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Discussion Starter #1
So, I've searched around and come up with some ideas, but I wanted some more input. My truck had been sitting for a week or two and was hard to start when I took it out the other day (Very unusual, It usually cranks right over even after sitting) Then, when taking off from a red light it started sputtering and almost shut off. Also, sometimes it will hesitate and kinda sputter at low rpms around 35mph when you give it some more throttle. I'm thinking its a fuel issue, but I don't want to start replacing things without diagnosing the issue. Any thoughts on where to start looking?
 

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Check fuel pressure. Also on the fuel pressure regulator is a vacuum hose. Pull that off and smell it. If you smell gas it's bad. Take off and clean your iAC as well

most importantly pull codes
 

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What size motor? Transmission?
 

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I agree, first "pull codes" from the computer and see what faults are indicated for initial diagnosis, www.fordfuelinjection.com....then pressure guage test the FPR = fuel pressure regulator for PSI which should be 37 psi engine off cranking, 40 psi engine running.....FPR's run about $23.00 each...

Next pull off the IAC = idle air control and clean the valve bottom part only with TB cleaner and replace the gasket if need then move on and test the TPS = throttle position sensor for voltage setting using a multimeter, ideally .93-.97 volts or less then 1 volt.
Keep in mind the most TPS sold today are a "plug & play style meaning a slight CCW then CW turn in hand placed on the throttle body shaft end engaging the "tangs" in the center spring loaded ring then tighten mounting screws insures proper function otherwise it's like being in neutral and inaffective.

There's a Ford Racing Performance Parts idle setting Instruction Sheet, steps 1-9 either on wwww.broncolinks.com, here on FSB or Techline (800) FORD788 which explains how to drill out holes for a p&p TPS for actual adjustment and how to adjust idle using the throttle body idle stop screw, the IAC disconnected matching RPMS on the dash tach...very simple procedure.

I would test the ignition module either the direct distributor mounted TFI = thick film integrated or remote mounted style module but test it several times for a passing grade and replace with a Motorcraft.

Last, another possibility with the distributor could be with the PIP = profile ignition pickup which is an ignition signal/sensor on the end of the dissy shaft where you'd need to pull out the dissy and test but not expensive to replace by itself.

Good Luck ~ :thumbup
 

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JK, fuel pressure running will not be 40psi unless the vacuum hose is removed from the pressure regulator.
 

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OK for future reference what is the PSI supposed to be if the FPR line is not disconnected with the engine running.....?


Good Luck ~ :thumbup


Anyone know what it is, please post so we all know either way ~ Thanks :rockon
 

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Discussion Starter #8
Thanks guys, I was leaning towards the fuel pressure regulator.. I'll get into it more this week and post back with my findings.
 

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Discussion Starter #9
It was the fuel regulator, replaced it, and it's running great. Thanks for the help!
 

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Discussion Starter #10
Update, after replacing the regulator (which was bad, based on the sniff check of the vacuum line) the next day it was hard to start again. I pulled codes and got a CM code 51 for the ECT, replaced it, and the next day again it was hard to start. The issue is only starting it cold after it's sat over night. I cleaned the IAC today, but like I said, I really won't know if it did any good till I start it up after it's sat. Help! :cry:scratchhe:madder
 

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Is your distributer cap, and rotor caked with white residue along the metal contact points? If so, clean it off with emery cloth, and see if that helps. If so, replace them soon, because I don't know how long you can get away with scraping the metal away. That is off the top of my head.
 

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You may also have **** caked up around your butterfly valve on your throttle body keeping air from bypassing the opening. Throttle body spray, and a rag will work on that. Do not spray into the throttle body though. I destroyed my tps on another vehicle doing that. Just dampen the rag in it, and wipe all around the opening.
 

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Discussion Starter #13
I'll check it out, but I did a tune up only a few months ago, so I doubt it... wouldn't that cause poor running in general?

Is your distributer cap, and rotor caked with white residue along the metal contact points? If so, clean it off with emery cloth, and see if that helps. If so, replace them soon, because I don't know how long you can get away with scraping the metal away. That is off the top of my head.
 

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Discussion Starter #14
That's easy enough to check and worth a shot. Didn't look too gunked up when I had the intake tubes off earlier. Can't hurt to clean it anyway though. It just has me stumped because it's only hard to start cold.. and it sputters a bit under low RPMs around 30-35mph..

You may also have **** caked up around your butterfly valve on your throttle body keeping air from bypassing the opening. Throttle body spray, and a rag will work on that. Do not spray into the throttle body though. I destroyed my tps on another vehicle doing that. Just dampen the rag in it, and wipe all around the opening.
 

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Last, another possibility with the distributor could be with the PIP = profile ignition pickup which is an ignition signal/sensor on the end of the dissy shaft where you'd need to pull out the dissy and test but not expensive to replace by itself.

Good Luck
I found a cool trick for testing the PIP when the motor will crank but not start, using a cheap LED light from Radio shack (part #276-0270), without pulling the distributor.



You connect the black lead to the #6 wire at the TFI (ICM) 6 wire connector, and the red lead to the positive battery terminal. Crank the motor. If the LED blinks on and off, then your PIP is sending signal to the TFI... if it doesn't blink on and off you have a bad PIP.



 

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Discussion Starter #16
Ok, I'm really getting pi$$ed off now.. (Though I thank all of you for your help!)... Today I tested the IAC and got what I thought was a bad reading and replaced it. It started fine, but it still had that sputtering or almost what feels like a missfire or shudder at mid throttle after it shifts into 2nd gear. Now, when I just drove it to the firehouse, it started right up no problem but then stalled upon putting it in drive and giving it light throttle. Started right back up after that, and then lost power (sputtered) as I pulled out of the driveway. The rest of the ride was fine, aside from that missfire feeling in 2nd gear. I have to get this truck running for the winter, I suppose my next step is checking the fuel pressure. The fuel filter and regulator are new. Could that PIP cause these issues? I figure that's just for a motor that will crank but not start. Anyone with any advise would be greatly appreciated. I'm near ready to take it to my mechanic, which I really don't want to do because I can fix just about anything on the truck myself, I just can't seem to diagnose this issue.
 

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I'd guess the PIP is working because you have spark.... sounds more like a misfire or TPS thing, but I could VERY much be wrong. I'm not sure if the PIP is a work or don't work type of thing... but according to the Ford Fuel Injection Website (www.fordfuelinjection.com), "without it working properly the computer never senses the engine moving and the entire vehicle is a paper weight." Have you tested the TPS? You can also put a spark tester on each spark plug wire (one at a time) and test for misfires. If you're not getting a spark everywhere, change the Cap, Rotor, and check resistance on all your spark plug wires... or change those, too.

Mine had a high random idle at times when stopped at a light, or in drive, and some strange stumbles out of nowhere while driving. It ended up being the connector to my TPS... which I found when going to test it. A quick cleaning of my connector and I was good to go. http://fordfuelinjection.com/index.php?p=30 has instructions for testing the TPS.

I hear your frustrations... last week I went about crazy figuring out why mine wouldn't start. But keep with it and you'll figure it out. Keep pulling codes just in case! But testing spark on all cylinders, testing the TPS, etc.... could find what's wrong. Keep updating!
 

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Discussion Starter #18
Thanks for the support.. I tested the tps, its fine. It drives fine with a heavy foot too. Tomorrow I'll thoroughly check for vacuum leaks. Is there any way of checking for spark in my back yard, or how much is a spark tester?

I'd guess the PIP is working because you have spark.... sounds more like a misfire or TPS thing, but I could VERY much be wrong. I'm not sure if the PIP is a work or don't work type of thing... but according to the Ford Fuel Injection Website (www.fordfuelinjection.com), "without it working properly the computer never senses the engine moving and the entire vehicle is a paper weight." Have you tested the TPS? You can also put a spark tester on each spark plug wire (one at a time) and test for misfires. If you're not getting a spark everywhere, change the Cap, Rotor, and check resistance on all your spark plug wires... or change those, too.

Mine had a high random idle at times when stopped at a light, or in drive, and some strange stumbles out of nowhere while driving. It ended up being the connector to my TPS... which I found when going to test it. A quick cleaning of my connector and I was good to go. http://fordfuelinjection.com/index.php?p=30 has instructions for testing the TPS.

I hear your frustrations... last week I went about crazy figuring out why mine wouldn't start. But keep with it and you'll figure it out. Keep pulling codes just in case! But testing spark on all cylinders, testing the TPS, etc.... could find what's wrong. Keep updating!
 

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Thanks for the support.. I tested the tps, its fine. It drives fine with a heavy foot too. Tomorrow I'll thoroughly check for vacuum leaks. Is there any way of checking for spark in my back yard, or how much is a spark tester?
I have this one... It was like $5 at Autozone. I like it because it will check spark strength too with an adjustable gap.

 

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Discussion Starter #20
All I had time to do today was check the timing, which is dead on... I was also looking at the EEC and FP relays, as I was reading some threads where a failing EEC relay was causing pretty much the exact same symptoms as I have. Both my relays have some corrosion around where the wires go in the female plugs. Also, I realized I haven't been paying too much attention to listening to the fuel pump priming, as it did it the first few times I checked for it... but, today when checking the timing the fuel pump didn't kick on, then when I tried keying it to "ON" again it took a few seconds, then primed. I think I'm onto something with these relays, they would explain the spiratic symptoms.
 
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