Rough start after sitting a few hours or overnight

[M0untaineer]

Howdy all 96 FZJ80 w/ 188K- been having an issue with rough starts in the morning or after sitting a few hours...sounds horrible and engine kicks/shutters when it tries to turn over...after I turn the key to off and hit it again, normally starts up easily and after starting runs just fine, but the rough starts seem to be getting progressively worse and more frequent....I thought maybe it was a fuel vapor lock issue and had pressure on the gas cap when it was removed, so I replaced my charcoal canister with the Duralast VC120 model...that seems to have fixed the pressure issue at the gas cap, but the rough starting problem is still there and perhaps getting worse...

Does this still sound like a vapor lock issue- maybe bad injectors?

 

[greentruck]

If it's sitting and cold in the morning, very unlikely to be vapor lock. I suppose it could be an injector, but I know next to squat about gas engine injectors, all my experience is old school diesel and yeah, they sometimes keep leaking and might cause similar symptoms. Kind of doubt if similar applies here, though.

No problems starting the rest of the day?

How about any Check Engine Light?

 

[M0untaineer]

It's thrown a 402 a few times, but I've had that happen a few times well before this issue and the CEL doesn't come on in conjunction with the rough starts...thanks for the help

 

[Tools R Us]

So, is it a turning over/starter problem or a motor running/missing problem? We have seen a few where the starter will engage and disengage rapidly, making a nasty sound, it's intermittent, sometimes does, others doesn't. Likely the solenoid going bad, all repaired by replacing the starter with a Denso reman.

 

[M0untaineer]

Thanks for the response- I don't think it's a starter problem and here's why...when I first try it it makes the horrible noise and like I said, the engine shudders/kicks...when it catches on the next turn of the key, the engine spits/sputters for maybe a second and just generally seems like it's hating life until it fully catches and then it runs fine. It only does it intermittently and seems to be more apt to do it when it's sat for a few hours and gotten cool/cold. To me it seems like some kind of fuel delivery issue or pressure related problem. Once it's started, no issues at all...runs/drives just fine. No loss of power, coolant/engine temps are just fine, pressure buildup at the gas cap is now no more.

I don't see how the starter could cause the engine to run poorly once it did engage after the second or two hesistation/shudder? I would think the starter would be the horrible noise and a start or no-start subsequently?

Thanks much...not a mechanic, and trying to figure this out on the cheap if possible.

 

[M0untaineer]

dare I say it...I'm afraid it might be a head gasket starting to go...from what I'm reading, sounds eerily reminiscent of coolant pooling in cylinder head, burning off and then starting up ok afterwards...I've noticed a small amount of coolant that seems to have disappeared (thought maybe I was working out some air that I had in when I did coolant flush awhile back)....I sure hope not...anyone got any fool proof methods for testing this theory?

 

[Oscar Witte]

dare I say it...I'm afraid it might be a head gasket starting to go...from what I'm reading, sounds eerily reminiscent of coolant pooling in cylinder head, burning off and then starting up ok afterwards...I've noticed a small amount of coolant that seems to have disappeared (thought maybe I was working out some air that I had in when I did coolant flush awhile back)....I sure hope not...anyone got any fool proof methods for testing this theory?

This would be my guess. Its still okay to run. When you drive the coolant leaks in the cylinders, then when it sits the residual pressure allows some coolant to leak in as well. After you turn it over a few times all of the coolant has burned off. Just continually monitor the coolant levels to see if it has gone down, also you could do a Blackstone oil test.

 

[M0untaineer]

Thanks...So thinking bad fuel pump, injector or head gasket issue...

Would a bad fuel pump exhibit the other classic symptoms? Seems like the check valve could be bad as well and cause similar problems

 

[Oscar Witte]

Thanks...So thinking bad fuel pump, injector or head gasket issue...

Would a bad fuel pump exhibit the other classic symptoms? Seems like the check valve could be bad as well and cause similar problems

I think the key here is that it only happens upon startup after long periods of time. A bad injector would cause problems at random I believe. I don't know about the other two.

 

[Rifleman]

M0untaineer, i would go with one of two ideas, fuel is leaking in to one of the Cylinders or water is getting in. So leaking injector or injectors, or bad head gasket, or worse, a crack in the block or head. Do you notice any white of black smoke once she starts up, and then goes away after running a few seconds? White would be water and black would be fuel. Next time after you've let it set for awhile, i know this would be some work, but pull all the plugs and turn it over. Now if you see fluid spray out of one of the plug holes you have found your problem, then you need to determine if it's fuel or water. Or if you want to just check the cooling system you can get one of those kits that has the fluid that changes color if you have an exhaust leak in the cooling system. Most of the time, but not always with a bad head gasket you'll have overheating problems too if it's leaking.

 

[M0untaineer]

Thanks- No overheating or smoke

 

[Qball]

Sounds like a leaky injector, if it sits it would leak some gas into the cylinder and cause rough start till it burns off.......my theory anyways. Some BMWs had the same issue.

 

[M0untaineer]

Sounds like a leaky injector, if it seats it would leak some gas into the cylinder and cause rough start till it burns off.......my theory anyways. Some BMWs had the same issue.

Thanks Qball- I'm gonna pull the spark plugs today and then crank it to see if gas or coolant spits out

 

[Qball]

Thanks Qball- I'm gonna pull the spark plugs today and then crank it to see if gas or coolant spits out

May not need to crank it, just peak in so see if there is any gas or coolant, also check to see if the plugs are wet. It doesn't take much to make it run rough, try cotton qtips on a stick, it should be bone dry.

If you see coolant shoot out then you better use Bar's HG fix asap till you can get it fixed or you might get hydro lock.

 

[Oscar Witte]

I would inspect the plugs as well to see if one is gunky or rusty

 

[M0untaineer]

Here's the plugs first picture is 1-2, second picture 3-4, third picture 5-6...

 

[Qball]

Are these pictures taken after the car has been sitting for a while? They look bone dry, although some of your plugs have rust on then.

 

[M0untaineer]

Sitting overnight....

 

[Qball]

Sitting overnight....

Is there any moisture at all inside the cylinder? Is not then you can comfortably rule out leaky injector or HG.

Btw how old are the plugs? I'd just change them and use a bit of high temp anti seize on the thread.

 

[M0untaineer]

Thanks Qball...No moisture...plugs were also bone dry...Plugs are about year and a half old. I think I'm gonna go ahead an change out the fuel pump and fuel filter and then go from there...