Diagnose leaky injector, SPFI

[hooziewhatsit]

'91 Loyale, SPFI, 5spd, belonging to my brother-in-law.

 

For the last couple months, this car has had issues starting. Would crank over just fine, but never actually start.

 

First time I looked at it, when it wasn't starting, there was good spark at the coil, bad spark at the plugs. So, new cap & rotor and it was fixed for a week or two.

 

Since then, it's continued to be intermittent. Start some days but not other. Second time I looked at it, was able to get it to start by holding the gas pedal down while cranking (clear flood mode). It did have good spark at the plugs that time. This has worked for my BIL sometimes (clear flood mode), but not always.

 

I currently have a can of seafoam in the gas hoping to clean out the fuel injection system, but it hasn't helped yet (hasn't been driven a ton since then).

 

So, does this sound like a leaky injector? Any other way to diagnose if that's the problem or not? How hard to replace the throttle body/injector (I have a spare).

 

edit: oh yea, I think it's a leaky injector, since it (usually) won't start until cranking several times with the throttle floored. Seems to me the injector is leaking gas into the manifold and flooding it. :shrug:

 

Thanks,

-Dave

[kayakertom]

Have you timed the engine recently? Using NGK plugs? Good plug wires? Once you have it running does it have normal power and normal gas consumption? Seafoam might help a clogged injector, but your motor symptoms don't sound like a clogged injector.

[hooziewhatsit]

oh yea, forgot to mention that.

 

When it's running, it sounds and runs fine. Getting ~30 MPG. Timing is right on. I haven't done a tuneup on it yet, as I'm about to pull it to replace all the seals.

 

Thanks,

-Dave

[GeneralDisorder]

You don't have to replace the whole throttle body - the injector pops right out with a pair of channel locks - twist and pull after you remove the top four screws holding the cover in place. Easy enough to try anyway but I doubt that's your problem

 

I think your problem is either ignition related (Possibly a weak coil or intermittant distributor) or you have a bad coolant temp sensor that isn't telling the ECU the engine is cold.

 

Could be a fuel pump that's refusing to kick over when cold. It happens.

 

If the injector was a problem, then the engine wouldn't run right after it did start.

 

GD

[hooziewhatsit]

If the injector was a problem, then the engine wouldn't run right after it did start.

 

GD

 

ok, that makes sense. This next weekend when I reseal everything I'll clean everything else as well. Can't hurt at least.

 

-Dave