Trouble code help
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Senior User
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From: South Texas
Trouble code help
My truck, an '87 Ford Ranger 2.3 5-speed, has been sputtering intermittantly so I decided to check for trouble codes. The computer spit out code 87 during the KOEO test, which according to my book is a "primary fuel pump circuit failure." So what exactly does this mean? What is this circuit? Anyone know where on the truck it is located and how I can test it? Any help would be greatly appreciated.
Post Fiend
Joined: Dec 2001
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From: South Jersey
Your lossing power to the fuel pump, you should run the pinpoint test, test the FP relay and trace the wiring, looking for bad coonnections damaged wires. If you need a wiring diagram or the PP test just let me know.
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From: South Texas
Is the fuel pump relay the one that runs a line from a relay in the engine compartment to the inertia switch inside the cab? Cause if it is I replaced this one a few years ago, but I guess it could be bad again. I would aprreciate some more information on that pinpoint test you mention and a wiring diagram if I'm wrong about the relay. Both pumps hum strong when I turn the key and both are only a few years old. Thanks again for the help.
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From: South Texas
Sorry it took me so long to reply to my own thread, my wife left town to visit her grandparents and she took my computer. I enabled e-mail and would really appreciate you sending me that test info. Thanks for the help.
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From: South Texas
Another question
Ken was kind enough to send me some great test information, but I have a question about it. To test the fuel pump relay the instructions say I need to connect a jumper wire from pin 22 on the relay to a pin on a "breakout box." What exactly is this breakout box and can I test this relay without one? I gather that it is something that you would connect between the wiring harness and the CPU, but is there any other way to test this relay? Can I just put a jumper between Pin 22 on the harness and pin 22 on the relay to get power flowing for the test?
Last edited by irishguyincc; Jun 5, 2005 at 02:45 PM. Reason: to add info
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Post Fiend
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From: Connecticut
It could entail a little more than just jumpering pins. Some of the pinpoint tests probably require that the harness connector be attached to the PCM, which of course is when using the breakout box is most desireable. In many cases, however, it's still possible to "backprobe" the harness connector and/or wiring to achieve the same result. Backprobing entails accessing the wire's end pin through the back of the attached connector with your DMM probe, or if that's not possible, then piercing the wire's insulation somewhere down the line with a sharp, conductive probe (some people use paper clips sharpened at the tip for this) in order to make contact with the copper wiring inside (and hence the circuit). The latter method is more crude but nonetheless it is still effective. A tiny dab of sealant can be used to cover any broken insulation.
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Senior User
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From: South Texas
So I replaced the fuel pump relay and the problem remains, seems even worse actually. One minute the truck runs fine and then it is suddenly starving for fuel, struggling bad. Also, I'm still getting the code 87. I'm pretty stumped here, anyone have anything else I can try? I imagine it's electrical, both fuel pumps are only a few years old so I would like to think they are not the problem. Surely the new relay isn't bad but I guess that is always possible. I even replaced the fuel filter just for fun but that didn't help either. The high pressure pump is audible when you turn the key so I know it's working then at least.
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From: South Texas
If the relay is working fine, what other things could be malfunctioning?
Today I checked wires, installed some new Autolite platinum plugs, and thoroughly cleaned the throttle body with intake cleaner. The truck ran fine during a little test drive, but a few minutes later when I drove it somewhere it lacked power again. The symptom was a bit different this time; instead of dropping off and then coming back the engine just constistantly struggled to gain full power, I was able to go about 50 MPH max. After a few hours of sitting the truck ran just fine all the way home, about 8 miles. Everytime I mess with it the symptoms seem to change slightly but the overall problem remains. I'm pretty stumped.
Today I checked wires, installed some new Autolite platinum plugs, and thoroughly cleaned the throttle body with intake cleaner. The truck ran fine during a little test drive, but a few minutes later when I drove it somewhere it lacked power again. The symptom was a bit different this time; instead of dropping off and then coming back the engine just constistantly struggled to gain full power, I was able to go about 50 MPH max. After a few hours of sitting the truck ran just fine all the way home, about 8 miles. Everytime I mess with it the symptoms seem to change slightly but the overall problem remains. I'm pretty stumped.
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From: South Texas
That was my first thought/hope. I think I got the problem fixed. I had to mess with some wiring from the relay to the fuel pumps, I put in some higher quality spark plugs, checked the wires and replaced the distributor cap and rotor. My cap was only a couple years old but the contacts on the inside each had a streak of corrosion on them, strange. I've driven it twice since all this and it seems to be running fine (mostly) for now, so I'm hoping I solved the problem.
On a related note, is there any way to test the distributor on this truck? Would a distributor fail intermittently, or would it just quit completely if it was going bad?
On a related note, is there any way to test the distributor on this truck? Would a distributor fail intermittently, or would it just quit completely if it was going bad?
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From: South Texas
Well after doing all of the above stuff the truck is driveable, but there still seems to be an intermittent drop off/miss just much less pronounced. I still have the code 87 and now have a code 67 in the KOEO test. Anyone know what the 67 is?
Also while I was checking stuff out I noticed a bit of a hissing sound coming from the area of the throttle body after shutting off the engine. I found that one of the four bolts that holds it to the intake manifold isn't tightening up. The bolt didn't look stripped or anything, but it doesn't tighten all the way. It's the bolt that faces the engine toward the cab. Is there anything I can do to make this bolt tighten up? Last time I bolted it on all four tightened fine, so I wonder what happened?
Also while I was checking stuff out I noticed a bit of a hissing sound coming from the area of the throttle body after shutting off the engine. I found that one of the four bolts that holds it to the intake manifold isn't tightening up. The bolt didn't look stripped or anything, but it doesn't tighten all the way. It's the bolt that faces the engine toward the cab. Is there anything I can do to make this bolt tighten up? Last time I bolted it on all four tightened fine, so I wonder what happened?
Cargo Master
Joined: Nov 2004
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From: Friendswood, Texas
I'd pull the throttle body back off and investigate the loose bolt. I suspect you have a vacuum leak because the bolt isn't tightening all the way. You may be able to use a helicoil to fix it if it isn't stripped too badly.