Aight guys, this is the deal, looking to see if anyone comes with any ideas I haven't tried yet.

87 F150, 300 I6, 4 speed manual.

Starts, and runs, but will die suddenly (maybe after 15-20 minutes). This has been going on for a WHILE, but it seems to die even quicker now. As in I won't get any jerks or anything, she'll just quit on me. I coast down the road and as soon as I hit the clutch the RPMs drop to zero. I'll let it get down to 10MPH, put her in second, release the clutch and she might just start haha.

I'm not losing spark, timing light proves that. I'm not losing fuel either. Truck passes a vacuum test, but I'm still wondering if it looses vacuum after driving.

Only code I had so far was code 32 KOEO. Replaced EVP sensor after it failed a resistance test, and also replaced the solenoid. The valve tested fine as well. But...I tested it cold, not hot. Truck died again with new EVP sensor installed. And still throwing that same code. I got the truck to not die by disconnecting the old EVP sensor and disconnecting the vacuum line to the EGR. There was no CEL while I had it setup like this.

If I did it correctly I got a code 11 KOER. I'll be trying that again soon though.

Last note, if you drive the truck for a little bit, shut it off, let it set for a few minutes, then start it again, she'll have a bouncing idle characteristic of a vacuum leak. Rev the truck, it disappears. I want her reliable ASAP.

 

A truck with a vacuum leak will usually just have a high idle, not a bouncing one. And it won't usually stall on you like that.

To me it sounds like your ignition module is failing. I know you said you have spark, but an engine needs air, fuel and spark to run. Spark is usually the cause when you are already running down the road. Make sure you replace it with one of the same color (gray/black).

 

My idle is right about 890. Higher than spec yea, but vacuum gauge is in the green, around 20 in Hg. The truck won't really retard timing any lower than whatever I set it too. Advances fine, but I have never had it idle in the spec range.

I replaced the distributor (the dizzy straight up died on a trip to NC) with one from an Econoline van. Gray module on that one, gray module on my old dizzy that I bought and replaced the original module that I bought the truck with.

A few days ago I took the module off and put on one of my old ones and the truck dies regardless which one I have on it. Both past all tests in the Haynes Manual.

 

Ever thought about the idle control? too much air could cause death, but you said that you checked the vacuum. Is there a way that you could check the vac when it dies? I mean, vac gauge or something similar. Could the ecu be getting confused if your vss, or the vss sender (?), stops giving a signal?

 

New IACV is on the truck. Only way I'll be able to check vac is hooking up my vac gauge and running it into the cab. I might just have enough hose to try that. The one firewall inlet that I could use is used for my subwoofer power wire haha, might find another or just figure something out.

 

Does it start right back up after it dies?

If your warm idle is 890, something is wrong. What is your base timing set to?

 

Well I did a little fiddling today, found out some things. Firstly, I drove the truck to work with the vacuum hose from the EGR solenoid to the valve disconnected. No dying whatsoever. I got home and let her idle for a good 20 minutes. Gave the solenoid a vacuum test. It definitely applies vacuum when you rev the truck up and hold it steady, I'll have to use my timing light to make sure it's the correct amount according to RPMs.

I grabbed the throttle and pulled it backwards, as in trying to close it. You could hear the idle die down. I think that's one problem right there, throttle is open a little wider than it should or TPS voltage is higher than it should be. My TPS passes voltage tests so I will play with the throttle plate stop screw and see what happens, and replace if I can't get it where I want it.

The truck's exhaust is HOT, which I was told indicates running lean, and it backfires softly and aside from a random delay in between, constantly. Excess air getting past the throttle could cause it to be running lean.

I also disconnected my brand new IAC while the truck was idling, and idle did NOT die down. That was the reason for replacing the first one and this one's doing it. I'll double check that it's getting voltage, but I think the throttle is the problem.

After all this I'll plug in the EGR and see if it dies haha.

 

Not trying to be a smart but here or anything, but i solved every problem my truck had about 2 weeks ago when i put a carb on. I will never get rid of this truck now. It runs good and it dont act funny now.

 

ROFL. Pick-N-Pull just put three 85 F150s on the lot. All three carb'd 300s.

That'll be my last resort haha.

 

Hey Pro,

How difficult was that to do? Not meaning to hijack your post Dready. Just have thought about this myself as I am a big carb fan myself and need a little guidance on how hard this would be to do. Money wise and time. Thanks.

Ohh Dready I am sure you would know, how do I tell if my blocked off egr is sending a closed signal to my computer? Thanks man. Ok hijacking is done. Sorry. Ill delete the post if you want me to and if you guys wanna post in my stalling thread or pm me that cool.

 

come on now, efi is easy... sometimes. Did you happen to clean the t-body recently? I've heard that over cleaning the t-body can actually cause too much air to pass. It kinda sounds like you have some sort of vac leak imo.

 

I seafoamed the truck when I got it on the road in March. And yea, I did clean it pretty thoroughly back then with throttle body cleaner as well. I had the throttle body off so I'd say I cleaned it REAL good.

Gonna back that screw off tomorrow morning if I wake up and drive the truck to work. I'll back it off till the TPS's closed throttle voltage is in spec, cause I know it's off right now.

It takes a pretty big vac leak to kill a truck as it's riding down the road at 45 MPH right? With no sign of imminent danger?

Michael, how is it blocked off? If the valve is still fully functional but just doesn't dump into the intake manifold then I'd think you'd need to plug the EGR solenoid and the valve nipple. That way when the solenoid tries to apply vacuum to the valve, it won't be able to. Valve will never move, EVP will never sense movement, will always report closed

 

it is blocked off with a plate and non existent.. lol. Just wanted to make sure it was that easy or not. Because it does have electrical connections that are just there doing nothing but hanging out. I just figured something had to be done with the electrical connections or something to make it send the right signal to the computer. I HATE EMISSIONS>>>>> ARRGGHHH.

 

Naw you should be fine then. I mean I don't mind some of the aspects of an EGR valve. It's supposed to decrease the combustion chamber temps (inert gasses don't burn so don't get any hotter than they already are). Lower temps means cooler valves means cooler running engine. A truck ain't environmentally friendly with or without EGR haha.

No connections means no signal to the computer period. Should set codes but that's about it.

My truck ain't running great right now but I drive it sometimes with EGR connected and sometimes disconnected and cannot tell a power difference, so yea, aside from more stuff that can fail it does serve an alright purpose.

 

FYI, heres how I blocked off my egr...