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fuel pump Wiring hot at ALL times? by Lou6t4gto
Started on: 11-30-2018 03:21 PM
Replies: 16 (223 views)
Last post by: Lou6t4gto on 12-29-2018 06:20 PM
Lou6t4gto
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Report this Post11-30-2018 03:21 PM Click Here to See the Profile for Lou6t4gtoClick Here to Email Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post

the orange and black wires, at both the oil sender And FP relay are HOT at All times, Key even NOT on. Is it supposed to be that way ? OR is it supposed to be a "switched" line ? thanks

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Lou6t4gto
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Report this Post11-30-2018 03:24 PM Click Here to See the Profile for Lou6t4gtoClick Here to Email Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post

also, with the Key" ON", which wires on the relay Should be "hot" ? orange/black and tan/white ??? or it there a 3rd wire ? Thanks

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Lou6t4gto
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Report this Post11-30-2018 04:23 PM Click Here to See the Profile for Lou6t4gtoClick Here to Email Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post

shouldn't the green/white wire from the ECM be hot to "energize" the relay when the key is turned on ??? I cut the case off the relay, and If i manually press the contacts, the fuel pump will come on, so it leaves me to believe the ecm is not sending current to turn it on. Opinions ?? Thanks

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Raydar
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Report this Post11-30-2018 04:32 PM Click Here to See the Profile for RaydarClick Here to Email RaydarSend a Private Message to RaydarEdit/Delete MessageReply w/QuoteDirect Link to This Post

The fuel pump fuse is definitely wired "hot". It's why a stuck oil pressure switch will turn your battery into a doorstop.
I rewired mine at the fuseblock. Haven't had a dead battery due to a fuel pump running, in years.

Some people will recommend against doing this, for current capacity reasons, but it's never caused me a minute's trouble.

Edit - I believe that Terminal G on the ALDL is the fuel pump enable line. If you run 12 Volts to it, even with the key off, I'm pretty sure the pump will run. I don't know which side of the relay it connects to, however.

[This message has been edited by Raydar (edited 11-30-2018).]

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theogre
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Report this Post11-30-2018 05:38 PM Click Here to See the Profile for theogreClick Here to visit theogre's HomePageSend a Private Message to theogreEdit/Delete MessageReply w/QuoteDirect Link to This Post

FP Relay is Hot all the time on FP contacts.
Yes, that and other things can ruin a battery fast. And ruin what even like the FP itself in this case.
ALDL G is wired after the relay to tell if relay works or to power the FP to drain the tank etc.

Rewired fuse box is an iffy idea... I switch already handles a lot of power and FP needs 7-10 amps more.
Iffy I switch can cause low volts and kill anything run by it. Pushing the switch to handle more power often only makes worse problems and sooner.
See my Cave, Electric Motors

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Lou6t4gto
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Report this Post11-30-2018 06:57 PM Click Here to See the Profile for Lou6t4gtoClick Here to Email Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post

what I Have is full time power to both the oil sender and the relay. the relay will NOT turn on the fuel pump, but the oil sender(which I'm almost sure is bad) keeps it running constantly as long as the battery is connected.. I cut off the case of the fp relay, and if I push the Contacts closed, the pump runs. but, SHOULDN'T the ECM supply Power Through the green white wire to energize the relay >because the green white wire is doing Nothing, key on Or Off. I AM changing BOTH the oil sender And the relay, so I'll see if that helps the situation. Thanks

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theogre
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Report this Post11-30-2018 07:24 PM Click Here to See the Profile for theogreClick Here to visit theogre's HomePageSend a Private Message to theogreEdit/Delete MessageReply w/QuoteDirect Link to This Post

ECM switches to ground to turn on most relays etc.
but in FP relay case, ECM switches Power to Dr Grm/wht wire.
If no start/run then ECM turns that off after ~ 5 sec. if started after then turns on the relay again.

If has AC, just switch relays. Both are same.
If you never get power to dr grn/wht wire then ECM or plug to it have problems. "Dead" ECM commonly seems to run but 1 circuit is dead from solder crack(s) etc. Even if you could find a crack joint and fix it... you very likely won't fix the ECM because you fix 1 and isn't the bad one causing the issue at hand this day.

OP sender is bad to run FP w/ engine off. Better is just upgrade 87 and older cars to 88 sender. See my Cave, Oil Sensor

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Lou6t4gto
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Report this Post12-01-2018 12:13 AM Click Here to See the Profile for Lou6t4gtoClick Here to Email Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post

OK, tried for "power" at #3 clear at ECM, I have power for 2-3 seconds when key is turned on. And power At the relay for 2-3 seconds. But the relay will Not "turn on" the pump. I've tried 5 different "Used" Relays,... nothing. will get a NEW Relay tomorrow.

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Lou6t4gto
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Report this Post12-01-2018 05:49 PM Click Here to See the Profile for Lou6t4gtoClick Here to Email Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post

The Ground wire going "Into" the relay was Not "Grounding" !

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tomsablon
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Report this Post12-02-2018 08:46 AM Click Here to See the Profile for tomsablonClick Here to Email tomsablonSend a Private Message to tomsablonEdit/Delete MessageReply w/QuoteDirect Link to This Post

Had a bad oil pressure switch go bad on mine . after i'd shut of ignition the pump would continue.

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Lou6t4gto
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Report this Post12-02-2018 01:51 PM Click Here to See the Profile for Lou6t4gtoClick Here to Email Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post

that is the OTHER problem with the car. I'm waiting for the oil sender to get here. LOL

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Raydar
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Report this Post12-02-2018 03:04 PM Click Here to See the Profile for RaydarClick Here to Email RaydarSend a Private Message to RaydarEdit/Delete MessageReply w/QuoteDirect Link to This Post

 
quote
Originally posted by theogre:
....
Rewired fuse box is an iffy idea... I switch already handles a lot of power and FP needs 7-10 amps more.
Iffy I switch can cause low volts and kill anything run by it. Pushing the switch to handle more power often only makes worse problems and sooner.



Mine has been that way for several years, with no problems. If I were using a high capacity pump, I might re-evaluate the decision, however.

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Lou6t4gto
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Report this Post12-25-2018 02:06 PM Click Here to See the Profile for Lou6t4gtoClick Here to Email Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post

Put on the" new sender", now it primes, then shuts off 'till started.

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Lou6t4gto
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Report this Post12-28-2018 06:35 PM Click Here to See the Profile for Lou6t4gtoClick Here to Email Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post

IT PRIMES, then it" cranks" Until it has about 20 PSI of "OIL PRESSURE", then will start. it holds 50 PSI of "fuel pressure" as soon as the key is turned on, and never drops a pound after shutting the key off. The only way it will "Start" without" cranking it for 20 seconds" or so , is to give it a shot of" Quick Start", at which point it starts Immediately. If it "HAS Fuel Pressure", WHY will the Injectors,NOT INJECT, until the Oil Pressure goes up ?

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theogre
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Report this Post12-28-2018 07:06 PM Click Here to See the Profile for theogreClick Here to visit theogre's HomePageSend a Private Message to theogreEdit/Delete MessageReply w/QuoteDirect Link to This Post

So ALDL G is off too (Test light from G to Ground) ?
ECM is likely bad or have other wiring problems.

Iffy parts/connections to/in the distributor and rest of ignition can cause fuel problems because ECM can't reliability see them or ECM internally has same issue.
Pull Tach Filter and check rest of HEI.
See my Cave, HE Ignition and Ground "Myth" notes

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cmechmann
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Report this Post12-28-2018 08:13 PM Click Here to See the Profile for cmechmannClick Here to Email cmechmannSend a Private Message to cmechmannEdit/Delete MessageReply w/QuoteDirect Link to This Post

With the tach "strangeness" you mentioned earlier(other post) I would also check for a tach filter issue as Ogre suggested. On my 3800, I am not using a filter for the tach. The tach is driven off the white wire from the 3800 module.
You are going to need to use your noids you mentioned, and check for injector pulses while cranking. Something is odd here. Especially if it will run good after an Either shot. PCM controls the negative side of the injectors. Unless the positive side is being drawn down someway.
Did you check the injector wiring to make sure someone didn't wire them to the oil pressure sender during the swap. I know it sounds off.
Sounds like you need to carefully review the wiring diagrams I posted before. Make a check list and go over all of them. Concentrate on Phonedawgz.jpg. Very good swap diagram. This also shows how to bypass the oil sending unit. This shows what has to modified on the 3800 harness. The rest of the wires, that don't show connections are ones that don't need to be modified on the 3800 harness.

[This message has been edited by cmechmann (edited 12-28-2018).]

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Lou6t4gto
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Report this Post12-29-2018 06:20 PM Click Here to See the Profile for Lou6t4gtoClick Here to Email Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post

cmechmann, sent you a PM

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