318 loosing power and backfireing though carb

[sperrydan]

86 Ram W100 4X4 4 Speed. 318..
Ok this is the problem I just got the truck and had to put the Vacuum lines and stuff back together. I am 90% that I have the vacuum lines right. The air Pump is not on the truck and I have the Air Pump Hoes’s taped off .

The truck starts easy and Idles fine. I will rev the motor slowly and its ok while setting in the driveway but if a rev it fast to full throttle it will slightly die out backfire through the carb and then go wide open.
And I can drive down the road at low speeds starting in 2nd (1st is Granny ) and all is will but cant floor it. 3rd truck Backfires through car and surges at haff throttle. 4th it don’t have any power and acts like it will die and I must down shift to 3rd to keep going.


Need help guys

[impuresoul2k3]

Sounds kind of lean or cam timing could be off

[Delray Dude]

Glad to hear it's running....baby steps...right?


Sounds like it could be a few problems - Timing would be the 1st thing I'd check, carb might be gummed up somewhere - my 2 bbl was plugged (and I use this term lightly - the big ports on the back that go to the PCV were solid gunk to the nature of me having to remove the carb, getting a drill and drilling through the gunk then spraying carb cleaner forever to get it cleared).

I'd check each vacuum port to make should it's got vacuum, but probably not the problem, but you never know.....

Don't rule out a bad / weak fuel pump either - or clogged filter or blockage in the tank - these are syptoms of your problem too - engine runs fine with no load but when moving the fuel supply can't keep up.

Another extreme would be low / no compression due to cracked rings - checking compression would let you know on that.

[sperrydan]

I Have all the vacuum lines on but i dont know if its 100% right locations some maybe floped. If i have to end up changing the timing chane whats the slack thats ok in the chain. I think this motor has like 300,000k on it so its probably all the above. LOL

[Speed Dragon]

+1 on a clogged fuel filter. Sounds like it could have a bad accel pump and maybe the ignition timing is off. Doesn't miss while idling, right?

[Reed_46052]

the first thing I would check is the vac. lines - the old hard plastic lines tend to break and result in a significant vac. leak. also, check the carb. accel. pump. it could be that it is not working and would cause a bog on hard acceleration. Also, while in there check the power valves within the carb. I have seen the two power valves reversed inside the carb. and thus cause the problem referred to.

If it's the timing chain - a compression check would let you know - all cylinders would be down on compression if the chain jumped.

It is also not uncommon for the egr valve to be defective - the vac. switch to the egr might be defective. if the egr is open on hard acceleration - it will cause a lean condition as described.

Reed

[bherder]

I had a prob once VERY similar to what you describe. After replacing a bunch of parts I thought was causing it, it turned out to be a couple of bad plug wires. They were near new, (which is why I didn't even think of them) but inexpensive ones...

[sperrydan]

well I got it to run now without backfireing. Runs good. The timing was about 8 DEG off. But now a hear valve chatter. It never ends.

It gose down the road and has as much power as i would think it should and idles good. Thanks for all your help guys.

Any ideas to getting the valves to stop chatering. on a 300,000+Miles 318. lol

[DiverDwnPowrRam]

replace your lifters....while you are at it...replace the cam and the timing chain

[Reed_46052]

don't forget the lifters when replacing the cam - sounds like the engine is getting tired. at 250K I purchased a long block from autozone - it now has 20K without any problems - costs was about $900 - I cannot rebuild one for that.

reed

[Delray Dude]

Any ideas to getting the valves to stop chatering. on a 300,000+Miles 318. lol



You could try 50 weight oil - might be thick in cold weather (we don't get that here) - it might take up some of the "clearance"

[86_custom]

or some lucas oil treatment it stopped the valve chatter on a dakota i had with 320,000km on the 3.9

[HemiPar]

Just a question here, but ain't there a way to adjust the lifters or rockers? That should get rid of the clatter, right?

[Delray Dude]

Just a question here, but ain't there a way to adjust the lifters or rockers? That should get rid of the clatter, right?


Not on stock LA, B or RB motors- no adjustment - you put them on and go. If it has aftermarket, then there is a chance. My 440 has the Crane Roller Rockers and has the adjustment in it, but when you get those rockers, you have to get the push rods with them.

I think the ductile iron rockers are that way too...


Only thing is to check the rocker arms and shafts for excessive wear - could replace those if that is where the noise is - heck any bone yard will have those in decent shape - (just make sure the holes in the shafts point down to the head and that the rockers are paired 1 Lh and 1 Rh)

[Delray Dude]

costs was about $900 - I cannot rebuild one for that.




Actually you can if there isn't much (or no maching needed). A full gasket kit runs about 40-50 bucks (includes head gaskets), brass freeze plug kit is another 15 (or 9 for steel), main and rod bearings and rings are another 175 to 200 - maybe less if you shop it - if you are pulling the motor and doing it yourself - less than 300 can get a nice fresh running motor.

If you have the time, pull the motor - put it on a stand, look at it, if it's rebuildable without major machining (no major scoring on the walls, etc) then you can do it for cheaper - plus you know it's "right" plus the "I did it myself" factor.

[Delray Dude]

Any ideas to getting the valves to stop chatering. on a 300,000+Miles 318. lol


Another thing I forgot to say...if it's a stuck valve - you can try pouring some trans fluid (type f) down the carb when it is running - a little steady pour while the engine is running until you get a major fog out the exhaust - smetimes that cleans things up a bit - bit messy but definitely fun!!!

We used to have a vacuum line running to the intake and into the passenger compartment - had a fuel shut off valve and had the other end in a bottle of tranny fluid - when there was that pesky tailgater or other ass, open up the valve and drive on with a smile.......a few minutes later the fun begins....

[sperrydan]

is 20w-50 to thick

[Speed Dragon]

Probably weak lifters and/or worn rocker arms. A worn rocker arm can cause backfiring through the carb also. The rockers are easy to swap out, I'd grab a set from the junkyard off a late model engine, like an 89 or 91, so you get the lowest miles possible. Just swap them out as an assembly, shafts and all. Take you about half an hour, and you can install new VC gaskets while you're at it ;) If that doesn't fix the the clicking, you'll have to pull the intake and replace the lifters.

Does it click/tap all the time, or just when you get on it?

[B-300]

I would put the Qt of transmission fluid in the engine oil and run it for an hour before your next oil change.... This will clean the lifters as well.
20W50 is ok on an old engine. Listen the timing cover for a loose timing chain also.

[sperrydan]

It clicks from idle to about 3500 or so. I got it to stop backfiring and it runs very well now. Just the chartter.
I cant really hear any chatter above 3500.

[Delray Dude]

Just a thought...do you have a mechanical oil pressure guage and if so, what is it reading? a low oil pressure might cause those noises and RPM increases oil pressure....then again very worn bearing can do that too.


You might have lots of crap in the pickup restricting the oil flow and pressure.

[mikehopkinsjr]

yall are gonnagive me bad dreams or something, lol my valves click at idl also not sure on the rpms. cuase i aint gotta tach -78w-150dodge318