'92 Won't Start: Needs 30 minutes between running

[kiddynomite]

Hey guys, I think the title sums it up fairly well. My Cruiser runs like a top on the first ignition. Runs fine on short and long trips, but once I cut it off, it won't start again for 30-45 minutes.

It turns over but I never get ignition. Seems like a sensor, if it was fuel pressure or ignition it wouldn't start at all, but not sure where to start. Any ideas?

Oh, one other thing, if I give it a 30-45 minute break between run times and try the ignition it cuts right on and runs just fine.

Thanks guys!

 

[Mark W]

What engine?


Assuming that it is not fuel or spark is erroneous. It pretty much has to be one or the other.


Mark...

 

[kiddynomite]

Mark,

It's an fj80 - stock everything.

I guess my wording wasn't very articulate so let me try and reword this My fuel pressure checks out fine and I'm getting spark - not only on first start, but when this happens as well.

My first thought was - gott'a be an EFI sensor or something similar because it's pretty clearly a mixture / temp thing. However a friend of mine, who is a mechanic, told me to check the o2 sensors too because Toyota's tend to have similar problems when the 02 sensors start to fail.

Any of this sounding like a good direction to go in?

 

[Mark W]

I was not sure what engine you might have because this is posted in the '90s section, not the '80s section.


In you '80, if you have fuel delivered to the cylinders and you have spark... it will fire. If you have a poor running situation then it would be time to look further. But if it is not firing off when you crank it, either you do not have fuel or you do not have spark.


Faulty O2 sensors will not prevent the rig from starting. Off the top of my head I can not think of a single sensor in the rig that will keep it from at least trying to start and stumbling a bit until you release the key. and only one sensor that will do that much even.

How did you determine that you had fuel pressure when you are trying to start the rig and it will not?


Mark...

 

[kiddynomite]

Ah!!! I guess when I was searching for solutions through the forums I never backed out to the right section - sorry for the confusion. (Any mods out there? Can you move this to the 80's series please? Sorry for the mix up)

As for the fuel pressure - I've checked it with a fuel pressure gauge and tested spark by pulling a plug and turning it over and seeing spark. I've tried removing the gas cap to make sure it wasn't a vapor lock issue and I also removed the mass air flow sensor to make sure it wasn't that either.

It tries very hard to start, it turns and turns and turns but never fires. Never rumbles or grumbles like it's about to ignite either. But on the first start it's a quick, clean, immediate ignition.

I'm stumped man...

 

[Mark W]

You can not get vapor lock in a rig with an electric fuel pump located in the tank. If you have fuel pressure when cranking, and you have spark, My first thought is that the injectors are not firing. I *have* seen overfueling result in hard/no start too, but I don't expect this is the case. To be sure, pull a plug and inspect if during one of the fail to start episodes. See if it is dry or drenched in fuel. Also note of the rig stumbles and blows black smoke when it does eventually start.


Mark...

 

[jonheld]

Sounds like faulty fuel pressure regulator to me. If you're getting spark and fuel to the rail, it's possible the pressure is too high. Fairly common problem for hard hot starts. Also look at the fuel pressure damper on the firewall side of the fuel rail. It should have a plastic cover on it with a set screw inside. Pop the cover and make sure the set screw is still in place. DO NOT ADJUST. NO USER SERVICEABLE PARTS INSIDE. If the set screw is out, then the unit needs replacing.

You should also check to see if the cold start injector is firing when it shouldn't be. Be SUPER careful as you can spill fuel on the hot manifold. I don't recommend this. Simply unplug the connector on the CSI next time it fails to start. See if it makes a difference.

 

[Mark W]

First determine if you actually have fuel to the cylinders or not. It is more likely that you do not, than that you are having an overfuel situation.

Once that fact is determined, then you can move forward without chasing multiple theories as to what the problem is.


Mark...

 

[kiddynomite]

Thanks guys. I checked the plugs like you suggested Mark and they were dry as a bone and a white/ashy color suggesting it was hot/lean.

Let me back up a few years. I had my cats replaced with aftermarket OEM cats because the factory cats were way more expensive than I could afford. When I did it, the guy told me my check engine light would stay on because they were after market - valid or not I took his word for it.

Fast forward to now - I almost forget about the light being on. I ran the diagnostic checks last night and got the codes (Rookie mistake I know, but like I said, it skipped my mind because it's always on). It threw 3 error codes.

1. Main 02 sensor (It's thrown that error since I got the new cats and has been replaced. I've always assumed it was a result of the cats)

2. Intake air sensor temp censor.

3. Mass Air Flow sensor.

So that's some more food for thought. I'm looking into picking up a new MAF tomorrow from the dealer.

 

[Mark W]

Don't throw parts at your rig until you kow what the real problem is. That can get expensive.

The MAF can be completely unplugged and the engine will still attempt to start so long as the key is turned to the start position. It will stumble and fire and overrun the starter until the key is released. So it is doubtful that the MAF is the problem here

The cats will not cause a false O2 sensor code. The cats are downstream of the O2 sensors.


I would revisit the fuel delivery aspect. it seems as if you are nit getting fuel to the cylinders. Where exactly and how exactly did you connect the fuel pressure gauge to determine that you had pressure.


Mark...

 

[jfz80]

x2 on how you checked fuel pressure? thought you needed an sst for that on the back of fuel rail
I know the fuel pressure tester I bought for the 2F would not mate up the fuel rail.

+aftermarket cats should not trigger the CEL-- one o2 before cats and one behind cats
i have a custom exhaust routing and aftermarket cats for 3 yrs with zero issues or CEL

+I have a MAF in NC if you really want to try it, pretty sure I can beat the dealer price

best of luck, youve got good advice so far, esp for being in 90's tech
(there are some hot no start threads in 80's tech i do believe)

 

[kiddynomite]

Last night I removed the MAF and checked it with a volt meter per the instructions in my Haynes manual. 2 of the 3 reading were incorrect and after reinstalling the MAF, it stalls on acceleration. It cuts on and runs fine, but once you give it gas it stalls.

I reset the codes, ran it for about 15 minutes and still the same problem. I'm going backwards and it would appear, even if it's not to fix this issue, the MAF needs replacing.

Jason, I'm in South East VA, where in NC are you? I might be able to drive down there faster than ordering one and having it delivered if the price is right. And too, I would rather give my money to a guy from these forums than some big company.

 

[kiddynomite]

One thing that's bugging me and was hoping you guys might know. I have, in the past, been able to take my MAF apart, pull the sensor and clean it with an electric connector cleaner and had AWESOME results. Part of the reason I pulled mine last night was to clean it but as I started to pull the sensor out of the housing I immediately knew it wasn't the same hot wire* setup I've worked with before. I also am pretty sure that's why the MAF is totally busted now.

Is it possible to clean this style of MAF sensor? I have never seen it before.

 

[jonheld]

You have an AFM on a 3FE motor and you screwed the pooch if you tried toremove the connector from the housing. Depending on the internal damage, you may be able to re-solder the connections back in place, or you may need to pick up a used unit. Any AFM from a 3FE will work. FJ62 through FJ80. This thread should also be moved to the 80 Series forum and you should spend some time searching on it. Tons of good info for you.