HELP!!! Bronco II Problems

[edselman]

I have the 1986 bronco II back again, so I can learn how to drive. However, I have a problem with it. In the morning, (or whenever) I go to start it, it starts up fine. If I come back to it though when it heats up, I can sit there for about 15-20 seconds, until it turns over. It will stumble a little, then roar, and we are ready to go.

Does anyone know what this is doing? I did replace the TFI Module, that works great now! However, this problem has me confused.

I will appreciate all the help you can give on this problem!!

Dane

 

[jimbo74]

sounds like vapor lock

 

[glfredrick]

You likely have leaky seals on the fuel injectors. It is bleeding off all the pressure between starts, casuing both a rich condition in the motor and the need to re-pressurize the system before starting.

Quick fix - try turning the key to the run position until you hear the fuel pump stop - then turn it off and do it again, then start the engine. Should start OK.

 

[410Fortune]

Dane,

You mean since you replaced the thick film integrated ignition module it has worked fine ever since?

With the 2.9L EFI you want to do the following:
Keep a spare TFI module in the glove box, with the finger tool needed to access it and also some of the white lithium grease.
The TFI module is mounted on the distributor to read the ignition timing and tell the computer what is going on. the problem is heat kills them and the distributor on the 2.9L is right where it gets hot!

You need to start with a tune up, plugs, wires, distributor cap and rotor, fuel filter, air filter, clean the IAC valve, clean the throttle body, check the vacuum lines, reset the computer. Check the base timing with the timing pil removed, even scan the computer for any codes. If the problem persists you can check the fuel pressure, you can check the cat converter and you can check the 02 sensor and TPS sensor,

Sounds overwhelming I know, but its not that bad really. The 2.9L is an extremely reliable and logn lasting engine if you keep it maintained and in a good state of tune.
Bottom line is the truck is an 86 its bound to have some problems, especially if they are left for a long period without much attention.

You can listen to BOTH fuel pumps too, there is a low pressure or boost pump in the gas tank and a high pressure pump on the rail, in a BII if the low pressure pump goes out or ggets weak it will still run 90% of the time, until you park it on a hill.
The quickest way to diagnose a fuel delivery or pressure problem is to test the fuel pressure at the rail and check the power circuit (fuse and relay), then listen to the pumps for a whirring or sucking sound that just doesnt sound right.