I am working on a 2.9L V6 in a 1989 Bronco II 4x4. I know this truck inside and out. I've had the motor out and replaced all the seals and painted it all up. I swapped out the electric shift t-case and put in a manual case, then swapped to manual hubs. I took out the crappy FM-146 and put in a M5OD from a newer ranger. So yeah, I have replaced about everything once and I know a lot about the vehicle..

I am however, stumped on this issue.

The truck will fire right off when it is cold and has not been run for a while. However, once it has been run and left to sit for say more than 15 minutes and tried to start it will just crank. I have to crank it at least 2 sometimes 3 times before it will catch and fire, and then when it does it the whole truck shimmy's for a few seconds!

I thought maybe I had leaky injectors so I pulled those out and had them rebuilt. Problem still exists, so I just changed the fuel filter.. nothing!

What am I missing here?!

I hate driving the thing because of this cause everytime I stop and go somewhere it sounds like crap when I try and leave! But it gets 17MPG, and the F-250 only gets 10-11 so I would REALLY like to drive it!

 

After running the engine, check for fuel in the vacuum line to the fuel pressure regulator. Fuel in line=bad FPR. This seems to be a somewhat common cause of rough warm starts.

 

Pull the codes and see what it gives you.

 

Another problem might be that the TFI module is getting hot and/or your cap, rotor, wires, and possibly the plugs are due for a change.... your engine could also have enough wear on it that the rings are about ready to be replaced as well... or even the valves have some blow-by. I have a similar problem, but I haven't taken the time or made the decision to spend the money on rebuilding the engine yet.

Also, you usually have to turn the engine over for about 30-60 seconds on a hot-start and let the key return to the run position, or it will usually not fire... or fire and eat your starter. Cold starts ... usually you can kick the key over for 5-10 seconds and let it return to run and it fires right up no problem... especially on a high-mileage engine. That's just my $0.02

 

Mine will fire within a second of cranking when cold. When I say warm, I can run it for 2 minutes before it even heats up, and try and start it an hour later and it will have to crank for 10-15 seconds before it catches. It was never like that before. The basic tune up items have been changed not too long ago.

 

Another thing you'd want to check is make sure you don't have any holes in your intake tube. This can cause weird issues. I have a similar problem and aside from doing a code scan, I have checked and/or replaced -everything- other than all the sensors, etc., and can't come up with an exact cause. I'll probably go and get a cheap scanner pretty soon and see what comes up. I do know that my fuel pressure regulator was changed within the past two years... and I don't think it's already failed again. I think this weekend I will tinker around with it some. I'll probably check the fuel pressure and the regulator. Wouldn't surprise me if my injectors are in need of replacement or overhaul, too.

EDIT from previous post: I meant 10-20 sec. instead of 30-60... 30-60 sec would be severe worst case scenario, etc.

 

Mine did the same thing.Clean the TB real good and check the IAC valve,mine was bad and would not idel right.Replaced the IAC vavle and cleanes the TB,startes and runs like new.

 

I had the same problem with my 86 b2 a while back.. i replaced the fpr and new iac valve..that fixed it..i think it cost me around $50 for the parts.no starts right up every time