1988 ranger. Fuel pumps stay running

Farkhaed1 · Oct 5, 2015

Ranger is currently not starting. Have spark and fuel. But I'm mostly wanting to find out why when the key is turned on the fuel pumps continually run and do not shut off. Thought possibly the filter and the fuel tank strainer could be clogged and the pumps were not getting enough pressure. Replaced both those parts and checked fuel pressure at the rail. Good pressure at the rail, but still no luck. Also, when I unplug the inertia switch the pumps still run. Shouldn't they shut off when the inertia switch is disconnected? I'd rather figure out the problem instead of buying parts and hoping it fixes the problem. Any help/ideas are much appreciated.

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huh? · Oct 5, 2015

could be someone "customized" the fuel pump circuit. try pulling the plug on the relay. if they still run then it may be rewired completely independent of the ecm grounding control. you might have to slide under the truck and follow the wires back from the tank to see if any non-factory wiring is there.

with spark and gas pressure i'll assume injectors not operating. you can check on that by squirtin' something flammable into the throttle body and cranking the engine. if the spark you got fires whatever you spray in there then spark strength and timing is good.

since both injectors and pumps are supplied a ground by the ecm try remove the negative battery cable then the harness at the ecm and check for continuity between the neg battery cable clamp and pins 20, 40, and 60 on the harness

Farkhaed1 · Oct 5, 2015

huh? said:
could be someone "customized" the fuel pump circuit. try pulling the plug on the relay. if they still run then it may be rewired completely independent of the ecm grounding control. you might have to slide under the truck and follow the wires back from the tank to see if any non-factory wiring is there.

with spark and gas pressure i'll assume injectors not operating. you can check on that by squirtin' something flammable into the throttle body and cranking the engine. if the spark you got fires whatever you spray in there then spark strength and timing is good.

since both injectors and pumps are supplied a ground by the ecm try remove the negative battery cable then the harness at the ecm and check for continuity between the neg battery cable clamp and pins 20, 40, and 60 on the harness

Yea, bought it from this guy and he had said there was some wiring issues. I'll check what you said this evening. Thank you

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Farkhaed1 · Oct 6, 2015

Okay. Pulled the relay and pumps kept going. I found a black wire going from the closest pump to the engine to the ignition wire that plugs into the coil. I tried checking pressure again but the pressure gauge I rented did not work. I rechecked the fuel line after the fuel filter to see if it was getting gas and it was. I pushed the shrader valve in and it shot fuel to the hood. So I know I'm getting fuel up to the rail. It wants to start while spraying starter fluid into the TB. I checked my plugs again and the spark looks weak. I don't think it's a spark issue since it did start a couple days ago but quickly died.

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Andy D · Oct 6, 2015

Farkhaed1 said:
Okay. Pulled the relay and pumps kept going. I found a black wire going from the closest pump to the engine to the ignition wire that plugs into the coil. I tried checking pressure again but the pressure gauge I rented did not work. I rechecked the fuel line after the fuel filter to see if it was getting gas and it was. I pushed the shrader valve in and it shot fuel to the hood. So I know I'm getting fuel up to the rail. It wants to start while spraying starter fluid into the TB. I checked my plugs again and the spark looks weak. I don't think it's a spark issue since it did start a couple days ago but quickly died.

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Try this, take the black wire running between the fuel pump and the coil off. Put the relay back in and try to start. Report back

Farkhaed1 · Oct 6, 2015

Andy D said:
Try this, take the black wire running between the fuel pump and the coil off. Put the relay back in and try to start. Report back

If black wire is disconnected then there is no power going to the pumps.

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Andy D · Oct 7, 2015

OK ,The black wire to the coil isn't factory. But with it off ,the pumps don't run. So the factory system is broken. I would start at the pump relay socket. Jumper battery voltage, which should be at the socket, to the pump power. I would google up the socket's pin out and the part number for the relay. Also check the inertia switch. I wish you the best of luck with that beast.

Farkhaed1 · Oct 7, 2015

Thanks I'll check that. Do you think that since the wire that supplies power to the fuel pump is spliced into the ignition wire it could be giving a constant stream when the key is turned to the pumps making them constantly run while the key is turned? I don't know why I never thought of that before...

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huh? · Oct 7, 2015

reads like you understand the pumps always on situation.

i would vote on following Andy Ds' lead regarding the wiring.

removing the fuel pump power parasite from the coil power supply wire may beef up the spark a bit, too.

original engine in there?

Andy D said:
... beast.

hah! first time i opened this thread the other day the first thing that popped into my mind was that the owner needs a couple seat belts on the front bumper there. taking a leisurely ride home from a picnic dinner in the mountains with the missus along a dark winding road. BAAMM!!! THAT'S RIGHT, YOU JUST NAILED BAMBI'S 12-POINT UNCLE!!!!!!!!!!!!!! all Farkhaed1
would then need to do with his "heavy heart" and "burden of sorrow" is walk around to the front of his 'beast', lift that trophy onto that monster of a tenderizer, belt it in and beat it.

Farkhaed1 · Oct 7, 2015

Awesome! That could be the culprit!

Bumper is pretty gnarly.

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Farkhaed1 · Oct 13, 2015

Okay, no success on Andy's lead. What I have come to is that it is in fact not a fuel problem at all. I replaced the plugs and kept the fuel pump power spliced into ignition wire and with new plugs the spark is a lot better. If the ICM was bad would there be no spark at all?

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Farkhaed1 · Oct 14, 2015

Checked the injectors and didn't get any ticks from them. Tested ecm and it was dead. Thanks for all the help guys!

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1988 ranger. Fuel pumps stay running

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