At my wit's end with this thing and need some suggestions on which way to go, it's been down over 2 months now and I need to get it fixed.

Problem: The engine turns over and fires, RPM starts to rise then quits firing but continues to turn over. If I keep turning it over it doesn't fire again but if I recycle the ignition it fires then quits every time.

Recent maintenance: Originally I had a coolant leak at the water bypass (but otherwise it ran fine, no issues) which forced me to remove the plenum. While I was in there I replaced the injectors (178k) with the 4 hole 'flamethrower' type and replaced the valve cover gaskets and the sensors on the water bypass. Put it all back together and it did exactly what it is doing now. Tore it down and put in a new tested set of the same 'flamethrower' injectors, this time used a light bead of red RTV at the plenum and throttle body with the gaskets to ensure I had no leaks, used a thread on this forum to make sure my vacuum/fuel lines were correct (still a bit sketchy that they are right), replaced the intake duct that comes off the throttle body as it was cracked and leaking, reset ECM again, but still have the exact same results. I removed a spark plug and cranked it and fuel shot up the fender so I'm getting fuel. I checked codes but it isn't throwing any. I sold the original set of 'flamethrower' injectors and as far as I know they worked fine, he was putting them in a couple weeks ago and was supposed to call me if he had an issue. I also did a tune up on it less than 3k ago; plugs, wires, rotor, bug. I took some pics in case someone spots something simple I missed or got wrong but at this point am beginning to think it may be a problem that just happened to surface at the same time but is unrelated to the work I mentioned above.

Any suggestions would be welcome, thank you in advance.

 

Double check the coolant sensors are plugged in right, they should be keyed to only go on the right sensors but stranger things have happened..

Check for shorts on the fuel injector lines. Key off the reading should be open lead (OL), key on you should have battery voltage. If the first test shows continuity to ground, or the second test doesn't show battery voltage, you've shorted an injector wire resulting in flooding the engine.

The amount of fuel used during cranking for start up is only a few ml/cc it should not be shooting out large quantities of fuel from the combustion chamber.

 

Appreciate the response, thank you. I'm loath to removing the plenum again (4th time) unless I just have to but will check the driver's side that I can reach, all else fails I'll bite the bullet and pull it. The fuel that came out of the plug wasn't a large amount, but I could see light spray on the fender well, not much.

The thing I keep coming back to is it only fires when I recycle the ignition, as if the ignition sequence is being interrupted as opposed to a lack of or too much fuel. I find this odd because either it is flooded or starved of fuel or it isn't in which case simply recycling the ignition should't make it fire again right away if that makes sense.

 

Pretty sure the coolant gang is accessible with the plenum on, it's located at the rear and slightly visible as I recall..

You don't need to pull anything off the engine to test the injectors, all measurements are taken at the ECU..

You maybe on the right track about an ignition fault. These use a feedback/by-pass type ignition, when the STArt signal is high the ICM controls spark independent of the ECU. I think you can check this issue by using a "hot shot", disconnect the solenoid activation wire connect a hotshot to this post and battery hold the key in start position and trigger the starter. I just don't recall if STA is routed to the ICM or it determines when to switch to the ECU based on RPM..

 

Sadly that is all Greek to me, I'll have to do some digging to figure out where and what most of that is lol.

thanks for the reply!!

 

You don't need to guess about the ignition. Put the inductive pickup of your timing light on any plug wire (#1 is a good choice), and try to start it. As the plug fires, the light will flash. If it fires a few times and the flashes quit, then you have an ignition failure (and while you're connected to #1, check the ignition timing!)

As Co_94_pu says, you should never see a spray of anything from a plug hole. By design, all the fuel should be vapor before it is sucked into the cylinder. Re-checking the injectors requires work, but hardly any work at all to pull the Cold Start Injector and check to see if it is stuck open.

"Starts and runs then quits in a few seconds" is the classic sign of a VAF-COR problem. Very easy to check; jumper FP to B+ on the diag connector. If that clears up your problem, you know where to look

Do the easy stuff first.

 

Air flow meter. Cut silicone off around it there are two little pins that have kinda a points type set up when it starts monkey with them they have to close to make connection to keep fuel pump going try that

 

That's irreversible damage to the VAF. A few simple tests (already described) will tell you definitely whether the VAF is the problem at all. Without "monkeying" with it.

 

Thanks for the reply, it will probably be the weekend before I can try what you've suggested but I'll keep you posted.

 

When I first bought my runner we were rummaging around under the hood checking vac lines etc and moved the intake tube enough to slightly disconnect the intake tube. Would crank all day, but wouldn't start. Pulled the intake apart and put it all back together and it worked fine. It's happened twice since then and it's been the same exact thing.

In my case I think it was a vacuum issue or the VAF not able to read correct values.

Goodluck!

 

Ok, jumpered FP to +B,it tried to fire then sounded like it backfired through the throttle body then wouldn't fire again even if I recycled the ignition. Pulled the jumper and it went back to firing then dying and not firing again until the ignition was recycled. I won't have a timing light until Monday and will check that then.

 

I thought it might be this as well since it is so sensitive but I've had it apart and back together 4 times and replaced a cracked intake hose to the TB with zero change in symptoms. Thanks for the reply!

 

Finally got a chance to put a timing light on #1, ignition is good, never gets interupted so I can rule that out.