thank you that is where i tested for voltage and the readings where as i listed i check it maybe 10 times and i do have 5v to it just low readiing on other should i see a difference when unplugged this all started as i was headed to dirt pit it stumbled as if it was low onn fuel and then of course after i got loaded and back on highway it cutoff i had to get towed got back to shop and had trouble keeping it idle and my father put a map sensor on it he had at his shop and now it idles and you cant really get it to miss or stumble until you go for a ride then it seems to be out of fuel pressure test at 31 psi

 

The voltages I posted is with the TPS plugged in and the connector back probed.
31psi is normal for a V-8 at idle with good vacuum.
But the fuel pressure should go to around 40psi when you goose it to WOT for a V-8.
The fuel pressure should never go below 30psi or over 40psi while the engine is running.

 

good morning sir i went out this morning and tested fuel pressure and its 31 at idle but when i grab thorrtle and goose it from under the hood it has no change it sits at 31 or 30 i unpluggeg regulator and it climbed to 40 but no change when i gas it im going to go out to shop now test sensor again with the data you gave me to make sure readings i gave you where true thanks for your help

 

I acquired 2 TPS sensors, both used, for testing in relation to my existing unit. One Motorcraft, the other aftermarket.

I checked their resistance values & voltages loose & unmounted since the throttle shaft tangs bias the TPS readings because it has its own separate return spring.

They read out in order of voltage, closed & WOT, resistance closed & WOT:

MC, .470/4.62 & 3480/290 Ohms

Aftr Mkt, .340/4.80 & 6660/610 Ohms

When removed & tested loose my original Motorcraft TPS read out:

.980/4.85 & 3270 Ohms/260 Ohms.

I might have opened up the slots on my original TPS & gotten close on some values, but I decided to go ahead do that to the used Motorcraft part & see what happens. I mounted the TB in a vise & slotted both sets of mounting holes with a fine rat-tail file before mounting the TPS. I started by clocking the TPS so that WOT resistance gave me 350 Ohms & a resultant 3190 closed.

When hooked into the harness on the truck for a voltage check prior to bolting down the TB, I got .980 volts closed. I decided that might still be a bit high, so I loosened the screws & clocked the closed voltage back down to .950 volts which resulted in a 360 Ohms WOT/3200 closed resistance.

I buttoned everything up & gave it a test drive. It started easily & idled in its usual pattern. The shifting seemed to be more precise, particularly the 2-3 & the tendency to hunt for OD between 45-50mph was gone.

I did one 4-point turn around without a stall on the road & never got below 750 RPM while rocking the shifter reverse to drive. The drama of interstate exiting or coasting to a stop at an intersection was pretty much gone & the RPMs stayed fairly steady. Idle stayed at almost a constant 900.

I did have one reverse stall doing a second 4-point turnaround when I got back to my shop & was pulling it in.

I believe that I will start saving for a actual new Motorcraft IAC to see if I can eliminate that last bit.

 

Here is a way to get test points without piercing the wires on a TPS. First give the back of the plug a shot of WD40 to make pulling the green rubber seal with a small flat blade screw driver (jeweler size) easier. Then take regular straight pens & press them in next to the pin inside the plug. This keeps you from putting holes in the wires & having to reseal them with silicon.



Just press them in enough to hold. Not enough to crush the plug pins or dislodge them