Engine shut off on highway, will not restart

Thanks for your thoughts, Joe. I did mention spraying starter fluid into the throttle body, with no change, so that makes me think it's a spark timing problem. Crank position indicator malfunction seemed like a possible reason but I'm getting spark, so what I read says it's okay. It was something that happened suddenly at cruise speed -- my wife says she heard a noise, but I didn't. Camshaft timing marks line up and verified by the 150# compressions. I'm back to no other ideas.

Thanks for your thoughts, Joe. The engine fires to some degree and seems to want to start but not quite or it barely starts, runs poorly for a second or two and then quits. The spark jumps across the terminals of the coils okay, and although there is some blue in it there is some orange as well, so spark but probably not a really strong spark. I've taken off the coils and cleaned all contact points and the back of the ignition module where it contacts the block. I had to do a valve job on it before, as all the exhaust valves were badly burned (I replaced the cam chain, adjuster and sprockets at that time), and it has run great for a year or two. Then I heard some chain noise so had another look inside and the chain adjuster wasn't working properly, so I replaced that again. Been working well for the last year or two until this incident. Closer inspection yesterday netted some serious wear on the intake camshaft sprocket; some teeth were worn halfway (front to back) and some were very small and pointed so I took off the cam chain cover. Sure, enough I did check the cam chain timing correctly and it's correct at TDC, but I need to replace at least that sprocket; thus, taking off the cover (so much for cheap Chinese parts). Under normal start attempt the spark plugs get wet and if I crank it a lot with no plugs, I can smell gasoline. Plugs have been gapped and cleaned several times. 150lbs compression might not be fantastic but definitely good enough to run. Gasoline/either tell me it's not a fuel problem, so my gut feeling is somehow spark at the wrong time. The problem was immediate so something changed quickly. I'm not keen on just starting to change parts because I can't figure out what is wrong, but I'm out of ideas. Over to you! Al.

Finally got the right cam chain/sprocket kit and installed it, the old one was very worn. Still the 50# fuel pressure, 150+ pounds compression, and spark. Updates include tachometer moves when trying to start. New crankshaft position sensor installed but no difference. Not much firing with foot off gas pedal. Pedal to the floor it kind of starts and runs rough, then quits. Fuel relay out I get nothing but then when spraying starting fluid into throttle body it does fire for a second or two. Maybe flooding? Fuel in tank is now almost a year old but the non-start characteristics are the same as the day the engine died. Here's a compressed video of starting attempts with no throttle, part throttle and full throttle.

Hi Joe, I sent a reply, but it disappeared, so if there's a duplicate I apologize. I'm also thinking flooding could be the problem. Today I popped out the fuel pump relay and got my wife to try starting the car while I varied the timing of some engine starting spray down the throttle body -- I managed to keep it going for about 10 seconds. With the relay back in the initial start attempt was better than in the past but partial throttle and pedal to the floor was no better. If it is flooding, I'm guessing either the computer or a sensor. Is there any fuel pressure sensor? I don't see anything in my Haynes repair manual. Thank, Al.

Hi Joe, yes that's the PCV hose. I removed a fair amount of the intake system to access the throttle body plus make sure there was no restriction anywhere. After sitting for a day and disconnecting the MAP plug, it initially resulted in a little longer run, slightly higher RPM and a little less roughness but the engine quit after 10-15 seconds. Restarting immediately after this resulted in the same rough run for a few seconds. 12v at 2 terminals on the MAP plug. TPS has 5v feed and varies from.43v to 5v when throttle is moved from one extreme to the other. Coolant temperature sensor has 5v feed and when removed it varied in resistance when run under hot/cold water.

Hi Joe, I hadn't thought about replacing the fuel filter, as the engine seemed more flooded than starving for fuel. I hadn't replaced it since we bought the Saturn a number of years ago, but I put in a new one today. Unfortunately, no change :-(. Cheers, Al.

Hi Joe, thanks for keeping on trying for me. The fuel filter was just a generic CDN$20 (US$15) for the Saturn so I doubt it was too complicated inside. I had removed the coolant temperature sender and tested it under hot/cold water to check that the resistance moved okay, but I can't remember what those numbers were. Good point on making sure it's putting out the correct value. I have not checked the intake air temperature sensor, so I'll do that. I have no live data scan tool, but I think I can get access to one when my friend returns from vacation in 2 weeks. That seems like a very logical next step. Will keep you posted! Cheers, Al.

Hi again Joe. Finally found the IAT, it has 5v to it and resistance changes correctly to temperature changes. Al.

Hi Joe, my friend finally got back and borrowed a Snap-On high end code reader. It showed code P1599, and when I looked into that it just means the engine stalled when the key was still turned on. I checked the fuel pressure again and it's 56# when the key is turned on, and while cranking (or barely running) it varies between 50 and 55#. He said there was another code that indicated something about the air intake temperature sensor (maybe that it had been replaced). I had already taken out this sensor and the resistance checks out correctly as I make it warmer and cooler, and there is 5v at the connector. Now I'm back to no ideas again. If you have any other brainwaves, please let me know! Cheers, Al.

Hi Joe, I'm just back home after our long weekend. I had tried removing the 02 sensor in the exhaust manifold, and quite the spark show. I ended up actually removing the exhaust pipe from the manifold in order to ensure it wasn't a clogged catalytic converter, or anything else in the exhaust system. No difference. Good idea, though. I didn't get a chance to see the actual code the reader showed for the intake air temperature sensor, but my friend said the reader showed a high reading and suggested I replace the sensor anyway. As I had mentioned I took it out and checked the resistance at different temperatures and it seemed to fall within specs. Do you think I should try replacing it anyway? I read in the Haynes manual that this sensor goes from about 6.6K to 8.4k ohms at 40 degrees Fahrenheit, and down to 215 to 235 ohms at 200 degrees Fahrenheit. I removed the sensor plug and installed a 220-ohm resistor but no change trying to start the engine and I got a code P113 (sensor above maximum acceptable range) on my cheap code reader. Resistor removed and plugged back into the sensor I get no codes.

Coolant temperature sensor shows 3720 ohms at 64F, and voltage to the sensor is 4.9v, so both numbers within specs.

My friend also suggested replacing the spark plugs if they had lots of miles on them, which they do, but they were sparking, and this didn't seem to go hand in hand with the engine suddenly dying on the highway. He was an industrial arts teacher that worked at a GM dealership for a while after he retired from his teaching career and was very unhappy to see the mechanics at the dealership just looked at what was wrong with the vehicle and brought up a chart showing percentages of what could be wrong, and they just started replacing parts in order of the highest percentage of failures. He said he had to quit working there after realizing how their system worked.

I had checked the resistance of the CKP, which at 797 ohms fell within specs (700-900), but for the inexpensive cost I replaced it anyway. No change. I was wondering if it could be the wiring leading to this sensor, but the wires disappear into the main wiring harness, and I hesitated to rip it all apart to try and find out where they end up. Then I was thinking if the PCM isn't getting any reading from the CKP there would be no spark.

There, back to zero again. If you have any other thoughts my ears are open. Cheers, Al.