89 F150 302 EFI

I don't really know how to describe this w/o giving an example so bear with me... I typically drive my truck to work, park it all day and then drive home late in the afternoon. The truck starts fine and makes it to work with no problem. After work, the truck starts fine and makes it home w/o any problem.

But lets say I get home and rest for 30 minutes, then go start it to run an errand. It hesitates to start, I might have to try two or three times, but it eventually fires up.

After that though - within 2 or 3 minutes - it stalls and will not restart. If I let it sit for 3-4 hours and then go back, it starts again and runs with no problem at all. That same pattern keeps repeating...

Start & run in normal cruising/operating mode.
Shut off.
Sit for a while. (10 minutes plus it seems like...)
Hesitant restart.
3-4 minutes of no problem, then stall.
No restart or run for 3-4 hours.

The only code I've gotten is a 31 which is an out of range EGR valve position sensor. I will test that sensor this weekend, but I don't see how it would be causing the problem. I've also disconnected the EGR valve vacuum line, but no dice - it still does the same thing.

Any ideas? Please help, this thing just keeps ruining my days...

 

Ignition module.

 

Sometimes a faulty gas cap will cause these kinds of weird problems.

 

By any chance does the amp light come on when it stalls? Normally followed by an inability to even crank the engine. If so, take it to Autozone and have them check the charging system (alternator) for free. That would at least eliminate that problem. Chances are, your EGR code could be caused by improper voltage to the sensor, because of the charging problem.

 

As in the whole EEC or just one component somewhere?

Could you give some more explanation? I don't quite understand what the gas cap would have to do with it...

Nope, no lights when it stalls other than the normal stuff that happens when the key is in the run position and the engine is off. Afterwards, when I try to restart it, it cranks just fine. The battery always has plenty of juice, and I've got a solid 12v everywhere I've checked...

Any other ideas?

A couple of other things, while it's in the process of stalling, it sputters like it's out of gas. There's plenty of fuel in the tank, so I know that I'm not running out. If I take my foot off the gas & coast, it will keep running, but as soon as I add throttle it starts to sputter again. If I stop & park, it seems to idle ok, but when I drive away the sputtering comes back and I eventually stall.

After it stalls and I try to restart, it smells 'flooded'. I know it's EFI and so it doesn't really 'flood' like a carb does, but I get a strong charcoal smell from underneath.

I've tried adding starting fluid to the air cleaner. Sometimes it'll catch and sputter for a minute, but again if I add any throttle it dies.

 

Have you ever replaced the fuel pump? Occasionally a fuel pump will give similar symptoms before it finally completely gives out.

 

Well, that doesn't sound quite so much like the ignition module, but it's still possible... That's the piece attached to the side of the distributor with the wires going into it. If you haven't already done so, you might replace the fuel filter and check the fuel pressure. Could be a pump. as samtpack says. Also, pull the vacuum line off the fuel pressure regulator to make sure no gas is getting into that vacuum line.

 

Thanks for the suggestions. I checked the EGR as well as I could. I got it off of the intake manifold, but couldn't get the bolt off of the exhaust line that connects underneath. From what I could tell though, it wasn't dirty or anything and the position sensor operated smoothly. I don't have a vacuum pump so i couldn't really test the response of the position sensor...

I will see if I can find a FP tester and vacuum pump to borrow. The cheapest ones I can find are $40, and I don't want to spend that kind of money on stuff that I'm going to use once and never after that...

I will post again if I figure anything else out...

 

my experence with ingnition moduals is they are picky, when mine was going out i could be driving down the road at a stedy speed and the engin would just quite. when i tried to restart it it would crank and get gas b/c i would smell it, but it wouldent fire.
what it sould like to me is the coolent temp sensor. your engine thinks that the coolent is like -150 degrees and gives it way to much gas causing the flooding and poor running and hard restarts. when my coolent temp sensor went bad, i sometimes had to hold the gas petal to the floor to shut the injecters off or it wouldent start. if that isnet the problem then i would try o2 sensor, intake air temp sensor, or tps
-hope this helps, vochy

 

also if the coolent temp sensor is bad you might get noticeale bad gas milage between 9-11 miles per gallon

 

Vochy... that's one of the things that I suspected.. If the EEC thinks that the motor is cooler than it is, then it will mix too richly and won't burn... On the other side, if the EEC thinks that the motor is hotter than it actually is, it will lean out the mixture...

And yes, I do get crummy mileage... I'm going to look at the fuel pressure regulator today, but the coolant temp sensor may be next on my list...

Is there any way to test the CTS?

 

My book sez 58.75 K ohms at 50 deg., 37.3 K ohms at 68 deg., down to 2.07 K ohms at 212 deg.

 

c96, I found a chart for it at fordfuelinjection.com (GREAT site, by the way) but the problem is heating it up to a known temperature...

<<<scratches head...>>>

The only thing I can think of is boiling some water on the stove with a kitchen thermometer in there, then checking it every 10-20 degrees as the temperature falls off...

I also want to install an electronic fuel pressure gauge that I can mount in my cab. That way, I can check to see what my fuel pressure is doing when it starts to sputter. The problem is that the only electronic fuel pressure gauges out there come as part of a kit. Those kits (Autometer, Greddy) run well over $150 - that's waaaaay too much to spend on troubleshooting...

All I really need to do is get a sender and run wires into the cab where I can have my multi-meter connected. I don't really care what the exact pressure is, I'm just looking for a big drop when it stalls. Is there any reason I couldn't buy a cheapo oil pressure sender and use it for this?

 

I'm way late in the conversation here, but maybe this will help others. If you have dual tanks, check the fuel tank selector valve (located in between the gas tanks and the mechanical fuel pump on the left side frame rail).

I've had similar problems: starts fine, runs great, but all of a sudden for no reason, my '95 F250 (5.8L EFI) would stall or fail to restart.

I uncovered the problem by switching the fuel tank switch -- on the dash -- back and forth a few times. Replacing the fuel tank valve ultimately solved the problem.

See chapter 4-11 of Haynes or the chapter about the fuel system in Chilton's.

Hope this helps.

 

Changed your fuel filter lately? Does it turn over with full juice or sound like the battery is weak?