Scorp Fuel Pump

[davidb]

Here's the latest. I suspect the oil pressure switch was bad so the PO jumped
relay #8. Miss wired as well, had oil switch to sensor on the filter block back-
wards. Fixed that. Now the fuel pump doesn't get elec. straight from the
battery as before. Modest success. Then I attatcked the relays again.
The one closest to the firewall is relay #8 engine starting, next relay
is fast idle which I believe is solely related to the A/C [I think], lastly
is relay #7 which is running mode. I still get no activity from the fuel
pump [sound] w/the ignition switch. Checked fuse #1, fine. Now it gets
hilarious. My headlamp motor solely worked in the up mode before all this.
When I got halfway thru this fuel pump wiring/relay swap diagnosis, w/the
headlamps upright? I turned the Hella kill switch key on to see if the fuel
pump would make any sound, the headlamps lowered themselves. So my
fuel pump still doesn't work. My headlamps lower rather raise now. Anyone
want a almost re-furbed Scorpion? CHEAPPPPPPPPPPP !!!!

[DJ]

Two quick notes.

1. The fuel pump should NOT work just from turning on the key. It should only kick in once you've cranked the engine over enough to build up a bit of oil pressure.

2. When I got my car my headlamps would go up but not down. I thought it was on Viagra or something. I found that one of the two small 3 amp fuses on the right side of the fuse block was blown. Once that was replaced the headlights worked as designed. FWIW, the only place I've found that has those little fuses anymore is Vicks.

[davidb]

Thanks D.J. . Now that my headlamps are in the down position maybe
they are on Valium as opposed to Viagra. Amusing anaology nonethe-
less. Yes after review relay #8, pin #85, is connected to the starter
solenoid. Ergo no crankie, no juicie to Mssr. Fuel Pump. Thereafter
relay #7, pin #86 [running mode] acts as the safety device being
connected to the oil pressure switch. I'm glad I printed a few things
out from the CDs Will sent me before both my CD readers in my 'puter
shot craps awhile back. The fuel pump remains my priority yet it is
almost as though the headlamps are teasing me now: "fix me too,
fix me too". And yes the fuses are fine. I'm like you: ground 1ST,
fuse 2ND, 3RD God only knows how the PO messed up the wiring.

[Will]

DJ, I believe that your statement "1)" is, with all due respect, incorrect. It's been a while since I looked at the Scorpion wiring diagrram, but I believe that the fuel pump gets power from the starting circuit while cranking- regardless of whether there is oil pressure or not. This starts the car faster as the engine is not cranking and building up fuel pressure and THEN activating the pump, it's pretty much a standard from the wiring I have seen of different vehicles. Of course, I'm going from memory too which is markedly worse since the events of January.

[1,6 HF]

I'll admit to complete ignorance of Scorpion wiring, but Will's completely right about one thing: a typical starting sequence has an electric fuel energized and running either before or at the same time as the starter--not after the engine has cranked over several times to build some amount of oil pressure.

Unless you're using a pre-oiling system like an AccuSump, you simply can't escape the fact that you're initially cranking over a 'dry' engine with no oil pressure. In other words, whether or not you have fuel pressure, you're still initially cranking an engine that's only protected by the residual oil film. The only real difference is that DJ's method ends up running the starter for a lot longer until the engine catches.

With the typical race engine (and with any number of street engines), the sequence is exactly the reverse of DJ's method; the fuel pump is run for a few seconds to build fuel pressure before the starter is engaged.

[DJ]

DJ, I believe that your statement "1)" is, with all due respect, incorrect.

You're correct, I'm sure. I do remember reading both in the past, though and I wrote that without really thinking about it first. But it HAS to be cranking to energize the pump and that was my real point. It shouldn't run just from turning on the key.

[davidb]

I would think when you turn the key to accessory you should hear the
fuel pump click for bit to pressure up the system. Time to test the
relay block terminals for juice. I had the presence of mind to replace
the oil pressure switch when I was chopping down the oil filter/com-
pressor bracket while putting on D.J.'s alloy filter bracket. If my quess
is right that the switch was bad, causing the PO to start re-wiring
stuff, well I'm glad I got a new one. Man that thing is really buried.
To take that all apart again, alternator etc. AHHHHHHHH !!!!! Thanks.

[DJ]

I would think when you turn the key to accessory you should hear the
fuel pump click for bit to pressure up the system.

Nope. Not until you crank it over.

Off to the Automezzi this morning. Wish us luck!

[Will]

Nope. Not until you crank it over.

Off to the Automezzi this morning. Wish us luck!

Agreed. Good luck!!!!!!!!!!!!! :) :)

[John O]

I'll admit to complete ignorance of Scorpion wiring, but Will's completely right about one thing: a typical starting sequence has an electric fuel energized and running either before or at the same time as the starter--not after the engine has cranked over several times to build some amount of oil pressure...

Interesting. The Bosch injection system of the Fiat Spider and the X1/9 has this same sequence. Key to "on" position energizes the ignition system and the fuel pump. "Start" position energizes the starter motor. Release the key to the "on" positon and in a no-start situation, only the ingition system remains energized - no fuel pump. Though I've never tested it, I've always assumed the same thing would happen in an accident; fuel pump cut off.

My re-collection for the Scorpion with stock unmolested electrical system is like Will's: fuel pump in the "on" position, but everything is so frikin' by-passed now on my car, I could be mis-remembering (CRS).

John O.

[davidb]

I'm dropping this topic unless some miracle happens & I fix it myself.
Then I'll [re]post. Until then, me here in St. Lou, is gonna wait for
my local Lancia guru. I'll let it aggravate him. D.J. knows whom I'm
making reference to. Too many different opinions. Thanks all.