starting issue, 2.9L EFI

My 1990 BroncoII, 2.9L V6 EFI (same as Ranger) engine, has an issue with starting. It hardly ever starts the first time the key is turned. I've been following Sharon's thread with the '88 Grand
Marquis (in alt.autos.ford) and I read the 1990 F-150 starting problem from a while back in alt.trucks.ford.
The following two sequences of events consistently start the vehicle : turn key to on, hear fuel pump for a couple of seconds turn key to start, engine turns over but doesn't start turn key to off, turn key to on, again hear fuel pump turn key to start, engine starts
At this point, the engine will sometimes (probably half the time, or more) stall after having started. If I start it again it is fine. Alternatively, if I hit the gas pedal before it stalls then there is a delay while the engine "thinks" about stalling then revs up and is fine. The engine is fine all the while I am driving, even down the expressway at 60 or 65 mph.
Here are the tests I've done so far :
I always (well, when I've paid attention; I'm hearing impaired and its easy not to notice) hear the fuel pump run for a couple seconds when the key is turned to "on".
Turning the key back and forth between "On" and "Off" doesn't make a difference. The engine still needs to fail to start the first time before it will start. It's as if turning the key to start tells the system that I really do want to start the vehicle and then it gets ready the second time. (kind of like telling a kid to do something and the response only comes the second time)
Pushing the gas pedal first, like used to be required with a carburetor, is not consistent. Once when I tried it it started the first time. Other times it still required the two tries to start.
I located the Schrader valve next to the intake for testing fuel pressure. However, the gauge I borrowed was too big to thread on it. Instead I turned the key to on, heard the pump, and turned it back to off. Then I pressed the release in the valve momentarily and some fuel shot out. A good sign, although I don't know the actual pressure in the system.
I found the inertia switch and put a volt meter on it. It reads 12 volts when the key is turned to "on" (while the pump is running). It reads 12 volts while the engine is running. This seems to indicate that the relay is working properly.
I put injector cleaner in the gas tank yesterday when I bought gas. I don't know if this will make a difference (it hasn't yet, but that probably takes some time to work). I don't _think_ the injectors or the filter are bad because the engine has sufficient fuel while driving.
Other potentially relevant information :
The previous owner of the vehicle replaced the gas tank and sending unit. Presumably they are not worn out, and presumably the filter was replaced with them. The fuel gauge has been stuck on empty at least since the replacement. I believe the fuel tank is not identical to the original (it's larger).
The engine idles kind of rough. It doesn't threaten to stall (except just after starting while cold) but does oscillate between a higher (~900 or 1000 rpm) speed and a lower (~700-800 rpm) speed. Perhaps that is related? Maybe the fuel-air mixture isn't optimal (a sensor gone bad)? Distributor or TFI module? (the rough idle isn't so interesting in isolation, unless it is indicative of something fatal to come)
Now that I think about it, I guess I should check the spark plugs just to be sure. Would an engine still start even if one or two (out of six) spark plugs aren't functioning properly? That could be the cause of the rough idle.
I'd like to find and solve the starting issue, although in the meantime at least it is consistent and I can always start it.
What do you think?
-D
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======================It seams your throttle body and idle air control need a good cleaning. It is a very common problem on Fords. It is a good place to start anyway.
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I pulled the throttle body off and it looks ok. No serious buildup of stuff on it. (some "discoloration" but I guess that's normal)
I also found the IAC valve, I think. I'm pretty sure. The shop manual calls it "air bypass valve" and it looks like the picture on the computer at Advance Auto Parts. Now I'm trying to undo the screws holding the electrical portion to the mechanical portion. One of the clerks at Adv. Auto Parts said the valve gets stuck closed choking the engine. The vibrations of higher rpms jiggles it loose which is why the problem only occurs when starting. Sounds plausible to me :-). A replacement is $60 from them; unavailable on Autozone's web site. I'm hoping I can get this one apart and solve the problem with a simple cleaning. I'm afraid I'll strip the screw heads, though (one is already starting).
I think its time to buy a supply of penetrating oil and a shop light :-). Nearly all my work is done long after dark, outside. especially now that summer is over it gets dark by 5:00!
-D
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: My 1990 BroncoII, 2.9L V6 EFI (same as Ranger) engine, has an issue : with starting. It hardly ever starts the first time the key is : turned. I've been following Sharon's thread with the '88 Grand : Marquis (in alt.autos.ford) and I read the 1990 F-150 starting problem : from a while back in alt.trucks.ford. : : The following two sequences of events consistently start the vehicle : : turn key to on, hear fuel pump for a couple of seconds : turn key to start, engine turns over but doesn't start : turn key to off, : turn key to on, again hear fuel pump : turn key to start, engine starts
My nephew just had the exact same thing w/ his Ranger - turned out to be low fuel pressure and a replacement pump cleared it up.
Dave
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I'll keep that in mind, if the IAC cleaning doesn't solve the problem and if a gauge reports the fuel pressure is low. I hope I don't need a new fuel pump ($130!) especially since the previous owner told me he replaced the fuel tank and sending unit. (I guess "sending unit" and "fuel pump" are synonomous, not separate components)
Thanks for the tip!
-D
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