Electrical gremlins

[Hatch]

They'll getcha everytime. Car started shocking me consistently everytime I got out.
Now the fuel pump wont work.
Think ive got a short/ground fault in the fuel pump wiring.. any ideas where the fuel pump relay would be on a BP swapped festy?

[FestYboy]

Same spot as a stock Festiva (driver fender), I'd also look at the roll over switch wiring as well.

[bravekozak]

Check if there is any bare, broken wiring touching the body. First pull back the rubber boot where the wire bends brtween the body and the hatch. If that is O.K., then remove the fuel pump access cover and check for bare wires. If O.K. then follow the wiring harness backwards under the carpet beside the drivers seat to the driver's door and then forward, up under the dash. It could be due to a hack wiring job, since your Festiva isn't stock. Always use open barrel terminals and connectors. Never use cheap butt splice crimp connectors. You will never have them pull apart and cause a short. Until then, wear rubber gloves.

[Hatch]

any idea what the stock fuel pump relay would look like? I pulled the driver seat and carpet, all wiring looks in decent shape. no obvious rub spots - everything is still wrapped in OEM wiring looms up to the firewall - on the engine side of the firewall things get a little more suspect but man, it's sooo hard to get at stuff right there in the driver side quarter panel...

[Hatch]

Fuel pump relays
All 3 seem to work

[ajpaynter]

Did you check the plug on the VAF? The fuel pump won't run if the VAF is unplugged. If you press the flap in the VAF the fuel pump should turn on.

[Hatch]

VAF = MAFS right?

[ajpaynter]

VAF = MAFS right?

Yes.

[Hatch]

Copy. Ill check it tonite. If I cant fix it then this festiva is getting a manual fuel pump switch.

[Greywolf]

What are you touching when you get zapped?

The commonest sense approach I can think of is to attach a meter lead to your battery negative, then connect a long wire to the positive lead, and begin probing different parts of the car body and such to see if there is a twelve volt flow anywhere.

Doing it that way points out where stray voltage is getting to with no guessing.

Once you find out where it's going, the next indicated step is to figure out how it got there, while testing for voltage with the same rig.

Another thing that it seems to me is interesting, is how come no fuses have blown. If there is 12V in the body, it means that the current flow is insulated to the battery return - otherwise it couldn't build up enough potential to zap you.

~ And that points to a bad ground.

STUDY THIS:
1) Electricity always follows the path of least resistance to return to it's source.
2) The human body averages 1,000 ohms of resistance (wet or dry)
3) If 1,000 ohms of resistance (your body) is the shortest path to return to the negative post - there's a bad ground

And that might be the whole problem...

The only way a voltage potential (static electricity) can build up is if it has nowhere to go.

~Check your grounds.

1) Battery to Engine
2) Battery to Body/Chassis


*I was an Aircraft Electronics Tech in the US NAVY for 20 years, and wound up being a RADAR SYSTEM Instructor. I have forgotten more things electricity can do than most people will ever even hear about.

This I know well, and hearken to it: "The simplest cause is always the true one"

I would estimate from my RV and Towing experiences also that 99% of all electrical problems were caused by a corroded or disconnected ground wire. EVERYTHING that uses electric power in the car, HAS to return to the negative post of the battery. It's the common tie-point.

If there are bad grounds, things that use power normally WITHOUT ANY FAULTS OR PROBLEMS can't find a return path through the chassis, engine block, or wiring.

~And that's how "ZAP" happens

There is another and less traumatic way to test for it:
Disconnect the negative battery cable.
Connect an OHM meter, or a multi-meter set to OHMS to the negative cable end.
Use the free test probe to measure OHMS to any convenient point on the Body, and Engine.

If you don't get a reading of ZERO OHMS, or as close to it as possible - make a ground wire and install it to the battery cable and the part that did not read zero, then test again.


THIS method is definitive

Any metal body part of the car chassis should be solidly grounded (ZERO OHMS) to the negative battery cable, so should the engine and transaxle.


***Another thing about that is, if you don't have a good ground return you can't get good power flow through the parts that use it - even if nothing is wrong with them.

[Greywolf]

VAF = VOLUME AIR FLOW
MAFS = MASS AIR FLOW SENSOR

~ It got me too, when I first got into these

Another one that tripped this old schooler was:
VACUUM DIAPHRAM = MANIFOLD ABSOLUTE PRESSURE SENSOR (MAPS)

SEE ALSO:

EEC
ECU
PCM

But anyway - I hope what I posted about ground returns is helpful to YOU and to everybody else on here - this isn't an isolated deal, it happens a lot.

It's called CORROSION (AKA: "RUST"), loose or forgotten connections can do it too
Watch for them

[Hatch]

Greywolf, thanks for taking the time to write up a great response! I agree with the KISS method - keep it simple, stupid
I replaced the engine/body ground last nite, and checked a lot of the little harness grounds in various places, but still no luck getting the fuel pump to run. I also replaced the battery to body ground with 2 gauge and sanded the contact patch to bare metal. (matter of fact, I sanded all the grounds to bare metal - some were only grounded through bolt threads because of paint)
I am pretty sure this is probably a result of the engine swap and subsequent corner cutting which means more corner cutting or a full overhaul. manual fuel pump switch sounds to me like an easy cut corner to get this thing going again.

[Greywolf]

Well - it sounds like you did the follow up footwork well on your own.

The next thing indicated is a "SYSTEMIC" look - you want to explore the schemo and the wiring to see if power gets where it needs to go, and how it travels from there.

By no means give up yet!

Now that the major factors are contained or controlled, it's time to take a closer look a the wiring JUST FOR THAT and see if there are any problems.

You hafta think:
"It works on a lot of other cars unless there is something wrong"


Something is missing, what you have to do is solve the puzzle as it stands.

I think the time is now to discover if any of it has been mis-wired.



The fuel pump schemo is pretty simple. If you have power out of the relay, does it get to the tank connector under the back seat? Check it at the connector under the seat. If it doesn't, think about the air door switch in the MAFS/VAF - follow it to there.

Check also the other side of the connector to see if it has a ZERO ground.

If volts get to the tank connect, and you have a good ground on the other side, it is in the tank..

(SCARY I know, but tests don't lie if you do them right)


It wouldn't be the first time in history that a fuel tank had to be dropped.


You can test the fuel pump (TANK SIDE) connector with a digital OHMETER for continuity. If it doesn't read very low, if it reads "INFINITE" then you either have a bad pump or the connections to it in the tank are bad.


Don't worry - a digital meter doesn't provide enough voltage to BLOW YOU UP!!! :tm:




~I will admit - the idea of an electric motor in a GAS TANK used to give me nightmares...


I went through a LOT with a Suzuki Swift - and the pump in the tank was the least of it.


If you get totally stuck and ate up, you can watch the playlist on my YOUTUBE channel about the frikken Suzuki...

*I think it's ready for a B6T now


This is a car that was sabotaged from the start by a punk poser:

https://www.youtube.com/playlist?list=PL3wwBuGjJXmLc-xqqj7i1-FhofTwYuAhx

[bravekozak]

Check your inertia switch. Make sure the button is in the down position. If you have a newer Festiva, the fuel pump grounds under the middle of the rear hatch opening.
Older Festivas had power flowing through the inertia switch.