1999 4runner limited 4wd starts but wont run

hello I have a 1999 4runner limited 4wd. Motor was just replaced but truck was doing the same thing with the old motor in it. The truck will start perfectly and run for about 5 seconds and then seems to run out of fuel and die. I have power to the fuel pump and have checked the efi relay. Took the gas line apart and when I turn the key to start I get plenty of initial fuel. Any ideas as to what could be the problem? Thanks in advance.

 

What got swapped over from the old motor to the new one?

Injectors? Intake? ECM?

Do you get any codes?

 

Mine had a plugged/broken catalytic converter. It had the same symptoms.

The "cat" looked clean and new. It flowed good on startup but then the loose stuff inside must have been forced against the outlet.

I also replaced the EGR vacuum modulator. It was visibly broken and would not operate the EGR valve correctly. Probably not your problem, right now.

 

Bullet, what engine are we talking about?

If he has a 3.4L engine...he does not have an EGR.

 

It was a complete used motor swap out minus the ECM. The old motor definetely had bad head gasket/cracked head with milky oil and lots of white smoke. The old motor also would start but only run a couple seconds. No codes. After the motor swap the new motor starts right up but does the exact same thing. Runs 3 seconds then shuts off. Sprayed carburator cleaner into air filter and it ran for about 40 minutes. Also still lots of white smoke out of exhaust which im hoping is from previous motor that got into the exhaust. Still no codes. Took fuel line apart and I get lots of gas when I go to start so pump has power and relay was tested and works. Took the fuel return hose apart then started the truck and never got any gas out of the fuel return line so im stumped as to what to do next.

 

and yes it is the 3.4 motor. Will the CAT smoke like that if its plugged up?

 

I don't think so. White smoke is either coolant or running really rich. Black or Bluish smoke is burning oil.

You sure they did the engine swap?

 

Yes my friend did the swap. Hes a pretty good mechanic but he is stumped as well...new motor put the smoke out almost immediately. Motor never got hot and coolant level didnt move. Its like we didnt change anything by putting the new motor in.

 

So after 40 minutes it's still blowing white smoke? That doesn't sound like the cat.

No overheating sounds like there's no blown head gasket.

How hard is it to disconnect the exhaust on these things? If it's disconnected, you should be able to see if the motor is making that smoke and to rule out the exhaust.

I'm kind of on the side that it's an issue with fuel injectors or the ECM.

What does the white smoke smell like? Sweet or gas? (don't kill too many brain cells)

 

Also...pull the plugs. What do they look like?

 

Yes the smoke seems to go away and then come back...when upping the throttle it comes out pretty thick but not every time. I dont believe it to be a head gasket either...temp guage stayed below center the 40 minutes that it ran. I may try to take the exhaust apart.. shouldnt be too hard as it was apart when motor was installed. I dont think its fuel injectors only because the new motor came with them and im still getting the same result as the old motor. ECM is a possibility for sure as it has never been replaced. As far as the smoke smell it really doesnt have the sweet smell to it....to me it just smells like normal exhaust but lots of smoke. Its been sitting for a year or two before we did the work and has a half tank of gas but even if that was bad I shouldnt be getting the smoke.

 

Pulling the plugs may be quicker to get at things. I know that's not hard on these cars. Compare them to what's in the link below:

https://www.championautoparts.com/P...-and-maintenance/how-to-read-spark-plugs.html

 

O2 sensors are also culprits for the car running rich. It should throw a code though.

Edit: also disconnecting the exhaust may throw the sensor out of range so not sure if what I suggested will work too well. I'm very old school with cars. I think I'd start back with the plugs and see if you can see fouling.

 

Thank you. I will do some more troubleshooting and let you know what I find.