OK, I know this is GM, but I also know we have some very good gearheads here that work on other brands as well.

My 1990 F150 is getting on my last nerve. It will stall out. Some times when driving, others when not moving. When driving it will clear out and go again because I leave the clutch out. But when not moving it will die. This video shows what happens.



I've already replaced everything on the ignition system, so that'* not it. It'* not fuel, because it'* flooding. Today I had a little extra time so I pulled it in the shop, it stalled 3 times. So I hooked up just about everything I had to monitor the engine next time it stalls. And, it runs for 20 mins with out a problem.



At this point I have 2 ideas. One, a clogged cat. But I don't have a vacuum tester, if I did I could test that. The other is the EGR valve. When it ran the long time I had forgotten I unplugged the EGR. But that'* $87 and I'm not changing that on the off chance that'* it. I'll just unplug it. Thoughts? Ideas?

What motor is in it? The 302 v8 or 300 I6?

You can try testing the cat by drilling a hole in front of the cat, and if it runs smoother with the hole open than closed, it could be plugged. You can then weld the hole shut, or use a sheet metal screw to close it.

Have you tried going to a JY to see if you can get another EGR? I know it may not be reliable, but it sure beats paying $87 for a new one, only to find out it was fine all along..

I'll try drilling a hole, just odd that it'* not all the time. And I can't remove the cat without cutting it off.

I may just cap off the EGR and that will be that. Not like I have to pass emissions.

The engine is a 5l v8

Those engines used to have a prob with the fuel press regulator failing and letting the vacuum suck the raw gas into the top of the plenum. Check out the routing of the vac hoses, and you will see how it can happen.

I checked that, no gas smell in the vacuum lines.

Did the tach jumping start around the same time?

Most of the times it stalls the tach will jump like that and the fuel pump acts weird. Today I capped off the EGR tube. I disconnected it at the exhaust pipe and capped it there. I started it and it ran. It stumbled real bad for a few seconds, but never stalled. Then it ran fine again. I may have to unplug the EGR, but then I'll have a engine light. Another option may be to pull the solenoid off the top and leave it plugged in. A plugged cat is the only other thing I can think of.

i dont know much about fords but i dont think the cat would cause the tach and fuel pump issues. where does the tach signal come from ign control module? you sure you got a good one and the engine and where ever the fuel pump grounds has a good clean path to the battery neg?

hmm just a shot in the dark, I'ld first start testing for vacuum leaks (carb cleaner, spray it all over your intake system see if you get any response), definitely get an actually fuel pressure reading to clear the pump and TPS as a problem, also not a very well known issue but testing your harmonic balancer(crank sensor) might be wise, kind of a pain in the *** seeing as you have to pull the crank pulley 99% of the time but has saved me a whole lot of troubleshooting hours more then a few instances. Keep us updated

Already checked for vacuum leaks, tested fuel pressure, and problem happens with both tanks, each has it'* own fuel pump. Tested TPS, no crank sensor, truck has a distributor. I still need to get in there and start looking over the grounds.