Hey all! I am new to the forum and thought I would start off by saying "hello" and talk about some of the issues I am having with my father’s truck.

It is a 1990 F150 with a 351w.

Issues (from an email my father sent me):

1) When I run the truck through the car wash, sometimes while in the car wash the engine will suddenly race up to 2,000 rpm and occasionally the check engine light will come on for a while. When this happens and I am in the car wash, I shut the engine down and wait for the car wash to finish then start it up to leave and it is fine and not racing to 2,000 rpm. So, this is strange as something is getting wet and shorting something out?

2) Another thing, and it may be related to item 1 above, is that I seem to “eat” MAP sensors and ICM’s. I seem to have to replace the MAP sensor every couple of months and every 4 or 5 months I have to replace the ICM.

I get massive engine vibration and no power before I replace the MAP sensor. I swap out the MAP and it goes away but the truck still has been running rough for a long time now. The ICM goes out every now and then and the acts like it is running on 4 cylinders so I always carry a spare (it has only happen twice in the past year and half).

3) Main issue: Truck idles rough and the gas smells coming out of the exhaust. Here is what I have done and/or replaced:

· Plugs look great but I replaced them anyway.
· ICM
· TPS
· MAP
· IAC
· EGR Solenoid and Valve
· Coil (from one I had leftover)
· Ignition wires
· Rotor and cap
· Distributor
· Fuel Filter
· Checked timing at 10 degrees BTC (I also trying playing with the timing by setting it at 13 BTC, 8 BTC, etc but it made not much of a difference other than a change in power so I moved it back to 10 degrees).

When I go full throttle the truck takes off.


My father is handing the truck off to me to take a turn. If anyone has any input on where to start or had a similar issue, please let me know. I am deploying soon and would love to have his truck running strong so I don't have to worry about him.


Thanks!


Stang

 

If you're eating MAP sensors, I would suspect a possible problem with the computer's voltage supply.

Measure the supply voltage at the MAP sensor. It should be no more than 5.00 volts.

 

For the racing at the car wash I would unplug the EEC Computer plug and apply new dielectric grease to the plug.

As noted above yo may have a power supply problem with the EEC Computer and it may have bad electrolytic capacitor inside. So I would also open it up and check the electrolytic capacitors.

I have heard that a bad alternator can cause strange problems also.