Bronco II won't restart when hot

[JMilton]

My 1988 Bronco II 2.9 will not restart when hot.
First thing I did was change the TFI. Didn't fix it. Then I changed EEC, coil, distributor, plugs and wires, cap and rotor, TFI again which didn't fix the problem. I don't know where to go from here.

 

[Tedybear]

Air Fuel and Spark. (Timed correctly of course)

What exactly is happening and when? How long after you run it and stop does it take to restart?

Do you hear the fuel pump doing it's thing when you turn the key to 'on' when it's in this state?

If you remove a spark plug wire and insert a spark tester, does it have a strong spark?

S-

 

[meskater132]

My 1990 BII

1990 BII 2.9l wont restart when hot either i tried re timing her and nothing, can hear fuel pump running, takes 20min to restart, found if i disconnect the batt and tap the two leads together tends to clear up issue which leads me to believe ECU issue

 

[Gilbee01]

The ecu is you problem ( had the same issue) also remember that the heating issue can be fixed by swapping out the radiator from a 3.0explorer or by buying an aluminum one. Also look at both fuel pumps and filter if the tank pump is going out you may not be getting enough pressure to start.

 

[bIIjr]

My 86 does same thing drives me insane

 

[RonD]

Just to test if it's spark or fuel, get a can of starting fluid(ether), next time you have a no start pull off the PCV valve hose from the intake, spray some starting fluid in and replace hose.
Try to start
If it fires then dies, no fuel is the issue.
If it doesn't fire, then no spark is the problem.

If it doesn't fire try cooling off the TFI module on the side of the distributor, if it starts up then you found your problem.

The module can get too hot on these TFI systems, even a new one, just a bad design in locating them.
Read here for a fix:
http://www.therangerstation.com/tech_library/remote_tfi.htm



Often wondered if you couldn't install a small 12v fan at the front of the engine bay and a flexible duct back to the distributor, basically a cold air intake for the TFI module, lol.

 

[JMilton]

Here's where I've gone since there. Bought a spark tester. When she dies and won't restart I have a good strong spark. Now though when I try to restart, it back fires through the intake. The idle also surges from running good at 900rpm to about to bog out, and it will bounce between them for upwards of 10 minutes before ultimately it stalls. On some occasions I can hear it misfiring and a loud backfire in the d/s exhaust manifold. I have also just replaced the cap, rotor, distributor entirely with new TFI, plugs and wires again. I held a timing light in the timing while it was surging. The truck sat at 10 btdc and didn't fluctuate with the surge in idle. However I could see it bouncing quite a bit on occasion. I am confident that I do not have a bad EEC. I bought a new one because that's what I thought it was. But I kept the old one as well. I have since tried both EEC modules in a buddy's bronco II and they work perfectly fine. I am totally baffled by this crap and am coming to the end of my rope with this truck.

 

[chazzone]

codes?

 

[JMilton]

Codes found

KOEO - cold - no codes
KOEO - warm - DTC 44 o2 always lean

Today after this I installed , new tps, cool temp sens, iat sensor , o2 sensor.



I also recorded a video of it for your viewing pleasure. Btw today it restarted 3x when hot.
http://youtu.be/e-q2Y0_BexQ

 

[Gilbee01]

Glad you got it working again and hope the little back fire issue clears up.


-gil-

 

[chazzone]

You didn't mention the misfire/backfire in your first post. It's entirely possible that that is a separate issue from the lean/hard start problem. Double check the wire placement. Did you check timing with the spout out?

Nether would cause the lean condition, but they could be contributing to the misfire.

I'd throw a vacuum gauge on it, too.

The hot start issue is usually a coolant temp sensor. You might not get a code, but you could check values on the sensor.

 

[JMilton]

Here's where I've gone since there. Bought a spark tester. When she dies and won't restart I have a good strong spark. Now though when I try to restart, it back fires through the intake. The idle also surges from running good at 900rpm to about to bog out, and it will bounce between them for upwards of 10 minutes before ultimately it stalls. On some occasions I can hear it misfiring and a loud backfire in the d/s exhaust manifold. I have also just replaced the cap, rotor, distributor entirely with new TFI, plugs and wires again. I held a timing light in the timing while it was surging. The truck sat at 10 btdc and didn't fluctuate with the surge in idle. However I could see it bouncing quite a bit on occasion. I am confident that I do not have a bad EEC. I bought a new one because that's what I thought it was. But I kept the old one as well. I have since tried both EEC modules in a buddy's bronco II and they work perfectly fine. I am totally baffled by this crap and am coming to the end of my rope with this truck.

Here's where I posted the miss. It's not shown in the video, but the truck starts fine, will run for 2-3 minutes, then backfire for 3-5 seconds, then level out for 2 minutes and repeat. I do thinkits unrelated from the hot-start but that's my current issue.

 

[Gilbee01]

Don't know why but just a wired thought. Did you retime it after changing all the sensors? And I remember something about 10 over. For the 2.9. Here is a link to a picture on how to time it properly in the 2.9

-gil-

 

[JMilton]

After your post I did check the timing, it is spot on 10 btdc. When I reconnect the spout it goes from 10 btdc to roughly 35 and bounces between there. However I the removed the spout again and let it run and the same symptoms occurred. On the flip side, the "wont restart when hot" problem is completely gone.

 

[Gilbee01]

Did you set the timing , turn off the inhibition all the way, reconnect the vac. And then turn back on and check the timing?


-gil-