1995 5.8L starting issues
Lead Driver
Joined: Aug 2006
Posts: 5,670
Likes: 13
From: Sand Lake, MI
i have blanked off the iacv and the truck idles normal. but only after i get it started with either. just unpluging does nothing which is why i stated something is telling the iacv to open too far and restrict fuel. not enough fuel on start up but once i get it started with either it will run normal with the iacv blocked off and without blocking it off it idles at two grand.
Ok with the key off unplug the IAC connector, test the wht-lt blu wire in the connector for continuity to ground.
If find it has continuity to ground unplug the harness connector from the PCM and retest.
Lead Driver
Joined: Aug 2006
Posts: 5,670
Likes: 13
From: Sand Lake, MI
Its in the firewall slide into a pocket down low under the master cylinder, stands vertical and is connector nearest the fender. The harness connector is only part of it proud of the surface of the firewall.
One 10mm bolt in the center holds the connector in place.
Post #13 by Subford shows location.
https://www.ford-trucks.com/forums/9...-problems.html
One 10mm bolt in the center holds the connector in place.
Post #13 by Subford shows location.
https://www.ford-trucks.com/forums/9...-problems.html
Lead Driver
Joined: Aug 2006
Posts: 5,670
Likes: 13
From: Sand Lake, MI
Yea I believe its the same (and someone please correct me if I'm wrong), only difference would be if actually removing the PCM from the truck.
Later models pulled out from the engine side of firewall, earlier models removed from under dash? Other then that same location for the harness connector.
Later models pulled out from the engine side of firewall, earlier models removed from under dash? Other then that same location for the harness connector.
Cargo Master
Joined: Jan 2004
Posts: 3,118
Likes: 149
From: South Dakota
My advice try the TPS or get a Haynes manual and a multi-meter. The Haynes manual tells how to test most of the sensors.
Lead Driver
Joined: Aug 2006
Posts: 5,670
Likes: 13
From: Sand Lake, MI
Definitely worth the few minutes it'd take to check it out, verify its either right or out of range.
Test/values for TPS,
Fuel Injection Technical Library » Throttle Position Sensor (TPS)
Test/values for TPS,
Fuel Injection Technical Library » Throttle Position Sensor (TPS)
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Fleet Owner
Joined: Oct 2005
Posts: 20,786
Likes: 1,751
From: Kentucky
Another thing to look at related to the starting issue is the MAP sensor. I have seen several cases where the MAP was passing the KOEO/KOER tests but the output signal was not correct. Before tossing on a new one run the KOEO tests and check for stored codes (CM).
You can also test the MAP sensor with a meter that also measures frequency and a vacuum pump. Use this for reference: Fuel Injection Technical Library » Manifold Absolute Pressure Sensor (MAP)
You can also test the MAP sensor with a meter that also measures frequency and a vacuum pump. Use this for reference: Fuel Injection Technical Library » Manifold Absolute Pressure Sensor (MAP)
Thread Starter
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New User
Joined: Jan 2012
Posts: 10
Likes: 0
i have vacum gauge pressure is normal and steady. also have fuel gauge and pressure is correct. almost certain its electrical something not telling the injectors to supply fuel at start up. even with the iac unplugged and closed or blanked off, i still have to use either/ carb clean to get the truck to start. but once it starts it stays running. time to check wires. very frustrating you know for an ex aviation electronics expert i still hate this stuff. makes me remember why i got out the navy.
Fleet Owner
Joined: Oct 2005
Posts: 20,786
Likes: 1,751
From: Kentucky
i have vacum gauge pressure is normal and steady. also have fuel gauge and pressure is correct. almost certain its electrical something not telling the injectors to supply fuel at start up. even with the iac unplugged and closed or blanked off, i still have to use either/ carb clean to get the truck to start. but once it starts it stays running. time to check wires. very frustrating you know for an ex aviation electronics expert i still hate this stuff. makes me remember why i got out the navy.
Do not let the Ford EFI system get you down. You just have to learn how it works. It's really pretty basic. I work on medical imaging equipment for a living, it keeps my skills honed but really once you learn some of the basics of Ford EFI it starts to makes sense pretty quickly.
Cargo Master
Joined: Jan 2004
Posts: 3,118
Likes: 149
From: South Dakota
I will add to what I said under No. 22. I also had a bunch of weird issues in addition to the fast idle. There were days I would try to start it and it wouldn't start. Try it another day and it would start. Let it sit and warm up to normal operating temperature, shut it off and it would only restart if i held the gas pedal to the floor. Drive it down the road and it wouldn't shift right. Bottom line replacing the TPS solved all these issues as well as the fast idle.
What I'm trying to say is try to fix the fast idle problem and it will likely solve your starting problem as well. Yes, I think it's a sensor.
What I'm trying to say is try to fix the fast idle problem and it will likely solve your starting problem as well. Yes, I think it's a sensor.
Fleet Owner
Joined: Oct 2005
Posts: 20,786
Likes: 1,751
From: Kentucky
Yes, it will start with the MAP unplugged. I have seen it cause the no start issue several times on this forum.
Cargo Master
Joined: Jan 2004
Posts: 3,118
Likes: 149
From: South Dakota
When I was trying to troubleshoot mine I unplugged the MAP sensor. It slowed the engine way down and I was getting black smoke out of the tailpipe(excess fuel condition). I had no trouble starting it with the MAP sensor unplugged.