I have a 1987 Ranger 2wd, 2.9, 5sp that feels like it is cutting out when accelerating. The only code in the computer (KOEO) is 67, which according to the manual is neutral drive switch (NDS) circuit open. Any suggestions what to look for? Can the neutral drive switch be the problem?

 

The switch is to prevent cranking the engine with it in gear. A miss on a pull is usually spark or fuel related problem. If spark gap is too wide, it can blow out. If the fuel filter is clogged or the pump is wimpy, it might not be able to keep up with demand on a spirited go at throttle up.

 

Its more than just a miss. It carries on so bad sometimes the engine will quit running. Everything in the ignition system, plus, has been replaced (cap, rotor, wires, plugs, coil, tfi, pickup, tps, map, egr, egr relay). Been through it all. Fuel system also (both pumps, sending unit, injectors, filter 3X). All parts are Motorcraft or Ford, except the hp fuel pump which is Bosch and the fuel pressure regular that was purchased at NAPA. It all began trying to eliminate a hesitation on acceleration. That has seemed to clear up over time but although the two could be related what I have now is new. I'm at a loss. Wiring diagram shows the nds connects to the ecm. Didn't know what its purpose was or if it could be related to my problem. Begining to think one of the new parts is defective.

 

OK, good feedback, you've been busy on this puppy!!!!

Sounds like this is a new problem, maybe a result of your maintenance work. Now use your inductive timing light & fuel pressure gauge to determine whats going missing when it lays down on you when going at throttle up. Be sure to check fuel pump volume delivery rate over time & if its low, check operating voltage to the fuel pump & the condition of the wiring pins & socket connection at the pumps.

If you have computer trouble codes stored, they can offer up good trouble shooting clues, so scan it & post All code Numbers.

When it cuts out & the engine stops running, are the dash warning lights still lit???? If not, look for a battery cable connection problem on Both ends of Both cables. Everything needs to be clean, bright & tight. Maybe try a wiggle test on both cables on both ends, to see if you can make it run rougher, or stall. We only have 12 volts or so to work with, so it doesn't take much resistance in a connection to cause mischief.
I've seen problems on the cable clamp wire crimp connection, out of sight, under neath the insulation, where corrosion had set in & caused an intermittent high resistance connection. Cable & clamps looked perfectly normal, no corrosion, no looseness, but when wiggled it would cause problems. Voltage drop tests with your multimeter while wiggling a wire or connection is a good way to check the quality of an electrical connection, cable, or wire run.

Keep us posted on your trouble shoot.

 

Thanks for the input pawpaw. Had checked for codes a while back and had 21-ect, 24-act and 67-nds. Replaced ect sensor. Had compaired values between the ect and act and they were nearly identical but replaced the ect anyway. This time I had the same 3 codes. Compaired values again and again they were near identical. Replaced the act sensor, drove the truck a couple of times and rechecked for codes. This time only the code 67 was there. I'm thinking of pulling the distributor again and making sure everything is alright inside. I have had the truck for almost 2yrs, not a daily driver, and only put a couple of thousand miles on it. It would always crank over no matter what gear the transmission was in. It set for a very long time before my purchase and only has 89K miles on it. Could be corroded or broken wires. Everything looks good on the outside but it could have something going on under the insulation. Plan of purchasing a breakout box so I can check circuits and sensors.

 

Check out this site for your vintage engine managment system, it has all kinds of useful info we can use to trouble shoot. Fuel Injection Technical Library

When it acts out & the engine stops running, are the dash warning lights still lit????

 

I haven't noticed any lights. I can only assume they are. What is the significance of the lights? It has only quit 2x. Both times when I was pulling away from a stopped position. It always starts right up without hesitation.

 

If the dash warning light/s aren't lit when it stalls, it suggests a problem with battery cables, or their connections, or the computer power relay.

 

I have noticed the ecm power relay gets warm, warmer than the fuel pump relay. Not too hot to touch just warm. I checked for voltage at the relay with the engine running and everything was good. I would have thought the fp relay would have been warmer than the ecm but since it didn't get hot to the touch I just past it off as being normal.

 

The power relays are a known trouble maker, so you might try swapping a like relay not needed to run the engine, like the A/C power relay & see what happens.

 

Fuel delivery appears to be the problem. I had the engine running while I checked voltage at the relays and the engine quit running. Did a quick check of voltage at the relays and everything had power. I installed my fuel pressure gauge and restarted the engine. Fuel pressure at idle was 29 psi and after a few seconds the pressure started to dropped off to around 20 psi and the engine quit. Restarted and it did it again. Have not been able to dupicate in the driveway again. It did start to drop one additional time and I tapped the front of the fp regulator and it recovered. Coincidence? Maybe. The fuel pressure at idle is 29 psi and the needle quivers slightly at idle. Pressure does change with throttle opening. Engine does have a slightly rough idle and I attributed the fluctuations in pressure due to changes in vacuum. The thing that puzzles me is if it is the regulator why does the pressure drop off. I would think the pressure would remain steady until the throttle position changed. The regulator is a NAPA replacement installed 4/12.

 

Good trouble shooting find on the fuel pressure. Make sure the FPR vacuum line is fitting snug. Could be the FPR diaphragm, disconnect the vacuum line to it & apply vacuum & it should hold that vacuum & not leak down, or maybe a fuel pump, or voltage feed problem to the fuel pump. I believe yours has two fuel pumps, a low pressure one in the tank that feeds the high pressure pump on the frame rail, that pumps up the fuel rail & I believe this rig is also a return type system, in that unused fuel at the fuel rail is pumped back to the fuel tank, so that return line off the regulator needs to be open, not clogged up, kinked, or pinched closed.

Using your fuel pressure gauge attached to the fuel rail & its bleed hose, perform a fuel delivery rate over time test, to see how the pump performs.

If volume is lacking, try loosening the gas cap & see if it'll recover volume flow, if no joy, back probe & measure both fuel pumps operating voltage at the pump.

 

Yes, it is the return type system. It is finally acting up in the driveway. Did another test at the relay and all is good. Started engine, got underneath and listened to the fuel pumps. High pressure pump runs momentarily after the engine quits. The low pressure is much quieter and a little hard to hear, but it seems to run after the engine quits. Looking at the fp regulator as the problem. Pressure readings are inconsistent. Sometimes rock steady on 30 psi and other times it quivers around 29 psi. If the pressure drops and the engine starts to quit, pumping the throttle will usually get the pressure back and the engine it will recover.

 

How does the under load fuel pump operating voltage measure At the fuel pump???? Revving the engine will cause the alternator output to go up, so if your having a border line fuel pump operating voltage at idle, it might go up enough when you rev the engine to wake up the pump.

Could be the FPR, just because its sorta new doesn't automatically mean it should be taken off the suspect list, make it prove itself. Will pressure straighten up every time you thump the FPR???? If so, replace that puppy under warranty!!!! What happens to fuel pressure when you remove the FPR vacuum line & plug it????

 

I'm leaning more toward the fpr than electrical. The charging system is putting out over 14v at idle. The hp pump is new and is getting over 14v. Checked and verified. The rear pump and sender were replaced last year with a Ford unit. Going to stick my neck out here because the electrical connector is darn near impossible to get to to check voltage, but when it was replaced the connector was in good condition, made a good connection and locked in place. I gased up over the weekend and the tank is full of gas. Don't want to deal with that unless I have to. I'm thinking that working the throttle is changing the vacuum to the regulator, causing the diaphram to move, allowing pressure to build up again.