I have a 1985 F150 4x4 V8 5.0L FI that has a rather rough idle and "lopes" or idles unevenly. While idling the truck with "lope" and occasionally get close to stalling out and then come back to a rough idle. Other times the engine will actually stall out. Sometimes when driving the truck but sitting at a light in neutral or with the clutch depressed the truck will also stall out. Is this a case of needing to set the idle speed or needing to adjust the timing? I read the Hanes manual I have but not being a mechanic a lot of it sounds like greek. Any advice?

 

Welcome to FTE.

Your idle speed & ignition timing are controlled by the computer, I suggest asking the computer what it thinks is going on.

Here's how:

Ford Fuel Injection » How To Run a Self-Test
Ford Ranger/Bronco II EEC-IV Testing



But also make sure you don't have any vacuum leaks, the filters are clean, the ignition components are good, all the usual stuff.

 

Yes, check for codes. You should get at least one code when you check it. Also, when was the last time it had a tune-up?

 

Well the tune up has been at least 2.5 years since I bought it and the only thing I did then was new wires and plugs. I am going to get some new plugs and wires but should I invest in a new rotor cap as well? Ignition coil or condenser? I am not sure how to check for vacuum leaks. Could someone please advise? I know enough about cars for routine maint. but have never had to do that. I don't have the tool to check the EEC ignition control module. Is it something I can purchase or have done at Advance Auto or Napa Auto or something?

 

You do not need a expensive or complicated tool to run the self-test. All you need is a meter or a testlight. Just read the link he gave you above.

Yes, replace the rotor and the cap. No need to replace the coil unless it's corroded or damaged/leaking oil.

 

Got me a new rotor cap, wires and plugs. No change. Did the test as per instructed and got code 31 I think. Checked the EGR valve and it wasn't working and the EGR line was crimped. Will install a new EGR line, valve and position sensor. Also Checked the Idle air control vavle . . . looked ok but I got a great deal on a new one and will install that. I also wanted to change the fuel filter while I am at it but wanted some advice about that. I could only find the below object which I believe is the filter. How do I get to the filter? The liquid on the frame in the picture is Deep Creep that I put on some bolts to loosen them up.

 

I don't think that's the main filter, though I believe there is also a filter inside that piece(is that the reservoir? which is actually the tank switcher). Here's a picture.

AutoZone.com Repair Guide Image.

 

That diagram helped a lot thank you. I believe you are right. Ahead of that part I found the part pictured below. The diagram you posted seems to indicate that it would be the fuel pump assembly and bracket. What I could not find was the in line fuel filter. After the pump the fuel lines went up into the engine and on my truck the fuel pump and assembly is where the diagram says the filter should be. Can anyone suggest where I might find the fuel filter?

 

The filter on my 87 is AFTER the fuel pump. Keep in mind there are 2 pumps on your truck, 1 low pressure in each tank and the high pressure pump you have pictured. The filter should be after the high pressure pump right where the frame rail bends upward after the front cab mount.

 

Thank you for the help. The pump that is pictured is actually located on the inside on the drivers side frame just at the point you describe, The best I can figure is that post pump the fuel lines go up into the engine of the truck. I will double check. Is there another location that the filter would be located?

 

Not that I was ever aware of, however that canister may have a strainerin it. IIRC the bottom should screw off with a filter wrench.

 

Give us an update on your new Idle Air Control Valve install. That would of been my first guess from the description in your first post, so I wanted to see if that fixed your idle issue.

 

The black canister (properly called the fuel reservoir) indeed has a paper pleated fuel filter in it, one that is overlooked often and has caused many much grief over the years. It needs to be changed. Be careful, it is NLA now.

As mentioned, this is a much overlooked filter on the early EFI Fords (as well as many not even knowing about the mid year 85 302 EFI engine availability).

There should be another main filter by the high pressure fuel pump on the drivers side frame rail. This is the one that everyone changes

David

 

Ok. The fuel filter does not exist in the location that is mention or shown in the diagram below. Would it be located in the piece marked reservoir as suggested above. I have the part on order from RockAuto Auto Parts and when it gets here I shall let you all know. The EGR valve and position sensor have been lost by Fedex so I will have to get new ones.

 

David,

The there is no fuel filter after the high pressure fuel pump. In the diagram that is shown (found thanks to another poster) the fuel pump is in the location of the fuel filter and the only other thing before that is the reservoir. How do I access this filter? Someone mentioned a filter wrench. Will the round plastic piece on the bottom screw off similar to an oil filter. Also what do you mean by NLA?