The injectors will not fire unless the engine is cranking, so that will explain your lack of fuel spray with the engine not running. As for why it won’t run below 1,500 rpm, I wonder if your EGR valve is stuck open. or constantly getting vacuum. Try disconnecting the vacuum line at the valve and see if it will run then. If it does, check for vacuum at the line you just disconnected. There should be none. If there is, the EGR solenoid is either bad or getting a bad signal from the ECM. If the engine still will not start, pull the EGR valve off and see it’s loaded with carbon.
mark if the EGR valve was that badly mucked up shouldn’t he be getting a code? It’s a 32 on my truck (94) and I imagine it’s the same for the 93.
@london
As far as I know my friend hasn’t been able to get access to a code reader. In California, the Autozone stores can’t lend out readers due to emissions testing regs. It may be that there are codes there, so if we can’t borrow the reader, or otherwise solve the problem, he may just have to give in and tow it to a shop.
@mark
Thanks very much for the detailed instructions. We’ll do what we can to investigate the EGR and vacuum as you described. The small fire really seems to have complicated this, unfortunately, so not sure we’ll be able to get it to run at all for the vacuum test you described. Regardless, the help is much appreciated.
–Roadtripper
As a 1993 this truck has the OBD I system. You can get the codes out of it without a code reader. Here’s one source that will tell you how: (see below - I pasted the wrong link!)
@cigroller
Thanks, this will help. I presume the process is similar for a Chevy? I have the test light, and I see on the link you sent how to find GM codes, but not sure how to recognize the “diagnostic connector”.
Doh! My bad. Here’s the GM page: http://www.extreme-check-engine-light-codes.com/GM%20OBD1%20Decoder.htm
No worries!
Now, since my friend drained the battery trying to start it, I’m assuming any codes would be gone until it runs a while…which is the first problem…sort of chicken and egg I guess. Would running while parked do it? For how long?
He had gotten it to run at elevated RPM, but since it died below that, driving it is probably not possible, and not safe, in a small town. And of course that was before the d*** little fire. No clue about how the fire and melted insulation results in no start now - even with starter fluid. I hate when that happens.
The injector fuse is probably blown from the fire or it could have burnt up the ECM. With it running on anything but part throttle and above only, it could be as Mark has stated with the EGR or it could be something else causing a massive vac leak. Like a leaking brake booster. Or it could have a bad TPS. I have also seen the port on the throttle body for the MAP sensor get restricted so there’s no vacuum. Causes it to run extremely rich, but chances are if this were the problem it would still start just not idle.
try checking the ignition module since it controls both the fuel and the spark
@ pete peters: your were dead on…the fuse had blown because the fire melted enough insulation to short out the circuit. Looks like that’s all that was damaged by the fire, it’s back to running nicely when the RPM stays elevated, around 1500 seems the minimum. I want to check the vacuum issues, as has been suggested, and how that affects the EGR. Any advice on how to check the brake booster for a massive vacuum leak? Would it be sufficient to simply disconnect and plug the vac line going to the booster, effectively eliminating the booster temporarily, to see if that changes the engine behavior? FWIW, my friend had already installed a new EGR valve, but we don’t know anything about the solenoid yet. Hopefully look at some of that on Sunday.
@ doody…can you give any guidance on how to check the ignition module? Or is that not relevant now that it does run?
All this help is greatly appreciated, thanks all!
the igntion module can be removed from the distributor and most parts stores can check it for you. its probably not relevant now. if the fire affected the tbi you might check and see if the gasket on the tbi is ok