Rough running 2.9l

[NM_Broncoii]

Just finished up putting a newer motor in my 1988 bronco II same 2.9 as original. I put a entire new wiring harness,clutch,transmission and switch to a manual transfer case. It turns on fine and idles fine but if I have the map plugged in it will have no throttle response at all and will die if left open throttle. I’ve tried swapping to a known good one and still does that same thing. If it’s unplugged it does run a lot better. No codes at the moment.

 

[rusty ol ranger]

Just finished up putting a newer motor in my 1988 bronco II same 2.9 as original. I put a entire new wiring harness,clutch,transmission and switch to a manual transfer case. It turns on fine and idles fine but if I have the map plugged in it will have no throttle response at all and will die if left open throttle. I’ve tried swapping to a known good one and still does that same thing. If it’s unplugged it does run a lot better. No codes at the moment.

Check to make sure the vacuum line running to the MAP isnt leaking....and the port it plugs into on the manifold is getting good vaccuum and not plugged.

 

[NM_Broncoii]

Check to make sure the vacuum line running to the MAP isnt leaking....and the port it plugs into on the manifold is getting good vaccuum and not plugged.

It’s getting great vacuum and doesn’t seem to leak. Just weird because before I swapped motors everywhere worked perfectly. I’m wondering if maybe I missed a ground somewhere while doing the wiring. The wiring harnesses I got had multiple maps and doesn’t seem to matter which one I use. Also checked my fuel pumps and filters and drained the tank put brand new gas in it.

 

[rusty ol ranger]

It’s getting great vacuum and doesn’t seem to leak. Just weird because before I swapped motors everywhere worked perfectly. I’m wondering if maybe I missed a ground somewhere while doing the wiring. The wiring harnesses I got had multiple maps and doesn’t seem to matter which one I use. Also checked my fuel pumps and filters and drained the tank put brand new gas in it.

And youre 100% sure that other map is good? Im not great with wireing but i would think a ground would cause other issues aa well

 

[NM_Broncoii]

And youre 100% sure that other map is good? Im not great with wireing but i would think a ground would cause other issues aa well

Honestly no not too sure it was from a ranger aswell not sure if that makes a difference. Motor and wiring harness came from a 2wd ranger. Maybe I’ll start with a new map first then go from there. Sucks finally got it all together after 3 1/2 of working on it and just don’t run quite right. It was a shell when I picked it up

 

[rusty ol ranger]

Honestly no not too sure it was from a ranger aswell not sure if that makes a difference. Motor and wiring harness came from a 2wd ranger. Maybe I’ll start with a new map first then go from there. Sucks finally got it all together after 3 1/2 of working on it and just don’t run quite right. It was a shell when I picked it up

I totally get it. Im not sure but if that MAP came from a 4 cylinder truck it wont work on a 2.9. Im not even 100% sure if a 3.0/4.0 one will.

 

[NM_Broncoii]

I totally get it. Im not sure but if that MAP came from a 4 cylinder truck it wont work on a 2.9. Im not even 100% sure if a 3.0/4.0 one will.

Update I got the code for the map sensor to go away I had a orange ground wire hanging by the cylinder head I had to connect. Still was doing the hesitation so I blocked off the fuel return line and ran great. So I’m assuming fuel pumps are old and weak?

 

[rusty ol ranger]

Update I got the code for the map sensor to go away I had a orange ground wire hanging by the cylinder head I had to connect. Still was doing the hesitation so I blocked off the fuel return line and ran great. So I’m assuming fuel pumps are old and weak?

More then likely yes. Get a fuel pressure tester. Should be right around 40psi.

 

[tw205]

Update I got the code for the map sensor to go away I had a orange ground wire hanging by the cylinder head I had to connect. Still was doing the hesitation so I blocked off the fuel return line and ran great. So I’m assuming fuel pumps are old and weak?

Check the fuel pressure regulator if blocking the return made it run better. Pull the vacuum line off it and check for fuel in it.

 

[NM_Broncoii]

More then likely yes. Get a fuel pressure tester. Should be right around 40psi.

Got a new high pressure fuel pump and low pressure in tank and it still turns on then dies right after.

 

[rusty ol ranger]

Got a new high pressure fuel pump and low pressure in tank and it still turns on then dies right after.

But itll run with the return line pinched?

 

[NM_Broncoii]

Check the fuel pressure regulator if blocking the return made it run better. Pull the vacuum line off it and check for fuel in it.

No fuel coming out the pressure regulator and even when I replaced both pumps today acts the same. If maps attached and I block the return line runs pretty good and doesn’t die. If it’s attached and doesn’t have return blocked it runs idles high then dies

 

[NM_Broncoii]

But itll run with the return line pinched?

Yeah only if the map is attached to vacuum then I have to plug it but with it not attached it runs fine without return blocked.

 

[rusty ol ranger]

Yeah only if the map is attached to vacuum then I have to plug it but with it not attached it runs fine without return blocked.

WTF?

If youre 1000% sure that map is good only other thing i can possibly think of would be possibly the igniton module, alot of things depend on that for information

 

[NM_Broncoii]

Also thing is I’m getting no codes but a code 11 which I think means everything is working