We own a 1989 F150 v8 with 150000 miles. We know that the previous owner never did an oil change or tune up in the 2 years he owned it, before that we have no idea. Here in the last 2 weeks it has really started running rough. It has started to miss and the fuel smell is horrendous! It has to be running too rich. We have changed the spark plugs, wires, cap and rotor, fuel filter and air filter. We have given it a full oil change. We also checked the vacuum hoses. The more we fix, the worse it seems to run. As of yesterday it started to stall and shake tremendously at take off, and if you are taking off from stop or sitting in idle revving the engine, the check engine light comes on, flashes three times, and then goes off. We are at a loss as to what to check next. Anyone have any ideas?

 

Timing chain. Put it on #1 TDC and see where its aiming on the distributor. if it aint pretty much dead on #1 your chain is bad.

 

We messed with the timing a little bit...having it checked by a mechanic friend today. Would that cause the heavy fuel fumes too?

 

Take it in for a code check first

 

I believe if you look on the firewall at about the heater/a/c location you'll find a box with a rubber hose to it. As the truck runs, disconnect the small hose. If the idle doesn't change the MAP sensor is bad or there is a leak in the hose. If you put your finger over the hose, the idle should pick up if the sensor is bad. It's also a common fault that causes the engine to run rich....real rich. If you intend to keep the truck, an OBD1 scanner would be a useful tool. It'll keep you from replacing good parts.

 

Okay, so we tried the test for the MAP sensor and the truck just died. Took it in to have the codes read and they said it was too old to check.

It just keeps running worse and worse.

 

too old to check? its got an obd1 connector under the hood on the driver side fender. http://www.amazon.com/s/ref=nb_ss_gw...d1+code+reader you need one of the ford obd1 code readers in the link i just gave you, or you could get one off ebay.
make sure all the plug wires are pressed onto the plugs good.

 

The fuel pressure regulators were good for sticking and causing excessive fuel pressure. Actually had a recall for them. You need to check the fuel pressure. Try unplugging the electrical wire from the MAP, not the vacuum hose, then see if it runs any better. I have done that when they were bad to buy some time. The CEL will come on when you do. Also, if it is a V8, the gasket between the upper and lower intake will fail causing a vacuum leak. Spray carb cleaner around the area and see if the idle changes. There are a bunch of things to check on that truck. But first, cover the basics. Fuel pressure, vacuum leaks, base timing, crossed plug wires are just a few.

 

Thanks, we'll get a an OBD1 sensor and try the other options. Matt is about to just give up and buy a new vehicle...

 

Take the Vac line off of the EGR. If the engine runs good then the EGR is bad, Or the cheaper fix, The vacuum control valve. Located in the middle of the block at the rear. You can follow the vac line around the rear of the motor to the controller. To test the vac control take the elect plug off of it, Start it up, If you still have vacuum at the EGR line, The vacuum control is bad. It sells for around $40.00.

 

this thread was done in march. and if the engine runs good after disconnecting the egr vac line then the egr is perfectly fine, the problem would be the evr or pcm.

 

He has posted the same exact thing in 3 other old posts that i have came across.

 

i know, he made another post to one in the pre97 forum but i didnt bother replying to that one.

 

3? Try about 7.