99 Tacoma 3RZ Cold Start Issue

the_white_shadow

the_white_shadow

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I working on a friends 99 tacoma with the 2.7l 3RZ 5-speed. It will not cold start to save its life. I have to crank and crank forever and with the pedal floored to get it to start. Once its warm, it runs fine and you can start it without issue. But the next day we are back to cranking.

Back story. Truck sat for a few years after a family member passed away. Rats ate the plug wires and the cruise control wiring on the passenger side at the firewall. I got it a few months ago and did a complete tune up on it with the normal stuff. plugs, wires, fuel filter, etc. Was hard to start then, but not as bad as now.

I have done the following to it to try to fix the cold start issue.
1. Changed MAF with known OEM working one
2. Changed throttle body and IAC with known working one (cleaned the TB while it was out)
3. New fuel pump
4. No CELs
5. Changed FP regulator
6. Changed intake boot with new un-cracked one
7. Pulled and cleaned new spark plugs (they were wet)
8. Verified ECT sensor on back of head was working fine with scan tool. No weird values or anything to mess with the ecu.

Still wont cold start. Tried it again this morning and nothing. Only thing left to check are the injectors and the ecu. Im thinking the injectors are leaking down overnight and are filling the cylinders with enough fuel to not want to start. Engine oil looks fine and not at an elevated level. I have another stock set from another engine im going to try. I can smell fuel under the hood during these cold starts. Next will be the ECU. I dont think its the ecu as it runs perfect once its warmed up.

Thoughts on what to try next?
 
no advice - mine is similar but not as bad. I think mine is losing fuel pressure when sitting.

following.
 
rockota said:
no advice - mine is similar but not as bad. I think mine is losing fuel pressure when sitting.

following.
Click to expand...
I thought that might be the case which is why i installed a new pump. But as soon as you crank these the fuel pump turns on and you get instant fuel pressure so im at a loss here. running out of **** to try.
 
Update. Injector changeout did not fix. Can still smell raw fuel when cranking. Not getting fire it seems when cold.
 
get a spark tester, 99 should be twin coil. go from there. wet plugs typically indicate lack of spark. also try key on engine off for 15 seconds and observe check engine light functionality. you may have to give it a bit to "wake up" (the ecu). i forget which triggers spark the cam or crank sensor.
 
Another morning and another hard hard no cold start. Changed the oil yesterday because it looked bad. Seemed to help at the time but not this morning.

Tried a different ecu. No change.

Can smell raw gas while cranking. Tries to barely fire. Seems to have a lot of combustion in the radiator even when cold. Makes me think blown head gasket partially that heals when warm. No fluids mixing where they shouldn’t be as far as I can tell.
 
Not sure if this is any help. I had a 3.4 in a Tacoma that sat for a few years. Had the same sort of trouble. Ended up having some valves stuck open. Is it possible you have some that are sticking cold and finally breaking loose after cranking a while and warming up? Might be worth a compression test.
 
mightymouse84 said:
get a spark tester, 99 should be twin coil. go from there. wet plugs typically indicate lack of spark. also try key on engine off for 15 seconds and observe check engine light functionality. you may have to give it a bit to "wake up" (the ecu). i forget which triggers spark the cam or crank sensor.
Click to expand...
I’ll give that a shot. I have some other coils on another truck that I know are good. It’s weird that it only does it when it’s cold. Once it fires up you can start it every time.
 
Pless said:
Not sure if this is any help. I had a 3.4 in a Tacoma that sat for a few years. Had the same sort of trouble. Ended up having some valves stuck open. Is it possible you have some that are sticking cold and finally breaking loose after cranking a while and warming up? Might be worth a compression test.
Click to expand...
I’ll give that a shot. Thanks.
 
Pull the hose off the fuel pressure regulator and see if it's leaking fuel past into the intake. You can pull it off at night and cap the vacuum port and see if it cold starts ok, or the line drips at all. I've seen FPR's bad enough you could just pull the hose off while it ran and it fuel would run out, If it's starting when the pedal is held to to floor it's in clear/flood mode and likely is over fueled. It can also be caused by injector leak down however, you already swapped injectors. That at least reduces the chance of that although 2-3rz engines are kinda common for injector issues.

If you think it has a head gasket issue. Disable the fuel system so it runs out of fuel pressure and shuts off. Leave it disabled over night and check the cylinders the next day, You can pull the plugs and toss a endoscope in the cylinder or crank it(fuel disabled remember) and check the plugs for coolant. Although I'd think if this is the issue you would smell and possibly see the cloud from it burning coolant.

Ignition issues are unlikely unless the battery is such low voltage it hardly cranks. Rarely is there a primary or secondary ignition issue that causes cold start issues without other notable issues. Typically ignition issues get worst with heat not cold.

I don't remember off hand what data those PCMs see, Cold unstarted check all the temps against each other, Coolant, air intake, ambient if it sees it should all be real close to each
 
94toytruck said:
Pull the hose off the fuel pressure regulator and see if it's leaking fuel past into the intake. You can pull it off at night and cap the vacuum port and see if it cold starts ok, or the line drips at all. I've seen FPR's bad enough you could just pull the hose off while it ran and it fuel would run out, If it's starting when the pedal is held to to floor it's in clear/flood mode and likely is over fueled. It can also be caused by injector leak down however, you already swapped injectors. That at least reduces the chance of that although 2-3rz engines are kinda common for injector issues.

If you think it has a head gasket issue. Disable the fuel system so it runs out of fuel pressure and shuts off. Leave it disabled over night and check the cylinders the next day, You can pull the plugs and toss a endoscope in the cylinder or crank it(fuel disabled remember) and check the plugs for coolant. Although I'd think if this is the issue you would smell and possibly see the cloud from it burning coolant.

Ignition issues are unlikely unless the battery is such low voltage it hardly cranks. Rarely is there a primary or secondary ignition issue that causes cold start issues without other notable issues. Typically ignition issues get worst with heat not cold.

I don't remember off hand what data those PCMs see, Cold unstarted check all the temps against each other, Coolant, air intake, ambient if it sees it should all be real close to each
Click to expand...
Thanks. I’ll give that a shot. The FPR was changed with another used one off a running engine. No change.

When I changed the oil last night it started right up and vapor came out the exhaust for a good 5 mins. Then this morning, oil still looked new and it didn’t fix things.

I’m getting a pending misfire code now on cylinder 1. Going to try different good coil packs and see if it will move around to different cylinders.
 
Good luck with the fix. I had a 94' 5.0 F150 that did this. Turned out it was the coil. Had this issue a second time with the F150 and it was moisture in the distributer cap, but 99 Taco's don't have distributers.
 
This is after 45 secs of cranking to get it to start with the pedal floored on and off. Engine is cold.

Second shorter vid is after 10+ mins of idle. Still smoking.
 

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94toytruck said:
Did the exhaust smell sweet too like antifreeze? Sure AF looks like a leaky HG
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Yeah. Best I can figure now is overnight coolant leaks onto a cylinder or two causing it to hard start. Going to pull plugs and let it sit and see with a light (no bore scope).

Also did one of them color changing tests at my friend who is a mechanic and it instantly changed colors.
 
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