Trouble restarting when engine is hot

[giro]

The other thread (http://www.toyota-4runner.org/classic-t4rs/154211-difficult-starting-sometimes.html) of occasional trouble starting reminded me of a problem we had a few times last summer.

My '92 V6 manual starts up fine most of the time, but sometimes when the engine is hot and it hasn't been stopped very long it has trouble restarting. My wife hit the issue a few times, but possibly the only time I saw it was after a 90 minute drive down the mountain to Sacramento, probably pushing 80mph, around noon with it close to 100 outside. We were in a rush, picking up a gift for a wedding. BBB was just off the freeway, and I probably even came through the parking lot a little quick and turned it off quickly without any idle.

Coming back out 15 minutes later, it turned over but didn't start. I tried a few times with no luck (it would stumble for maybe 5 seconds, and then die), and then was able to push the gas a little while trying to start to get it going.

Any ideas? Basically none of the emissions stuff under the hood has been cleaned or replaced (just the air filter, plugs, and long ago the cap/rotor). It could be something there, but one thing that got me thinking was a problem over with 3000gt's where on hot restarts like this the fuel would vaporize in the fuel rails and prevent enough fuel getting to the injectors. They had a two stage fuel pump with the higher pressure not being pushed by the pump until above a certain engine RPM, so one of the most common workarounds was to bypass one of the relays, making the fuel pump always aim for the higher pressure.

Does the 3.0 have any common issues with hot restarts like that? Or if not, any ideas what to look for?

Thanks!

 

[giro]

No ideas on this? It's got to be easier to figure out than that strange thunking sound on stopping

 

[oldredrunner]

What do your spark plugs look like pull and check them and u mite as we'll replace them since u r at it

 

[giro]

What do your spark plugs look like pull and check them and u mite as we'll replace them since u r at it

I replaced those less than 10k ago, with the fancy Platinum ones since they were on sale.

I haven't had any starting issues except for when the engine is hot, but it has been 65k since I replaced the distributor. There's always a slim chance that it's something like that, where with a little thermal expansion the rotor doesn't quite hit the points.

But it seems much more likely that it's something else, some emissions control or something. OTOH, it must not be that common, since no one's chiming in. On the 3000gt board overriding the fuel pump relay was the most common "upgrade" of anything, and the fix for hot engine no-start issues. I was hoping for an easy obvious point in the right direction, but I guess our engines were just too well made

Any other guesses? When my wife hit this it was just when driving around town, possibly even before the thermostat was completely open. We are at 6200-7500', so air pressure is less and the boiling point is lower. But it's not just something around elevation, since the time I experienced it was after driving down to Sacramento.

 

[541joseph]

Easy way to tell. Pull the distributor cap off and see if its full of ozone (just look like white gunk on the top) if there is you have bad cap and rotor

 

[77'911]

First, if the EFI relay($12) has never been replaced on the truck, you might consider doing so. I would also get out the fuel pressure tester and check the running/rest pressures. You might consider dumping the plat spark plugs, they foul quite easily. NGK coppers are one of the most reliable plugs for these motors. The plug is usually below $2 a piece as well. When was the last time a fuel filter was done?
If the fuel system checks out to spec, I would then look to the starter circuit.
regards

 

[giro]

First, if the EFI relay($12) has never been replaced on the truck, you might consider doing so. I would also get out the fuel pressure tester and check the running/rest pressures. You might consider dumping the plat spark plugs, they foul quite easily. NGK coppers are one of the most reliable plugs for these motors. The plug is usually below $2 a piece as well. When was the last time a fuel filter was done?
If the fuel system checks out to spec, I would then look to the starter circuit.
regards

Thanks!

If anything was replaced, it would have been back at the toyota 3.0 rebuild campaign, now nearly 90k and 10+ years ago. Could be good to replace the fuel filter and relay (though in the past relays have started failing on me when cold, not hot).

I'm not too worried about the plugs right now, but if other things check out they can be on the list. Fuel pressure makes the most sense to me in this case, with electrical a close second. But it's tougher since it hasn't been consistent.

 

[pkinfinity]

Starter relay

I had the same problem. Solving it was a real PITA. After reading the blogs, I tried a relay to the starter. The problem has been solved for that last few years.

 

[giro]

I had the same problem. Solving it was a real PITA. After reading the blogs, I tried a relay to the starter. The problem has been solved for that last few years.

Can you elaborate on this a bit? Did you add a relay, or replace an existing relay? What does the relay do?

I replaced my starter a few years ago and haven't had problems with the starter since. But if there's a relay mixed in there that needs to send power elsewhere, especially if it helped with a similar problem, that would be good to know about.

Thanks!

 

[pkinfinity]

Giro,

I'm not an electrician. You can go to a good mechanic who will set up a relay wire directly from the battery to the starter.

 

[giro]

Ahhhh....I think this is something else. When this happened, the starter was getting power and running, but then the engine would stumble and such. It sounds like what you are talking about is that HotShot relay for pre 86 4runners.

But I'll look around at things. I'd first look at the relays (per you and '77), and then '77's other advice. Hopefully it won't be too tough.....though would sure be a lot easier if I had a 100% reproducible case.