293K miles '90 4Runner 3VZ

About a week ago, leaving work - engine 4 hours cold, I noticed the 4Runner was hard to start. Cranked about 10 cranks, then weakly fired, another 3 cranks, then caught and ran fine. Prior to this it had always caught on the first 2 or 3 cranks. Battery is great, cranking speed excellent.

When I arrived home (engine hot 30 minute commute) and put it in the closed garage, the wife noticed a strong raw gas smell. Both symptoms seem about the same regardless of whether the engine is hot or cold, although just shutting down for a minute to 5 minutes and restarting, it starts a bit better, but perhaps not as well as it used to.

I've only used it a half dozen times since this cropped up, but it's been fairly consistent and gotten no better.

After starting, it runs great on highway and city.

There is no leaking gas I can find, gas smell seems to be strongest at the engine compartment, not near the tank or exhaust.

I did a head job 9 months ago. Fuel filter is getting a bit old.
Any suggestions for tracking this down? Am I looking at flooding - perhaps Cold Start Injector problems? I'm not sure the gas smell is really a symptom, as it's not all that strong to me, but then I've had a cold for the last couple weeks. The wife thinks it's very strong.

Comments would be greatly appreciated.
Thanks!

 

So it's hard when its cold huh? try disconnecting the Cold start Injector, Then give it a crank.

 

Uhh if he does that itll just give the same symptoms..

You are on the right track though.
Id say take an ohm meter to the cold start injector time switch.
And then search.

 

Had the same problem with a 22re a while back. Turns out one of the O rings on one of the injectors failed. It would be hard to start after it sat for a while but would run great once it fired up, also had a strong smell of raw gas. After it was running I could turn it off and fire it right back up with no issues other than the smell but if it sat for more than about 10 minutes it took a few cranks to get running.

When the O ring failed it did two things. 1) it let the fuel rail lose pressure as it sat without running (like during the day at work or over night) and 2) it would let the injector squirt a very small amount of fuel out past the O ring while it was running (not enough that there would be a visible puddle but enough to smell).

My advice is to start it and look at the fuel rail(s), I've never messed with a 3.0 so I don't know if you can actually see the rail(s) and injectors without pulling something apart.

 

This is a great comment and really sounds like it might be right. The gas smell seems to increase for about ten minutes after I stop - that is probably the fuel leaking out as pressure drops and it sits. It's gone the next morning. And I've noticed I do smell it while it is running.

I have started and looked for a leak, specifically looking at the fuel rails, but they are pretty buried, so I didn't see much.

Do you think the hard start is because it takes some time to build up pressure in the rail? How could I get pressure maximized before trying to crank? If it starts easier with pressure in the rail before cranking it might help me confirm before tearing off the top.

Thanks!

 

If the raw gasoline smell is strongest on the passenger side on the engine compartment, you may want to grab a small mirror and a flash light to check the fuel pulse damper. It is on the end of the fuel rail near the firewall.

It is a metal mushroom cap that has a hole on the very end, inside the notch of the cap. Stick your finger into that notch and smell it for gasoline, if it smells like gasoline then the diaphragm inside the fuel pulse damper might be worn or torn. If so it needs replacement since it will leak fuel onto the crossover pipe.

So basically you risk an engine fire every time you drive it around regardless of the source of the actual leak but more so if it is coming from the FPD.

 

Thanks, I'll check this too. I plan to open it up this weekend.

This sounds like a good candidate, too. I found this comment doing some research (My 4Runner is 2nd gen):

 

I have a 92 pickup with a newer 94 3.0 i found quite a stream of fuel coming from the rear of the block on top just under the intake. i cant see real well to find out exactly but i suspect the cold start valve. does anyone know where i can find a picture of the back of a 3.0 diagram form would b nice but beggers cant be choosers.

 

Had the exact same problem as you, in my situation I had a leaking O-ring on one of my fuel injectors and the fuel damper was leaking, after getting these fixed the gas smell went away but I still have the hard starting problem. Good luck

edit* Also you can tell if the fuel damper is leaking it will leave a white chalky residue on the block you can see the fuel damper if you use a flashlight, its on teh passenger side close to the firewall.

 

I tried to see the damper, but the engine was hot, and I couldn't get back there. I just couldn't get the time to check later when it was cool.

I've seen instructions to force the fuel pump on (for testing fuel pressure) by jumping at the jumper block. I want to try this first to see if the damper is bad. I suspect it will leak visibly with the fuel pump on and the engine cold. I'd really like a test that will show me if any of the O-rings on the injectors need replacement.

My concern is that if I open it up, I won't be able to see what's bad, and I'll put it back together without fixing it. (Taking off the air plenum that covers the fuel rails is a pretty big job - lots of connections to pull and label - one I'm familiar with from the head job last year) I suspect I can figure out the fuel damper before I pull it apart, since I can get limited access there with a mirror when it's all assembled, but how do I identify if any of the injector O-rings needs replacement? So they leave a visible gas evaporation mark?

 

To turn the fuel pump on you jump th FP and B+ terminals and turn the ig to on.

 

Thanks a lot, I was in the middle of trying to find this info when I decided to check back here.

 

I've been delayed in working on this, but the air chamber is now off the engine. When I power up the fuel pump, fuel pours out of the fuel pulsation damper. Does anyone want to recommend a source for buying a replacement? Thanks!