I have a '93 F150 4x4 with a 5.0 and 4spd. It has developed an off idle bog, like when you are accelerating from a stop sign. Could this possibly be the MAP or the TPS, if so which one? There aren't any check engine codes showing and the truck runs fine otherwise with the exception of running a bit too warm(in my opinion).It is getting near 20 mpg (cdn) as well. Any thoughts on this?

 

Your problem has all the trademark signs of a low TPS voltage. This is where I would start. Verify your voltage and repost- we'll go from there. RSH

 

Don't mean to ask a dumb question but, here I go.
What does TPS stand for????? Reason I ask is I
have an 1987 F250-4V that falls on its face off
the line. I don't know if the problems are related
because I have a carb. Sometimes it runs great and
sometimes it doesn't, thats what puzzles me. When it's
running bad you can smell fuel. Like it's getting to
much. There is a valve on my inner fender well that
melted I guess because air pump locked up. No cat,
air injection manifolds.A friend told me to disconnect
all off that stuff but I don't think that is a good
idea.Sorry so long, just trying to be detailed.
Thanks in advance, Dan

 

I'm not positive on this, so someone please correct me on this.

TPS stands for throttle position sensor. As the name implies, it tells the computer how hard you're hitting the gas pedal. Before fuel injection, there was a cable running from the pedal to the carb, so a carbed engine won't have a TPS.

In other words, you're looking at two completely different problems.

 

dk your problem with your four barrel is most likely caused by the "discharge nozzle" (commonly known as a "squirter") that works in conjunction with the accelerator pump and the plastic accelerator pump cam. The discharge nozzles can be obtained in different sizes ranging from .025-.052 . If this was an aftermarket universal carb they are generally on the "fat" side (rich) since they may be used on a vatiety of engines. In short the accelerator pump determines the maximum volume of fuel discharge and the nozzles determine how long the shot will last. The plastic cam determines the amount of fuel delivered by each stroke of the pump. As a rule of thumb use the smallest squirter and cam that prevents hesitation. Excessive pump output will degrade throttle responce/ bog and is basically a waste of fuel. Don't mean to be long winded or confuse you and keep in mind this is for Holley carbs. Hope this helps. If you need any help let me know as I am quite intimate with the Holley. Regards.

 

>Your problem has all the trademark signs of a low TPS
>voltage. This is where I would start. Verify your voltage
>and repost- we'll go from there. RSH


How do you verify voltage?Do you just kinda plug in right at the sensor connection or what?What is the voltage range supposed to be?Later,

Cleve

 

Using volts dc on your multimeter the positive lead should pierce the green or middle wire on the actual tps and the negative lead to the black wire. The idea is to get as close to 1.00 volts as possible with out actually reading 1.00 or going over. I set mine to about .997 vdc and it made a noticable difference since my voltage was way off. Depending on the way you "pierced" the wires I just used electrical tape to cover the area for peace of mind. RSH