Okay so I was driving my ‘86 BII home from work the other night. (This is my daily driver, I’ve had no problems with it lately.) Any ways I pulled into a convenience store to get a drink; I noticed who the clerk was and decided that I wasn’t that thirsty so I just headed for the other drive to leave. As I turned the corner in the drive to leave my truck died. I tried to restart it and it cranked fine but just wouldn’t start. I kept trying to get it to start until it finally started losing power and was having a hard time cranking. I got the truck home charged up the battery and it is still acting the same. I pulled the middle plug wire on the drivers side and tested the spark with an old overheated sparkplug. I didn’t have any problem getting a spark - it was bright orange not blue but it still sparked easily. When I crank the engine it turns over but doesn’t even try to start.

What do you guys think I should look at first?

 

Well, I’ve checked the three plug wires on the drivers side and I get a spark from all of them. I took the air intake hose off an sprayed starting fluid into the intake and the truck started right up. As soon as the starting fluid was used up the truck died. So I’m assuming the problem is with the fuel delivery. Other than changing the fuel filter (which I did on this truck not to long ago) I’ve never dealt with fuel delivery problems where should I start?

 

I checked the power leads going into the frame mounted fuel pump with a test light and got no power so I traced the lines up to the drivers front fender across the engine down the pasangers front fender to the inertia switch. I had no power there either then I traced the wires back up the passangers front fender to what looks like a relay. I'm assuming that it is the fuel punp relay it is a green plug type box under the air filter housing it has a cube shaped black box on top; it is about the size of a todlers fist. It has about four wires goin into it one from the inertia switch and one red one and I think a yellow one the "relay" is in realy bad shape it is all caked with gunk. the wires are in bad shape also most of them have about 1/2 to 3/4 inch of insulation pealing off of them and the red one appears to have ben spliced the strands are actualy tied together. the red one has power when I put the test light to it but none of the others do.

 

I took the relay to the auto parts store and got a new one. Turns out it was the ignition relay not the fuel pump relay. That didn’t work so I then I replaced the actual fuel pump relay. That didn’t work either. So now I’m back to having no power at the fuel pump and not knowing why.

 

This is my ‘86 that I’m having problems with. I couldn’t figure it out so I took the two relays off of my ‘87, put them on my ‘86 and it started great. Then I replaced one of the relays with the original one and the truck still started. I then replaced the other relay with the original and it didn’t start. Naturally I pulled the original off put it in the “bad relay” pile and put the relay from the ‘87 back on. The truck started just fine.

(I’ll make a note now the “bad” relay had five blades)

So then I go back to the ‘87 put one relay back on (this one had originally came from this truck). Then I put a new relay on to replace the one that was still on the ‘86 truck. This truck started fine and runs fine.

So I think that I’ve got the ‘86 starting now. I played musical trucks in my driveway so that I could change shocks on the ‘87. Each time I started either vehicle they start and run fine. And I can hear the fuel pump hum when I turn the key.

Later on last night I took the family to the store in the ‘86. When I come out of the store it starts but then it stalls. I restart with no problem and pump the gas and rev the engine a few times while I’m waiting for my wife who is still in the store. After a sort while it runs fine. I drove to a few stores last night with it and each time after the first store it started and ran fine. This morning I take the truck out and it starts fine but as start driving down the hill that leads from my house the truck stalls and wont start. No humming from the fuel pump!

The first time that this happened was when I was driving downhill also.
I really hope some one can tell me what the heck is going on.

The first relay that I pulled off (which I’m guessing is not the problem) has four blades and plugs into a connector with four terminals. The second (“bad”) relay had five blades but only four terminals in the connector the good relay from the ‘87 that I replaced it with only had four blades.

 

The five blade thing doesn't concern me, other than it indicates that relay has been replaced with an aftermarket "generic" relay. These are pretty standard five pole relays, just that Ford doesn't use the fifth terminal for anything.

The stalling/no start still seems related to no power to the fuel pump? You've spent a lot of effort on the relays, assuming the wiring is in good condition (unless I missed something). You indicated when you probed the relay socket, that only the red wire had power. Assuming your '86 is wired like my '87 was, that red wire comes form the EEC relay (what you called the ignition relay) and powers the coil side of the relay. The yellow wire should be hot at all times. If you don't have a wiring diagram, I'd suggest getting one -- even the ones in Chiltons (which are also available in the vehicle repair guides at autozone.com) are adequate for this part of the circuit. If you don't have power to that yellow wire, I'd say the fault is between the relay and the battery (maybe a fusible link making intermittent contact or something else corroded out).

 

The harness in my 87 ranger developed a short between the inertia switch and the fuel pump supply wires. The fuel pump relay should be the one closet to the battery. It has 4 wires going it. two thick wires, and to heavier gauge wires. One of the thick wires should have 12v to it all the time, the other only when the relay is engaged. If you trace the wires from the fuel pumps up, you will see they going into this connector that turns 1 wire from the harness into two wires for the fuel pumps. I chopped the connector off from the harness, spliced a wire into the single-wire portion of a connector, then ran it over to the fuel pump replay and splice it into the wire that only gets 12v when the relay is energized. Works fine now. Only thing is, if I roll the truck over the fuel pumps will not automatically turn off

 

If I remember right, one of the wires on the test connector can be connected to ground to turn the fuel pump (relay) on. If you do this and you still get no power, I am guessing that there are wiring issues you need to investigate. I would also consider repairing the relay wiring you mentioned. Not sure if you can get a connector pigtail to splice in, but that would be an option or you could possibly use a similar quick connect terminal to effect the fix. I recommend using the heat shrink-style 'weatherproof' connectors and heat gun to seal them up. I have also heard of the connector at the fuel pump itself getting corroded or otherwise causing issues as well.

 

I’ve got six relays. Two in each truck and two extras. Through processes of elimination (swapping the relays out in each truck) I’ve found that one of the relays is bad the other five seem to be good. I’ve cleaned up ands greased the connectors with dielectric grease and repaired and insulated the wiring. I don’t find any problems with the wiring when I check it for resistance or voltage. The fuel pump seems to be working every time that I test it now. While I was trying to get the truck to start Saturday in the freezing rain I remembered that the last time I had gotten gas was at a different place than I usually get gas from. I usually get unleaded with 10% ethanol (the truck seems to like that) this last time I got gas it was at a hole in the wall with just plane old regular unleaded. Now when I get the truck started It wants to sputter and stall after about 30-60 seconds. It will cough and sputter for about two or three minutes but if I’m working the gas peddle I can keep it from stalling. (If I get out of the truck to disconnect the battery cables it stalls.) Once it warms up it seems to run okay with only the occasional sputtering. The problem does seem to be worse going down hill but maybe that is because when I’m going down hill I have one foot on the clutch and one on the break and none on the gas. I’m thinking/hoping that the last time that I filled up I got some bad gas I’m thinking of putting some gas treatment in it driving the old gas out and seeing if the problem gets better with the next tank. I appreciate the help I will keep posting and let you know how it turns out.

 

My '87 used to stumble shortly after startup like that. Two things: 1) I found a TSB (I expect it applies to '86's as well) that said that a dirty throttle body/upper intake can do that. It doesn't take much to take the hose off and clean out the throttle body. 2) My O2 sensor was also bad. Diagnosis started by pulling codes from the computer. You only need a paper clip and a voltmeter/test light to get codes from these, and you don't have a CEL to come on when the computer senses a fault. I would almost certainly go pull codes and see if there are any fault codes that would point to a possible solution.

 

I bet your idle air control valve is sticking. When you start it, hold your foot steady on the gas, just enough to bring it to say 1500 revs, if it stays relatively steady then the valve is sticking or faulty.

Also when going down hill, its a good idea to keep the engine over 1400 RPM instead of just coasting down hill. If the gas pedal is not being pressed, and the engine is over 1400 RPM the computer turns off the fuel injectors

 

Jumper cables or the actual truck's battery cables? If the truck dies out when you remove either cable, then you probably have a bad alternator. These trucks do not seem to like not having a working alternator or bad ground connections.

I would have to agree with the dirty throttle body / intake, idle air control, and O2 sensor possiblities mentioned. You may also be having EGR issues as well. Only way to know for sure is to pull codes. You can clean up the IAC and throttle body / upper intake fairly easily - this seems to be something that needs to be done fairly regularly on these. I am still wondering why Ford has the PCV lines going directly to the intake / throttle body and not to the outside air inlet side of the air filter box as you would normally see on a carbureted engine. Let us know how things go!

 

It has to do with emissions. Instead of PCV gasses just collecting int the air filter, they want them to be burned. Another large portion of the crap in 2.9 intakes is the soot from the EGR valve.

 

It would probably be better to re-route the PCV stuff to one of the two vacuum trees on the upper intake manifold plenum and add better filtration, IMO, that being the case. Would create less build-up in the IAC and throttle body - but not the intake manifold and valves. I still think that the engine, if in decent shape, would still pull enough vacuum through the air filter. I don't think emissions would be that much of an issue running full synthetic oil in the engine, though. Oddly enough, I believe the 88- or 89-90 model BIIs and 88- or 89-92 model Rangers with the 2.9 have no EGR, if I am not mistaken. They also went back and forth having or not having EGR on the 4.0s as well, if I am not mistaken. It's also interesting that it took nearly 40 years for certain technology to be available as an option from the manufacturer (a la GM and their Hydro-Booster option on cars and trucks, technology that has been around since the late 60s / early 70s, to the best of my knowledge). I have also seen different water-injection set-ups that reduce a lot of the buildup and hydrocarbon emissions, another bit of technology that has been around a while.

 

Well I put some Lucas fuel treatment in (had about half a tank) and within a few miles it started running much better. I drove the truck around to use up about another 1/4 tank an then put my regular gas in and it's running like it always has. I do appreciate the help. When it is cold I do sometimes have some bucking when I shift into second gear. I probably should pull codes but I’ve got lots of other honey do's and the truck is running acceptable for me.