I began tinkering with the 86 F-250 today. It cranks but wont start. I'm not sure it has any gas as the guage read empty for both tanks. When I bypassed the relay I got some gas into the filter, but not enough to get to the carb. I also need to try this with a fully charged battery. I did use carb spray, but couldn't even get it to catch. Here's a list of items that were replaced by the PO.

Starter solenoid
ECM
Coil
capacitor
cap/rotor/plug wires
Distributor
ignition switch
Fuel pump safety switch
fuel filter
tank selector valve
fuel pump relay
fuel return valve

I was able to verify the replaced items, as they all look new and he gave me the old parts as well. I'm gonna try and bottle feed it next time and get my battery charged. I'm open to any suggestions, other parts to swap. I got nothing but time.

 

I'm no expert, but how about the fuel pumps in the tanks, or the main one?

 

confirm gas in the tanks first, 2 1/2 gals each. hot battery a must, ecm won't operate on less than 10.5 volts.check fuseable links, as many parts replaced, must be a power problem.

 

Have you checked to see if you're getting spark at the plugs? Might wanna check your coil. Also, check both ends of your coil lead (from the coil to the distributor). If either end is corroded, it will kill your spark.

 

Yes, I would check for spark first. If you have spark, and squirt a little fuel down the carb, it should at least sputter and try to go. If you have a little squirt bottle with a small hose, you can fit this over the bowel vent in the carb and fill the carb up. It will run for about a minute like that.

 

Yes, I would check for spark first. If you have spark, and squirt a little fuel down the carb, it should at least sputter and try to go. If you have a little squirt bottle with a small hose, you can fit this over the bowel vent in the carb and fill the carb up. It will run for about a minute like that.

 

You didnt mention replacing plugs... Maybe you just have an old set of plugs that need replaced.

I would then check and see if you are getting good spark.

What frank mentioned bout filling up the carb with gas would be the next thing id check.

 

Sorry if this sounds basic, but in order for a motor to start it needs, Spark, Fuel, compression and it needs this all at the right time.

So, when checking a wont start, check the basics,
Is it getting fuel? If not then put some fuel in it (starter fluid) and see if that gets it running or at least trying. If you can get it to try to run then trace down the problem in the fuel system.

Is it getting spark? If not, then start tracking down why, I usually start at the plugs and work backwards, cause looking at the condition of the plugs will tell you a bit about how it is running (or was). Check for loose connections, check to see if there is spark coming out of the coil to the distributor (careful this one will give you a shock - I used to hold on the the coil wire with insulated pliers just in case there is a break in the insulation might want to do that when testing spark at the plugs as well). Check firing order - did the PO get the plugs hooked up in the wrong order (wired them backwards, didn't start at the number one plug on the dist cap, etc)

If your getting fuel and spark, and don't have a reason to believe your compression is whacked (plugs don't look all oil fouled or burnt to a crisp) the timing may be the issue (timing chain or belt), way out of time etc.

Now, I quit working on cars full time back i the early 80s when they all started running on computers and I didn't have the tools or money to buy the tools to do everything.

But breaking it down by system sure made it easier for me to figure out at least where to start.

Oh, one more thing, is vacuum leaks, if you have fuel and spark, look around and plug all the holes, could be enuf to keep it from starting, though you should get it to try to start with starting fluid even if it has a few.

Dave

 

The PO didn't mention replacing the plugs, guess I should check the condition regardless. I'll get some gas, got 3 batteries charging right now and I need to find my in-line spark checker.

I have to store the truck at my parents place right now, I've left it on my trailer. No room at my place. I'll drag it back over tuesday or wednesday.

 

I finally got this thing to start. I replaced the ECM again and it fired up...for a second. I'm not getting fuel now, but thats easier for me to figure out than a lack of spark anyhow. It already had a new ECM and I still have the old one as well. I pulled the ECM out of my 85 F-250 and plugged it into the 86. I got it to idle for a bit using carb cleaner. I plan on bottle feeding it just to roll it around the field and then back onto the trailer to bring to my place.

 

You've mentioned running on "Carb Spray" and now "Carb Cleaner". You do mean Starter fluid right?? Cuz if you spray carb cleaner into the carb of a running motor it will almost kill it (well it will if ya keep spraying).

 

carb cleaner will burn and run when there is no gas behind it. starting fluid on the other hand will compress, and lock the motor up, not to mention wash the cylinders. psyco stang, check and clean all the grounds, pay special attention to the one on the drivers side behind the headlight on the core support. bad grounds make for no electric fuel pump on these trucks, have lived it.

 

I have some work to do with the fuel system. The PO did a hack job of replacing the selector valve. It's not even bolted to the frame right now, it's hanging by the wires and fuel lines. I'd rather get it to my place to work on though. It's sitting in a field full of goatheads.

 

I finally hauled it over. I used a jumper wire to get the fuel flowing. Funny thing is the fuel flowed for about 30 seconds then stopped. I can hear the pump going and the guage says the tank is 3/4 full but nothing is coming out of the line. I decided to bottle feed it for a bit just to get it going again. I got it started, ran for a few seconds then died...no spark again. I know it has good oil pressure, the last time we ran it my buddy said the guage was reading close to the H. Could this thing be killing ECM's? I have a friend coming over tomorrow to help me. I"m wondering if there is a short in a wire that goes to the ECM.

 

replace the neg battery cable, and check and clean all grounds. check the inside of the relays and where they plug in for corrosion. I had one one time that rotted off one of the posts in the ecm relay