Engine bucked at low speed, died and won't restart

[Natedog]

Last night on the way home my Ranger started running poorly. At low speed in the parking lot (in first or second gear) and then later coming to a stop in second gear at a stop sign, it started kinda bucking. The engine started jerking back and forth like if you were constantly on and then off the accelerator. The closer I got to home, the worse it was running and I saw the check engine light blink on and off several times.

When I pulled into my driveway I side-stepped the clutch and smoked both rear tires. I set the e-brake, popped the hood, and jumped out to look at the engine. After idling widly for about 30 seconds between about 600rpm - 1500rpm, the engine died and wouldn't restart. I could hear the fuel pump relay clicking back and forth alot when it died and just after. Then silence. When I turn the key to 'run' position I don't hear the fuel pump run like it should. It just cranks over and once or twice kinda barely tried to fire up. Mostly just cranks endlessly. I swapped out the fuel pump relay with a good used one and no difference (this relay is off my parts truck that ran when it was parked).

Hooked up my code scanner and got nothing with KOEO! Tried several times and nothing. Won't start, so cant do KOER tests. It was late and dark out, so I just parked it for the night and took the other car to work today.

I'm thinkin frame rail mounted fuel pump, fuel pump relay, fusible link? Suggestions please?

 

[1987rangerxlt]

Battery?

The battery is always a good place to start. Since you've been cranking it with no starting, it's probably discharged anyways. A fresh battery could eliminate one potential problem from your troubleshooting.

 

[KELLY88]

Fuel filter could be stopped up or the fuel pump could have gone bad. Could also be a bad ground, look for those before you start replacing parts.

 

[Psychopete]

When you hook up the scanner, you got nothing, and not 11s correct?

Sounds like the PCM was getting intermittent power until the point of not getting it anymore.

Double check the small ground from the battery. Double check the ground by the PCM, the harness into the PCM, power on pin #1 (yellow) on the PCM, and other various grounds. Pin #1 is HOT all of the time, the purpose of saving codes in CM and other calibrations that it calculates at runtime.

It might be worth while to check out the ECC relay as well. Do you power at the IAC when the key on? Looking at a diagram for an '88 (I know your's is a mutt), this is powered when the ECC relay is energized.

Glace at a wiring diagram to aid in where power is missing if in fact it doesn't appear that the PCM is getting turned on. And the fuel pump relay isn't going to come on unless the PCM is getting powered.

http://econtent.autozone.com:24991/znetrgs/repair_guide_content/en_us/images//0900c152/80/07/81/cc//large/0900c152800781cc.gif

FWIW, Most of the circuits here are usually pretty close, but the wiring colors can differ.

I would guess that a wire isn't making a good connection somewhere because of the intermittent switching of the relay.

Pete

 

[Natedog]

1987Ranger,
Battery is fresh Optima red top and is cranking it as normal and not even low or weak, therefore that should not be a problem.

Kelly,
Fuel filter is fairly new and does not affect the electrical operation of the engine...no fuel pump run at initial KOEO.

Pete,
When I hook up the scanner, the light is on (in the Hold position on scanner) until I turn the ignitiion key to on (KOEO) and then the code scanner light goes off and I waited a minute or two and nothing. Tried a couple times and nothing.

You recall correctly, my mutt was 87 and now is 1988 with CA BAR sticker on firewall. , A4LD to M5R1, and 4x2 to 4x4. .....mine uses the original 1987 harness with all necessary wires added/removed to make it a 1988 engine harness with the 1988 EEC-IV and all related engine sensors. You are also correct about the two harnesses being very close...1989 and newer get alot more changes. FWIW both my battery cables are new including the expensive NAPA stock replacement for the ground even includes the small single wire plug, intemediate ground lug for the frame rail and then the end lug for the engine block. Fuses under the dashboard are all good too.

It's been a long week and was very tired last night, didn't even check for spark although I'm guessing that is not the problem anyways.

WIll check all that you suggested, thanks for all the replies!

 

[Natedog]

Just checked it out and I have spark at the plugs when cranking. The red wire on the IAC has about 2.3 volts and the one bigger wire at the fuel pump relay has 12.25 volts. Small ground at battery looks fine. Going to check the ground and #1 EEC pin for power.

ANy other input?

 

[Natedog]

....It might be worth while to check out the ECC relay as well. Do you power at the IAC when the key on? Looking at a diagram for an '88 (I know your's is a mutt), this is powered when the ECC relay is energized....

After chekcing other stuff, I noticed that the brown relay (ECC relay, correct?) was more than a little warm to the touch while I was checking the voltages with KOEO and so I swapped it with a known good used one.....and my truck fired right up and runs better than it has in awhile!!! Gotta get another spare to carry now!

THanks for all the help!