Intermittent stumble hesitation and rough idle

[AKghandi]

So i have an 89 gl spfi

 

it will randomly sputter hesitate and almost backfire, buck and lose all power like it stopped getting fuel.

 

now i thought this was due to bad/water in the gas as the car had no gas cap.

 

so i drained the tank dry, oddly it ran for a whole 30 mins and drove around the block 6 times and then to the gas station with no gas...magic

 

put $20 and some seafoam in the tank. problem still persists.

 

 

it only does it after about 45 minutes of driving. otherwise it runs great although a little gutless.

 

the car came with 4 new parts still in the box, an oil pressure sender, which it needed. cap and rotor, which it needed. and intake manifold gaskets.

 

 

i replaced the stupid bosch platinums with ngk coppers and noticed something odd, the #3 cyl the electrode was almost white while the other three were tan as normal.

 

 

My guess is the timing is off leading to the gutless and rough idle but the random hesitation has me stumped.

 

could it be the fuel pump starting to go out? or could the PO have been right and the intake gaskets need replacing? i havnet sprayed around yet.

 

 

also it was low on coolant, and there appears to be stop leak in the rad... head gasket maybe??

 

the CEL reads egr solenoid. so its not that.

Edited August 14, 2014 by AKghandi

[tundrabrat]

Plug wires could be arcing... remember on my GL Sedan, I changed injectors, blew out the the cat etc, etc, etc.  Turned out to be the plug wires.

 

Good luck

[AKghandi]

the wires are pretty new, i have thought about that but the ignition system seems in order.

 

it feels like my older dodge shadow when it hit overboost and cut fuel

Edited August 14, 2014 by AKghandi

[scoobiedubie]

The coolant consumption and the white spark plug most likely means that your cylinder head is cracked between the intake and exhaust valves on #3.  You should also check the cylinder head pressure.  Loose cylinder head bolts cause coolant to leak into the cylinder and get vaporized out the exhaust.  That causes the engine to run rough.  For starters, you should replace the cylinder head gaskets.  When reinstalling the bolts, be carefull to put the long bolts in the holes that have shoulders, and short bolts in the holes with no shoulders.  Otherwise you strip out the threads in the block.  Also make shure that there is absolutely no oil on the cylinder head bolts, washers, on the threads or in the threads inside the block.  Brake cleaner in a spray can and an air compressor, is used is clean all of this.

 

If you can find a cylinder head with no cracks, that would be useful.

[Gloyale]

The coolant consumption and the white spark plug most likely means that your cylinder head is cracked between the intake and exhaust valves on #3.  You should also check the cylinder head pressure.  Loose cylinder head bolts cause coolant to leak into the cylinder and get vaporized out the exhaust.  That causes the engine to run rough.  For starters, you should replace the cylinder head gaskets.  When reinstalling the bolts, be carefull to put the long bolts in the holes that have shoulders, and short bolts in the holes with no shoulders.  Otherwise you strip out the threads in the block.  Also make shure that there is absolutely no oil on the cylinder head bolts, washers, on the threads or in the threads inside the block.  Brake cleaner in a spray can and an air compressor, is used is clean all of this.

 

If you can find a cylinder head with no cracks, that would be useful.

 

All the cylinders have cracks between the valves......it's an EA82

 

Headgasket should be changed......that is what is leaking not the BTV cracks.

 

SHort bolts in short holes, long ones in deep ones........pretty self explainitary

 

Bolts and washers should be cleaned before reinstall..........but NEED TO BE OILED with clean oil before installation..On the threads, and on the washer surface..........this is per the subaru FSM and is a standard practice.......if you don't oil them you risk friction replaceing torque and giving you a false "click" on the torque wrench before the head is fully clamped tight.

[Mechanical_misfit]

have you tried changing your fuel filter?

[AKghandi]

the fuel filter looks pretty new.

 

 

The headgasket might be an issue but thats not my main concern right now, it wouldnt cause the stumble hesitation thats the real issue.

 

plus i dont think the headgasket is that bad, the spark plug didnt look brand new, the metal part was black, just the electrode was white.

 

i dont plan on regasketing this motor as the car will be EJ'd next summer and that would be a waste of time.

 

 

 

I plan on resetting the timing when the oil pump gasket gets here. the thing leaks like crazy 

 

I'm thinking i will rent a fuel pressure tester and drive it around till it starts hesitating and see if its a fuel pressure issue

and at the same time replace the fuel filter.

[Dee2]

Definitely sounds like a fuel problem to me, When cars do the hurt dance that's my clue.  Try the simple fixes first.

 

 I had a similar problem and it was the fuel pump going out.  The car would sometimes start, sometimes not.  Sometimes it would run fine then suddenly act like it was running out of fuel then just quit.  If I rapped on the pump with a screwdriver handle a few times I could get the car going again.

 

Picked up a cheap replacement pump from a boneyard and problem solved.

[AKghandi]

Thats kinda what I'm thinking but i wann make sure its a fuel issue and not a coil or some other ignition component getting hot and acting funny.