I have a 1986 F-150 302 EFI. I recently got the truck and have been ironing out a few gremlins. I've got it mostly sorted out except for one problem. The truck starts, runs and drives perfectly for the first 20 minutes. Then, once it's warmed up, it will start losing power. Here's the scenario: Driving down the road at around 45mph, the power just cuts out (the RPM goes down the the idle range). Initially, I thought this was the transmission slipping, but I think the RPM's would rev high if the gas pedal was pressed during one of these "power loses". However, even if you put your foot to the floor, the RPM stays low. The engine does not cut out completely, it just loses power. Once you take your foot off the gas for a few seconds, you can reapply the gas and you will regain power (but only for a few more seconds, and then the problem repeats itself).

So, after doing some research in the Haynes manual, as well as the 1986 Ford Truck Shop Manual, it seems I might have a Emissions problem. I just get a little confused with all the abbreviations for the different valves and systems so I'm not confident to start troubleshooting yet.

There is one thing that very obviously wrong just from a quick visual inspection. There is a metal tube that runs from the back of the belt-driven Thermactor all the way down to the exhaust system. Well, the end of that tube is no longer connected to the exhaust. It appears someone has disconnected it and pinched closed. I don't know enough about this system to know if this is my problem.

I might be completely off base. I just don't know.

Any help would be appreciated. Thanks in advance!

 

try re-connecting that tube and see what happenes...if all else fails reconnect anything the was/is dis-connected!!!

 

I'll give that a try. I spoke with a guy from Advance Auto and he mentioned that the Thermactor or "smog pump" should not cause the problem I'm having. In fact, he said he removed it completely from his '86 Mustang and it ran great. He thought I might be haveing an EGR problem. Once again, I'm not too savvy on how that system works, but I might try replacing it and see how it goes.

 

There are three components to the EGR system, any of which could cause it to not work properly. You have the EGR control solenoid, the EGR position sensor, and the EGR valve itself. You should try pulling codes by running a Key On Engine Off (KEOE) and Key On Engine Running (KOER) test. That will save you a lot of money on un-needed parts.

 

RI-Truck,

Thanks for your response. As a matter of fact I just spoke with the Advance guy again and he recommended I do the same thing. However, I can't figure out how to do it. I either don't have a "check engine" light, or it's burned out. I do have a digital mulitmeter though. I hooked it up as closely as I could to to the Haynes manual recommendations, but when I try the KOEO test, the numbers jump around erratically and its undecipherable to me. I either have it hooked up wrong, or I just don't know what to look for.

I've attached a few photos to show how I've got it hooked up. Could you please "sanity check" it for me?





https://mail.google.com/mail/?ui=2&i....1&disp=thd&zw

Hope these photos work!

 

The 3rd photo works, you just have to click on the link.

 

If you are planning on keeping the truck a while this is one of the best investment you can make...I like this particular one because of the digital readout.

FORD CODE READER TOOL SCANNER DIAGNOSTIC SCAN OBD CAN : eBay Motors (item 230410548206 end time Feb-07-10 19:27:36 PST)

I can't see your pictures, but here's some info on pulling codes without a reader.

Ford Fuel Injection How To Run a Self-Test

 

Update: I figured out the code test. Turns out I didn't have the multimeter hooked up correctly. Both the engine-off and engine-on tests came back with code 11 (test passed). I guess the next step would be to remove the EGR valve to see if its clogged up with deposits. If so, I imagine I'll have to replace it. They look a little pricy...around $100, so I guess I'll be replacing the 3 separate parts one at at time.

Anyone have any other troubleshooting steps? Am I even going down the right "rabbit hole" given my original problem?

Thanks again.

 

RI_truck,

Thank for the links. I used the same directions to figure out the code testing. (my problem was I had the meter on the Volt side instead of the Continuity side).

I plan to keep this truck for a long time so I will certainly purchase the code tester you recommended. Thanks again!

 

Pulling and cleaning the EGR is a good next step. While you have the EGR off apply vacuum to it and check for movement. But I wouldn't buy any parts yet. There are more things that can be checked. First give everything a good visual inspection for anything obvious. Next for me would be giving the throttle body and plenum a good cleaning.

 

I'll do that. Once I get the EGR, Throttle Body and Plenum off, what should I use to clean them? Carb cleaner or something like that?

 

Carb cleaner is too harsh for fuel injector components and sensors. Most parts stores have fuel injection cleaning products. Some guys on here have said they get good results with Seafoam products, but I can't personnally recommend it. I've used the Lucas fuel treatment with good results.

 

I didn't pick up earlier that you're in VA Beach. PM me before you buy any emmissions or other EFI parts for your truck. I converted mine to a newer mass air setup, so I likely have have known good parts for yours. For instance, I know I have a good EGR control solenoid, EGR position sensor, and I'm pretty sure I have the EGR valve itself.

 

i use seafoam in everything it's a great cleaner and fuel stabilizer.i use it in my trucks,boat,quads,chainsaw,and mowers.it will clean the varnish out of the intake,throttle body,and injectors.

 

Thanks guys. I'll rip that stuff apart tonight and give it a good cleaning. I will pick up some gaskets in addition to the Seafoam. RI Truck, I also just noticed you were in Suffolk. Thanks for letting me know about your EGR parts. I'd like to buy them from you if they need replacing.