Ok here is my problem. I have 1991 F150, 302, 4x4, 5 speed mazda. The truck barely wants to idle, very shaky and rough, when in gear it only goes about 5 mph and its a very sketchy 5mph. I also get some smoke coming out of the exhaust.

Now this problem just popped up the other day. I let the truck sit a day and it went away. Ran great for about a week or two and now its back. I checked all the plugs and wires and they all look great.

So, I have no clue what it is. I pulled the codes and all I get is a 72 and a 41, MAP sensor and temp sensor. I checked the temp sensor and it checks out good (engine was cold when I did the test). As for the map sensor I get 5 volts on the ref. but only 2.59 on the signal. I don't have a tack meter to check the frequency.

So any help is greatly appreciated!!!

 

You can check fuel pressures. And also, could it be moisture on the plug wires interfering, if the wires are old, i'd try that. Or you can give em the water test, with the engine on just spray some water on the wire and see if it does anything.


Primary rig is:
95' F-150 XLT 4x4, 302, 5 spd, MSD 6A, Sunroof, and some 32" BFG Muds .

Pictures are in!!


Then theres:
99' Mustang GT 4.6L
88' F-250 Superduty 4x4 351/c6
95' Mercury Cougar 4.6L V-8
80' E-350 300/6 with a
3 spd column shifter. Top speed is 65mph, Go Baby Go!

 

Well here is where I stand now. I have replaced all the plug wires, cap, rotor, and plugs. I checked the coil and that test out ok. I also check the power going into the tfi module and that ok also.It will run but very bad. I sprayed water on the headers and the number 1,4,5,8 cylinders it turns to steam, but on the inside two cylinders (2,3,6,7) the pipe stays wet.

If I pull a plug it is soaked. The spark also looks alittle weak on that cylinder. So I am thinking, somthing to do with the injector?? Distributor (I tried a spare and the samething)?? or ???

PLEASE HELP! I am going insane here

 

Hey help,
I'm assuming that the plug is 'wet' with fuel? That would mean that it's not firing and all the fuel is buiding up. Not being familiar with your car I would do a quick spark test to make sure you're getting spark. Pull the plug off of the plug that is 'wet' and have someone start it up and see if there is a spark arcing to the chassis. Check that out. Do one at a time to see if you actually have spark to all of them. You could have a bad timing module. Take note that it's a strong arc. A weak arc can be as bad as no spark since this spark is what ignites the pressurized fuel.

Dan