Engine not running right and hard start

[1RangerNut]

I just swaped the bad motor in the 1990 with one that supposedly runs and came with the truck but can't get it running right.

While it was on the stand I put in new plugs, a cap/rotor, I cleaned the TFI and regreased it, put a new rear main, and valve covers.

You have to give it gas to start and when it does it has a miss to it and there is fuel/black smoke coming out the tailpipe but it seems to run smooth'ish if you romp on it.

Things I have tried are sea foam in the fuel tank and in the vacuum line, I checked the fuel pressure and have 30-32 at idle and jumps to 40 when vaccum line is unhooked from regulator, I put the wires off the old motor that looked newer, cleaned the throttle body, and hooked up the O2 sensor that I forgot about.


Does anyone have a clue what could be wrong with this thing?

It doesn't knock, the lifters are quiet, and the injectors tick just slightly.

Sorry for the long post and any help would be appreciated.

Thanks: Steve

 

[1RangerNut]

Anybody????

 

[adsm08]

Is there fuel in the vac system? Is the regulator vac line hooked up?

Also, when looking at a problem like this there are two big things to remember.

1) Black smoke is too much fuel and not enough air

2) When you hit the "gas" pedal, you don't actually give it gas, you give it air. Then the computer figures out how much gas it needs.

You have a definite over-fueling issue here.

 

[FireFighter431]

pull codes

 

[kimcrwbr1]

Did you replace the plug wires and what were the compression numbers before you installed it? Also check the fuel pressure after you turn the engine off and pull the vacuum line off of the regulator and smell for fuel.

 

[SenorNoob]

That sounds very similar to the way my 4.0 did right after the swap when I had the O2 sensor wired wrong. Probably not related but is the connector loose? Do you have a Check Engine light on? If so I'd start with reading the codes.

 

[1RangerNut]

No check engine light.

No fuel coming out of the vac line, like the old one does.

O2 sensor is plugged in but since I forgot about it might have melted on the exhaust some.

What about the computer or the map sensor on the firewall? Cuz it's kind of acting like the old motor minus the knocking.

 

[1RangerNut]

Old post, but turned out mice ate some of the computer wiring, so I replaced the pcm with a junkyard one and fixed the wiring.