1990 Bronco 2 2.9L V6
OK, Here is the symptoms my truck starts right up and idle's at 1200 RPM and idle's just fine with no fluctuation. While it is still in Park I press the gas pedal and it rev's just fine I am able to hit 4k+ RPM.
It is the same way in neutral runs good sounds strong.

BUT when I put it in either Reverse or Drive/OverDrive, I press the gas and it acts like it wants to stall out. But it doesn't stall out, it just stops accelerating just rumbles really low. Then soon as I let go of the gas it goes back to idling fine. I can drive the truck around the neighborhood while just barely giving it gas not to exceed 2k RPM and 25 MPH it seems.

I was told to try replace/repair a few things so I did.
Fuel Filter "Changed"
Fuel Pump "Changed"
O2 Sensor "Changed"
Catalytic Converter "Cleaned...."
Muffler "Changed"

Sorry if my Description is vague Ill try and take a Video or record sound tomorrow morning any input is helpful. This forum is my last hope/resort before I stick a rag in the gas tank and lit it.

 

Sounds like you've gone after the major things, but I didn't see fuel pressure regulator on there.

If I remember right, the FPR is on the fuel rail back towards the firewall, and on the driver's side. There's a vacuum line going to it. If you pull that line loose, and you see fuel seepage or where it's been wet, then your fuel pressure regulator needs replaced.

Another way to test is to hook up a pressure gauge to the Schrader valve (Looks like a valve stem) on the fuel rail. Then you start the engine and take a reading with the engine running. I can't remember what the pressure should read, but I think with the FPR unplugged or damaged, it should read higher pressure.

These systems like to push more fuel to the engine than is needed, and it dumps the unneeded fuel back to the tank to reuse again later. It's the FPR's job to determine how much fuel gets used and how much goes back to the tank.

If you don't mind me asking, how hard was it to pull your tank to replace the pump? I have a feeling I'm going to have to pull my tank to check for a leak. Thanks!

 

I looked for the fuel regulator and I didn't see one.

As far as the fuel tank goes it was easy the hardest part was actually the skid plate it didn't want to come off till I loosened up the tank straps but once I got the skid plate off I used a ratchet strap to hold tank up then took off the tank straps and then slowly released the ratchet strap till the tank hit the ground and unhooked the fuel line when the tank was still half way in the air...

 

I and if it was the FPR why would it only effect the truck when it's in reverse and drive? And not stall the truck when in neutral or park? I know it doesn't send as much gas to the motor but it should still affect the rpm should it not?

Sorry I'm still learning....

 

I am going to just go ahead and replace the FPS, but how do I remove the hose from it?

 

No need to feel dumb about asking questions. I feel dumb everytime something like this happens, until I figure out how to fix it. I've got a lot of fixing to do!

I think if the transmission is in park or neutral there's no load on it, so it will rev up almost like it should. When you have it in drive or reverse, that puts a load on the engine and that's when you find out things aren't working properly.


I've not seen a hose quite like that one before, and I'm a bit unfamiliar with the connection. My guess is that black fitting will squeeze together (shoving the bottom towards FPR) and then you can pull the whole thing off. The hose you already pulled off was the vacuum line I was telling you about. Sometimes the diaphragm in these goes bad and causes gasoline to leak up into that vacuum line. Did it, or the line itself appear wet inside?

I replaced the one on my 87 Bronco II which has a similar design. I think we ended up going with Advanced Auto Parts, but that was 2006 when the prices of everything was cheaper.

Thanks for the info on the tank. I'm gonna have to pull mine because if you fill it full, it'll start dripping gas and that bothers me. I didn't know how hard it would be to get up in there and get fuel lines and wiring loose, or if I could drop the tank halfway and THEN do it.

 

Now I can add 4 more things to the list and still not running right...

New Fuel Pressure Regulator 65.99
Distributor Cap 19.99
Cap Ignition Rotor 12.99
Throttle Air Bypass Valve 61.99
Ignition Coil 23.99

Please for the love of everything good and right in the world someone please help!

 

Before you drop your tank, check your hose from your fuel door to the tank mine broke and did same thing it leaked when I filled up.

 

So you've got a new fuel pump, filter (I believe the 90 only had one. Older B2's actually had two), and a new fuel pressure regulator. So you should be good on the fuel side, unless you've got some dirty injectors.

On the ignition side, you've got a new distributor cap, rotor, and ignition coil itself. The only thing I haven't read (and maybe I've missed) is spark plugs and wires.

You know the thing runs, so it does have spark and fuel. It just doesn't run well under load. I think the next things I would check is to pull all the spark plugs, and make sure they are clean and properly gapped. Then if that checks out and you have access to a timing light, I would hook it up and make sure that the timing is about 10° BTDC (per the Haynes Repair manual and my poor memory, so you might want to double check me on that!). Don't forget to remove the SPOUT connector or your computer will be adjusting the timing while you'll be trying to read it. On my 87, the SPOUT connector was a plastic connector hanging off the passenger side of the engine up by the intake manifold with two wires coming out of it.

I'll come back in a couple days and check on things and see if anyone else has helped you. The only other thing I can suggest is to buy a can of Seafoam or some kind of fuel injector cleaner and run that through the engine and see if that helps. It still seems to me to be either a spark or fuel-related issue.

Good luck!

 

Just wanted to drop a line. Haven't heard from you in awhile and wanted to see if you got the problem figured out. Hopefully so!

 

Still not running right updated replacement list

Fuel Pump
Fuel Filter
Fuel Pressure Regulator
Ignition Coil
Throttle Air Bypass Valve
O2 Sensor
Catalytic Converter
Muffler
Distributor Cap
Cap Ignition Rotor
MAP Sensor
Spark Plugs/wires

Could the TFI module cause this issue? or the Distributor its self?

 

Drop a 4.0 in it. You will just keep chasing problems with the 2.9

 

My 88 is having similar issues and I don't want to put the effort into it that you did because of the rust. Did you ever figuer out what it was?