something worse.

i know im firing andrunning on all cylinders, and compression was good when i checked. so at least i know that the connecters didnt seperate from the rod/piston again.... lol

thanks so much guys. ill be sure to reply with outcome.
anymore suggestions are still welcome.

kolton

BlackBII · Mar 9, 2010

You deleted your O2 sensor?

How do you expect your motor to run correctly if the computer is not getting a reading from the O2 sensor???

Spitfire1975 · Mar 9, 2010

you don't need a code reader, just a test light and a couple pieces of wire. search "code reader"

kolton · Mar 9, 2010

sorry, one is still in and its good. i had completly forgotten about it. there is another O2 that had been welded into the exhaust system by the previous owner, and was pointless. the other is still good.

my mistake.

adsm08 · Mar 9, 2010

kolton said:
sorry, one is still in and its good. i had completly forgotten about it. there is another O2 that had been welded into the exhaust system by the previous owner, and was pointless. the other is still good.

my mistake.

Sounds like the PO had an air/fuel meter installed at some point.

The pin can still be in the hole even if it's broken. Put the dis stem in a vice and then grab the gear and put an hex bit in the oil pump shaft to hold it still, see if you can spin the gear on the shaft with some pliers. Be gentle though because if the pin is broken it should move without a lot of effort, but if you rip on it you can break a good pin.

DL BOGART · Apr 2, 2010

Have you checked the ground wire that pigtails off the negative cable at the battery end? this is the ground for the fuel pump/relay. It commonly gets corroded and causes problems, either cutting out intermittently or dieing completely or failing to start. I've also seen them come unplugged if the lock tab has been broken off.

2.9L problems. need help.

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