Fuel Head Pumps Switch Troubleshooting Help

[Ronnie's.930]

Among other K-Jet problems, my car has developed a situation where the fuel pumps run with the key in the "on" position even when the engine is not running/cranking. The problem is intermittent (sometimes does this and sometimes it works as it's supposed to).

- The metering disc is where it's supposed to be at rest.

- I tested continuity through the switch, and when the metering disc is at rest, there is continuity through the switch, and when the disc is pressed down even slightly continuity is lost - I assume this is how the switch is supposed to work?

- The switch plug looks to have two, tiny (Paul sized) brown wires - guess those are grounds, and if so, does anyone know where they lead?

- I've cleaned every ground connection I can find - even the multi wire ground point behind the fuel accumulator.

- Any ideas on how I should proceed to troubleshoot this (other than convert to EFI right now )?

* Does anyone know if that switch is tied into the overboost relay (yellow relay) - wonder if there is a problem there?

[krasuskyp]

convert to EFI right now

[Ronnie's.930]

Really weird - just cleaned the pins & sockets for the engine harness plug that attaches to the rear relay panel (one on firewall cleaned a few days ago), and also the the overboost relay pins/socket, and fuel pumps operate as normal (for now) - good for many tests. BUTT remains to be seen if this "fix" lasts.

Pretty much wild assed guessing on my part as I don't know if the fuel pump cut-off switch on the metering assembly is connected in any way with the overboost switch, and I've cleaned those bisches before . . . found some corrosion though, so assembled with some silicone grease this time.

[Ronnie's.930]

Originally Posted by krasuskyp

convert to EFI right now

Ha! I'm trying to figure out how to get that done, along with a Paul-style intercooler, too, ya' bisch!!!

[Ronnie's.930]

[T77911S]

make sure that green connector in your pic is plugged all the way in.
you can also do this.
with the key on, remove that connector. connect your meter to the 2 pins, you should have 12v.
then remnove the yel rly.
check 85 and 86 for power to ground. only one will have power
if that is good then check power from 85 to 86.
if that is not 12v then the sw in the AFM is not closing.
if it is good then the yel relay is bad.

if all is good with the meter on 85 to 86, you might bump the sensor plate a few times to make sure the SW cloeses each time the sensor plate returns to rest.

[jsveb]

I believe you need to include the engine bay (cotton swabs and all) in your detailing checklist.

[Ronnie's.930]

T77, thanks for all the testing info. At this point, I'm almost certain there is a problem with the overboost relay - fuel pump circuit worked as it's supposed to probably 20+ times in a row after yesterday's fumblings, but then the pumps again came on with just the key in the on position, so I pulled the relay, put it back in and no change, but then removed it again, shook it, put it back and it worked (real scientific, I know). I'll probably see if can take the cover off of it without tearing it up and sand/clean the contact points (will do the tests you outlined, too).

Jesper, right, I need to get the q-tipps (just the tips) in there or else my squeaky clean image will be subject to some serious scrutiny!!!

[Ronnie's.930]

In case anyone is curious, here's what the yellow relay looks like neekid' -

[T77911S]

good clear pic.

flip it over and let me see the solder side.

or
look for solder joints that have a thin circle around them
take a soldering iron and re-flow all the solder joints.

thats not really a charging/boost relay. 'it is strictly controlled by the AFM SW.
the ground for the 2 FP rlys does go thru it TO the over boost SW.

nice to see what is in there. i have never opened one.
a bit more than i suspected but this is probably where the short run of the FP's comes from when you first turn the key on.

[Ronnie's.930]

Here's the backside. I'm no judge of circuit board solder joints, but I think these look okay, right? Or is the fact that you can clearly see the "posts" in the center of some the solder blobs considered bad (mainly the larger ones) - is that what you mean by "thin circle"? I honestly don't think I trust myself to hit them with a soldering iron - too small (Paul?) and I don't have a steady enough hand for it . . .

I found three contact points that I cleaned with fine sand paper and cleaner spray, put it back in with cover off, and the pumps don't come on with just the key - that problem has been so intermittent, though, that I'm not confident the pumps won't come on with the key at any given time.

[Ronnie's.930]

Man, too funny how the simplest things get overlooked (or not looked at hard enough) by me . . . all it was is the pins (probably one pin) were not making good contact in the relay socket. The pumps started running again with just the key, so I tapped on the relay case while pumps running and no change, then I rocked the relay back and forth in the socket and could get the pumps to turn on and off that way. I simply opened the pins up with a tiny (Paul sized) screwdriver and now perfect.

I've had that thing on and off dozens of times over the years to clean the pins, troubleshoot other running problems and so forth, have always opened up the pins on other relays with a screwdriver, etc., butt guess I overlooked that until now. K-jetronic tool bag, chest, cart, rollaway right here!!!

[Hams930T]

Nice gloves.

EFI.

[Ronnie's.930]

Only poofters wear light blue or white gloves - black ones for me!

EFI bastage!

[Hams930T]

Originally Posted by Ronnie's.930

Only poofters wear light blue or white gloves - black ones for me!

EFI bastage!

I rock these bad boys myself: Nitrile Gloves Disposable Large

Makes routine maintenance a lot easier on the hands - and no post-work fingernail scrubbing necessary.

I get it!

- Chris.

[356911930]

HaHa..good one! I had the same thing happen to me with the front trunk relays.

Rahl

[mark houghton]

Originally Posted by Ronnie's.930

Only poofters wear light blue or white gloves - black ones for me!

EFI bastage!

So....I went to my doc the other day for my annual physical (it's been far too many "annuals" since my last one). I came fully mentally and physically prepared for the good ol' doctor-proctor to do his finger thing. But NOOOOO......they don't do that anymore, no more fishing around for whatever might be amiss "up there". I told him I was sorely disappointed.

It's a toss up....either that, or dealing with the yellow relay from hell.

[nickyclyde]

There is a product called Siltech I think ,sold by an outfit called Mapleshade. The stuff ,Siltech is fine silver powder in some kind of emulsifying grease and small batch made for electronic stereo connections , speaker wires and interconnects. It's expensive but I've been using it for years with excellent results. Mapleshade.com

[JFairman]

It looks like a couple of the solder blobs on the yellow relay printed circuit board were done quickly and it's possible there could be a cold solder joint in there. That could make resistance in the electrical circuit

It wouldn't hurt and might help to heat them with a narrow tip soldering iron until the solder melts and flows a little. Just stop when the solder melts so the components aren't heated too much.
If an electrical component on the circuit board shouldn't be over heated use fine tipped needle nose pliers to heat sink the wire or leg on the component side while heating the solder on the other side.
good luck with it.

[Ronnie's.930]

Nick, that sounds like an interesting product - so you put it on connectors, like the relay pins, and the silver helps make a better contact, right? I'm going to check that out, thanks.

Mark, how dare you STINK up my "pure as the driven snow" (thanks, Norm) thread with ASSenine, proctological buttwind, BUTT if you have your fart set on an old-school exam of yer neither region, then be ASSured that I know of a certain someone that lives in Connecticut, and another in Colorado, that will perform the age-necASSary tASSk free of charge! Hells, they'll even pay YOU for the opportunity to ASSist you!!!