VincentBanuelos

Hey guys, im new here. I need some help with my camaro.

Lets start with this..
I have a 1991 Camaro RS V6 3.1L, the car was running FINE!! beautiful!! then one day i turned it on, moved it in the grass to wash it, when i went to move it back to the drive way it wouldnt start.

Symptoms: The car turns over, backfires, when it backfires - there is smoke coming from the spark plugs in the block, and the exhaust.

Replaced: I have replaced the Battery(optima), Starter, Ignition Module, Distributor w/module, Rotor, CAP, Wires, and Spark Plugs.

I have done all this with no success , it keeps back firing, i even re-set the timing back to 0 notch and set the distributor in with the striker pointing to the # 1 cylinder. Any one have any ideas before i take it somewhere and spend 400 bucks?? Please help,

Thanks,
- Vince

bruiser

Timing chain?

VincentBanuelos

Thats one thing i do not understand, if your timing chain breaks, doesnt it usually break other things?? and if anyone knows, whats the easiest way to get to the timing chain on this model? Sorry, i know most things, but im a noob when it comes to internal components on the engine.

cardoc

I agree with the chain idea.They stretch and jump a few teeth.Its behind the frt cover behind the water pump.A quick ck is to wrench the crankshaft in one direction watching the dist.rotor,then turn it opposit direction.The rotor should move almost immediatly.When bad you can feel the slop in the chain.They don't break the gears loose their plastic coating and the chain gets very sloppey.It's actually more a gear then a chain problem but the result is the same.

Raylo

Could be the timing chain, for sure. Similar thing happened to my mom's 1970 302 Mustang once upon a time. Like Cardoc says, a worn crank or cam gear can lead to the chain skipping a few teeth. Definitely hoses the timing. Of course it could also be something more mundane but you seem to have checked most of that.

BTW, your question of damage if the timing chain breaks: That can happen in "zero clearance" engines where a valve at maximum opening will contact a piston at TDC. So when the timing is sufficiently off due to a belt/chain break (or bad slip) one or more pistons could be destroyed. I believe this is common in many DOHC designs but I don't think most Detroit OHV motors have this issue. Not sure about yours as I am not familiar with the GM 3.1.

VincentBanuelos

Ok, you all have been a big help, i will try replacing the timing chain this weekend, i will let you know if that is the problem.. Let me know if anyone has anymore ideas, would be great to hear them.
Appreciate it!!!

Raylo

Timing chain replacment is a big job so I might do some of the diagnostics Cardoc recommended first. You need to pull the intake manifold and rocker arms and all the interference to get at the timing set. But if you do it make sure to change the timing gears, too. You can usually get this all as a set. You'll probably need a puller to get the gears off. Also, be careful removing and reinstalling the harmonic balancer. These can be tough to get off and tough to put back on depending on how they are designed (keyed, press fit, etc)

I'm not sure about the 3.1 but when I replaced the cam (and timing chain&gears) on my 1994 Camaro 350 v-8 the front cover gasket where it interfaces with the oil pan was a bit of an issue. I was able to able to lower the front of the oil pan enough (without removing it, which would have been a lot more trouble) to get the front cover off. Again, it may be different on the 3.1.

Also, make sure to use the proper sealant on intake manifold bolts that go through water jackets.

Good luck and be sure to post the results.

VincentBanuelos

alright, one more question, i put a fuel pressure gauge on the car, it has pressure, but when i turn the key over, it drops BIG TIME. I saw another post on here, could it be injectors? man those arent cheap.

Raylo

Timing chain replacment is a big job so I might do some of the diagnostics Cardoc recommended first. You need to pull the intake manifold and rocker arms and all the interference to get at the timing set. But if you do it make sure to change the timing gears, too. You can usually get this all as a set. You'll probably need a puller to get the gears off. Also, be careful removing and reinstalling the harmonic balancer. These can be tough to get off and tough to put back on depending on how they are designed (keyed, press fit, etc)

I'm not sure about the 3.1 but when I replaced the cam (and timing chain&gears) on my 1994 Camaro 350 v-8 the front cover gasket where it interfaces with the oil pan was a bit of an issue. I was able to able to lower the front of the oil pan enough (without removing it, which would have been a lot more trouble) to get the front cover off. Again, it may be different on the 3.1.

Also, make sure to use the proper sealant on intake manifold bolts that go through water jackets.

Good luck and be sure to post the results.

VincentBanuelos

alright, one more question, i put a fuel pressure gauge on the car, it has pressure, but when i turn the key over, it drops BIG TIME. I saw another post on here, could it be injectors? man those arent cheap.

VincentBanuelos

Thanks RAYLO, I know its a big job, i dont really want to do it, but if it will work, ill do anything. This is my little brothers car and he wants to sell it because it wont run, he wants a Silverado. I told him EVERYONE has a silverado, not everyone has a 91 Camaro RS (in mint condition). I just want to see it running and him be proud of it. He likes my Trans Am and wants to go "Crusing" with me when we go out with the F-Body crew.

Raylo

It makes sense for fuel pressure to drop when the fuel pump turns off, but I don't know how fast this should occur. I think there is usually some residual pressure but not sure how much. In any case I don't think this would be affected by the injectors unless they were totally stuck open. I've never seen anything like that personally. Fuel pressure should be controlled by the pump and fp regulator.

Very hard to diagnose this stuff accurately via a forum!

Raylo

Oh, maybe you meant that fuel presure drops a lot when you try to start the motor? That sounds abnormal. You should look up the spec for fuel pressure for you car and see how it compares.

VincentBanuelos

yeah, pressure starts at a number, then when i crank it over, the pressure drops. Ill try to find a spec sheet. The book doesnt tell me and i cant find it anywhere.

VincentBanuelos

what is the technical name for the peice on top of the block where you plug the fuel pressure gauge into and screw it on? cause mins leaking, need a new one.

bruiser

Are you talking about the fuel rail and the Schrader valve?

mack1

Hi VincentBanuelos and welcome to TFS,

I'm voting for the timing gear shelling off some plastic teeth. If my recall is working, only the gear on the camshaft had the plastic teeth and no gear puller required. It might be detected by pulling the distributor cap off and getting some to turn the engine over while watching the rotor button. If it stops or studders, it's the chain or gears.

regards,
Mack1

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Raylo

Wow, plastic timing gears..... I've heard of them but never seen one. Yes, the fuel pressure gage connection on the rail should just be a schrader valve.

I'm like you. I can't believe your brother wants to swap the 3.1 Camaro RS for a truck. Big mistake with the way fuel prices are going... unless of course he really needs it for work or something.

mack1

From cardoc's post above.

In 1986 they were metal (aluminum) gears except for the teeth which were molded on.
They shell off like corn off a cob. I know this for sure, replaced one with a full metal one.

Mack1

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"Don't drink downstream from the herd" Will Rogers

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