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92 Landcruiser hard hot starting

I have a 1992 Landcruiser with ~170k miles I've owned since new. It has been almost troublefree until this summer. Now it frequently won't start when hot. It cranks fine but won't fire at all. This problem only occurs when it is hot and has been shut off for a couple of minutes up to about a half hour (hot time under the hood). It will start up right after shut down just fine.

I have pulled a plug and they are dry (no fuel on them) during these episodes. However there also is no spark if I ground a plug and crank it during an episode.

One other pertinent detail is that I recently replaced the original thermostat because the engine had begun to run hotter under load. The old OEM thermostat was significantly slower opening than the new OEM replacement during a hot water test and in fact wouldn't open fully until the the water boiled.

I've scoured the internet and eventually came up with the pick-up coil in the distributor as the most likely culprit among many possibilities. I changed it without any luck.

I'm still thinking electrical but not ruling out fuel problems. I am wondering if the 13+ years and recent extra heat has been cooking something. I would have already tried replacing the ignition control module but my local Toyota parts guy with 12 years experience says he has never sold one to the public or for the dealer shop. This of course doesn't mean it isn't bad but I thought I would seek some advise before I continue shotgunning my repair process. Any thoughts would be appreciated.

Scott

Reply to
Scott
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OK, no spark AND no fuel as well. I could understand just no fuel, as this suggests vapour lock or fuel filter problems. The engine runs hotter too. This suggests its running a bit lean. You need to investigate what controls both the injectors and spark. "ignition control module" ? If this is what generates the spark, its very likely NOT the problem as you've been advised.

Does the engine have a crank angle sensor of some sort, or a distributor? If the crank position is not being reported to the ECU, it will a) not cause the ignition control module to produce spark; and b) not fire the injectors because of a).

If the engine really is running lean, this suggests that another engine sensor or possibly an O2 sensor is malfunctioning.

When it won't start, does the check engine light come on? Are you getting a error code from the ECU? Are you getting any error codes from the ECU that are not severe enough to turn on the check engine light ?

Or it may just be a series of poor connections caused by age. Pull all the engine connectors you can see and give them squirt with WD40, then R/R the connections a few times. See if the problem goes away.

Stewart DIBBS

Reply to
Stewart DIBBS

Take it to a shop with a fuel pressure gauge. It sounds like the fuel pressure regulator is bleeding down instead of holding pressure. On a cold start, the cold start injector gives an extra shot of fuel to help start and mask the problem.

One other thing to try - on a U.S. spec Crusher, there is a wire that goes to the fuel pump in the LR quarter panel that comes loose, although it tends to not start whether hot or cold.

I think the no spark is a red herring - start by checking fuel pressure under the conditions when it is hard starting.

Reply to
Ray O

Thanks to both for imput.

This vehicle has a distributor. Also I did not think it was running hot as in potentially lean but rather I thought the cooling system was gradually failing.

The check engine light normally comes on whenever you turn the key and goes out when the engine starts. Interestingly enough during these episodes (I've just noticed) when the key is turned on all electrical connections and lights work except the check engine light which does not come on and the car does not start while cranking normally. When the car cools down the check engine light comes back on when the key is turned and the car starts.

I am now thinking electrical rather than fuel problems and in the process of examining the wiring diagrams. Perhaps a faulty connection to the ECM. Any thoughts would be appreciated.

Meanwhile I'm also cleaning up the connections.

Thanks,

Scott

Reply to
Scott

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