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Speed Junkie
 
Join Date: Jul 2004
Location: MI
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1989 930 - Won't Start - No Fuel

I just recently put an engine back into my 930 after 6 years in storage. I tried starting it and the fuel pumps won't kick on. I can get them to run when I jumper the the #87 & #30 pins on the fuel relays. What could be causing this problem? I swapped the relays around to see of the problem goes away, but it doesn't. So I assume its not the relays?

Please help!

Old 06-26-2010, 10:30 AM
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Speed Junkie
 
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I jumpered the yellow relay in the engine compartment and the fuel pumps work. I believe this relay is the overboost cutout? Can I drive the vehicle with this relay jumpered?
Old 06-26-2010, 12:59 PM
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Yes you can drive with it jumpered.

It's been said the yellow relay is the overboost sensor relay forever on the forums but on my '87 it has nothing to do with that. The overboost sensor wire will still shut off the pumps with the yellow relay jumped. Also if you jump the same pins on the yellow relay as the red relays in front you'll burn up 2 wires and eventually start a fire under the relay panel if you don't notice the smoke from the burning wire insulation.

Apparently the overboost sensor is tied in with the speed relay which has 2 small 12 volt relays inside it under the driver seat on my car and the yellow relay is hooked up to the blue airflow safety switch next to the air flow meter.
Pulling the plug off that switch should trip the yellow relay, grounding the 2 front red fuel pump relays and make the fuel pumps run with the ignition on motor running or not.
Old 06-26-2010, 01:24 PM
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Quote:
Originally Posted by JFairman View Post
Yes you can drive with it jumpered.

It's been said the yellow relay is the overboost sensor relay forever on the forums but on my '87 it has nothing to do with that. The overboost sensor wire will still shut off the pumps with the yellow relay jumped. Also if you jump the same pins on the yellow relay as the red relays in front you'll burn up 2 wires and eventually start a fire under the relay panel if you don't notice the smoke from the burning wire insulation.

Apparently the overboost sensor is tied in with the speed relay which has 2 small 12 volt relays inside it under the driver seat on my car and the yellow relay is hooked up to the blue airflow safety switch next to the air flow meter.
Pulling the plug off that switch should trip the yellow relay, grounding the 2 front red fuel pump relays and make the fuel pumps run with the ignition on motor running or not.
Had a weird thing happen to me today...changed the oil, ran it till warm to check the level, shut her down and started back up an hour later to go to town. Crank crank crank....$h!t, she won't light up. Go figure, the first time in a couple years I've had any starting problems. So, left the key in the on position, popped the engine lid, pushed down on the metering arm, and I could hear the infamous yellow relay clicking but no fuel pump action. Swapped out with my spare "yellow" and same story. Checked the pump fuse up front and relays...all good to go. The only thing I didn't check - because I can't get to it easily - was the boost pressure sensor switch to make sure the ground connection was good.
Pissed, of course. Last resort: Fish around in the glove box for my custom Yellow Relay jumper wire, pull the relay and jump between 87 and 87A. Shazzaammm....the pumps run. Cool, I say. Yank the jumper, stuff the yellow ***** back in, and she starts and runs just fine.
WTF, I must have a bad ground or something somewhere. Once I got the pumps running, it probably arch-welded the poor connection wherever it is. May have to explore under the seat and check out the speed relay.
Of worthy note: I still say that jumping pins 87 and 87A on the yellow relay will make your pumps run with the ignition switch on (as I confirmed once again today). Maybe the confusion we've been bantering around is the difference between jumpering 87 an 30 on the fuel relay(s), vs. 87/87A on the yellow relay.
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Old 06-26-2010, 06:37 PM
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I have written down on my yellow relay which pins I jump and i put a red dot next to positve and a black dot next to ground on the metal next to the relay cocket and I'm not going out in the dark and taking off the cover to look right now. I don't know what post I wrote down which ones I use either..

Whatever works, if yours is right then my car is wired different. I still don't know what all that **** yellow relay is supposed to do and I don't read electrical diagrams so maybe someone that really knows will enlighten me someday.

I think it only shuts off the fuel pumps when the blue sensor plate switch is unplugged or the plate is moved downward. My yellow relay has nothing to do with overboost fuel pump shut off.

I used a voltmeter to find polarity and decide which pins work best for jumping on mine after trying the same ones you use on the front red relays and that was definately not it on my car.
Old 06-26-2010, 06:57 PM
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OFF THE BOOST PIPE NOW...
 
A930Rocket's Avatar
 
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IIRC, I pulled my yellow relay while the car was running and noticed no difference. Pulled the delayed run in relay and it wouldn't run or start.
Old 06-26-2010, 07:03 PM
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Rocketman, I thought you yanked the yellow a long time ago and went with a straightforward direct pump wiring and impact switch for accident emergencies? Car shouldn't run with the yellow pulled.

Mysteries. Had a few free minutes this morning, and did the following:

- turned the key to on, pressed down on the metering arm via the mixture adjustment post, and the pumps started. The same holds true by pulling the blue connector to the arm switch.
- pulled the yellow relay, pressed the metering arm...and pumps wouldn't run. No suprise.
- jumped across pins 87 and 87A, and pumps instantly started (without having to delfect the metering arm)
- jumped across pins 87 and 30...nothing
- jumped across pins 87A and 30....pumps instantly run without having to depress the metering arm

What I don't know yet - 'cause I can't reach without taking off the IC - is whether either of these jumping scenarios will allow the pumps to run when the overboost sensor switch wire is pulled (interupting the ground connection there). I've always assumed that both the relay and switch work in concert with the Devil to stop the pumps in overboost situations....I think. But per Jim, with a removed yellow and jumpered connections, the OB sensor will still shut off the pumps. So, what the hell good is the yellow thing?

Anyway Jim, it seems both of us are correct on which pins to jump...you have two choices: 87A/30 or 87A/87.
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Old 06-27-2010, 07:43 AM
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I don't know how the thing is wired but maybe there are 2 sources of 12 volts to the relay like most relays... that is the whole purpose of using a realy. One for triggereing the electromagnet coil windings of the actual relay on the circuit board inside and another higher amperage source of 12 volts to supply power to the contact points of the relay and turn on or turn off some device.

All I know is when I had the yellow cover off the thing and using a digital volt meter to measure the contact points of the actual miniature relay on the board, they were connected to the pins I use for jumping when I have jumped it and the pins io jump are not next to each other there is one pin in between them.

I would have to go out and take a picture of the relay socket to show which pins I jump because the actual rubber relay socket pins are not labeled and the pins on the relay itself are not labled.... the diagram with the pin labels is printed on the side of my yellow relay in black ink and I don't know if that diagram correlates to the male relay pins or the rubber sockets female pins.
Old 06-27-2010, 09:20 AM
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OFF THE BOOST PIPE NOW...
 
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Everything has been left in place (except what was under the drivers seat) when I was using the MSD6AL. When my car wouldn't start, I went back to the stock CDI. Still haven't checked the MSD any further to see if that was the problem.

With the inertia switch install, and using the CDI again, I thought I would clean up and remove all the electronics in the corner (overboost relay, delayed run on relay, windsheild heater relay, etc. ) and after remvoving it all, it wouldn't start. Only with the delayed run on relay connected did it run, so I just re-installed everything...
Old 06-27-2010, 10:45 AM
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Here's some pics to try and show which pins I jump in the yellow relay socket to make the pumps run without it.

I have a red dot on the aluminum panel next to the rubber relay socket female pin where I measure 12 volts positive and a black dot on the panel next the the rubber relay female pin that is ground. These are the two yellow relay socket pins I jump to make the fuel pumps run without the yellow relay.

When only these 2 pins are jumped the pumps run and the cream colored overboost sensor will still shut off the fuel pumps. If I pull the white wire off the overboost sensor the fuel pumps will still shut off with no yellow relay while those 2 socket pins are jumped.

This tells me the yellow relay has nothing to do with overboost protection shutting off the fuel pumps.
I believe the speed relay under the driver seat does that function. There are 2 small relays on the board inside what pelican parts calls the "speed relay" I think this relay is also the factory rev limiter that shuts off the fuel pumps abruptly somewhere around 7200rpm.

It seems to me the yellow relay only works with the safety switch on the air flow meter to shut off the fuel pumps when the engine shuts down and stops in sucking air while the ignition is on.

Pics of the yellow relay next to it's rubber socket and in the relay in the socket.
Red and black ink dots are next to the yellow relays rubber socket pins I jump and a pic of the cover off the yellow relay showing the actual miniature relay with it's dual contact points which are closed at rest on it's circuit board:



Hopefully this overdone description clarifies and shows which yellow relay socket pins I jump.
Also keep in mind the rubber relay sockets will rotate in the panel holes they are installed in so mine may be rotated to a different position than stock but that doesn't change which pins do what or get jumped to bypass the relay.
Old 06-27-2010, 11:00 AM
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Speed Junkie
 
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I replaced the Yellow Relay with a new one from Pelican Parts. Unfortunately, the new relay made no improvement. I still have to jumper the pins on the Yellow relay to get both fuel pumps to run. I tested both relays and they are functioning properly. Any thoughts on what might be going on?
Old 07-28-2010, 09:17 AM
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Could be the airflow sensor plate rest height needs adjustment to make the blue safety switch and yellow relay work correctly... I say maybe though.

If the green plug on the blue airflow sensor plate switch is good and the blue AF sensor plate switch is good then maybe the height of your airflow sensor plate at rest while there is control pressure pushing it upwards needs to be adjusted.
The round air flow sensor plate should sit right even with the narrowest point in the venturi like metering cone the air flow sensor lives in on the 930 CIS airflow housing while fuel pumps are on and control pressure is holding it up all the way.

If it's at the wrong height it's adjusted by tapping on the little pin in the airflow meter housing under the fuel inlet on the fuel head with a small drift punch.
You should have the instructions and specs which are in the K-jetronic manual and know what you're doing with this tricky adjustment before messing with it though.

If the sensor plate is too high while the pumps are running and control pressure is pushing the plate up the pin needs to be driven down into the housing a little. The fuel inlet line has to be unscrewed and removed to do that.

It the plate is too low then the whole airflow meter housing needs to be removed from the car, then the upper and lower halves get unbolted and seperated, and you have to drive the pin upwards or outwards from inside the housing... fun stuff.
Do it repetitively and the interference fit of the pin in the housing may get too loose to hold it.
Old 07-28-2010, 10:01 AM
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just put my motor back into my car, actually had the green and blue plugs crossed and the fuel pumps wouldn't stay running. Just double check... With the ignition 'on' you should be able to hear the fuel pumps run when depressing the air meter plate, does this work for you?
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Old 07-28-2010, 01:11 PM
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930 wont start

Hi there, firstly i am no mechanic so am just wanting some help to pass onto the mechanic. Might sound strange asking for advice for the mechanic, but i am sick and tired of taking my car to him and the problem still exist.

If i try start the car for the first time it turns over (brand new battery) but doesnt fire up. I can hear the fuel pump working. I can then push start the car and it fires up immediately. I can leave the car to run for 2 min or so, switch it off. Turn the key again and it starts immediately. I can drive the car all day turning it on and off by the key. Leave it over night and the next day same f@&)ing thing. Wont start. Jump it down the hill and it works perfectly all day.

Please can someone give me an idea as to what might be the problem. Cause every hour the mechanic looks for the issue costs me money.

Thanks
Old 06-29-2013, 03:59 AM
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Quote:
Originally Posted by warreng View Post
Hi there, firstly i am no mechanic so am just wanting some help to pass onto the mechanic. Might sound strange asking for advice for the mechanic, but i am sick and tired of taking my car to him and the problem still exist.

If i try start the car for the first time it turns over (brand new battery) but doesnt fire up. I can hear the fuel pump working. I can then push start the car and it fires up immediately. I can leave the car to run for 2 min or so, switch it off. Turn the key again and it starts immediately. I can drive the car all day turning it on and off by the key. Leave it over night and the next day same f@&)ing thing. Wont start. Jump it down the hill and it works perfectly all day.

Please can someone give me an idea as to what might be the problem. Cause every hour the mechanic looks for the issue costs me money.

Thanks
Weird. I'm not a mechanic, but my most times illogical brain thinks there must be a correlation between the high amp draw when cranking the engine and either the pumps not running or ignition not igniting. You say you can hear the pumps running.....I presume that's with the key turned to "on" prior to cranking the engine? Unless you've got stellar hearing, I don't know how you could hear the pumps run while cranking the engine (technically, they shouldn't run until you crank and draw air down across the fuel metering plate to trip a micro switch, but many of these cars have bypassed that safety function and the pumps can be heard to run with just the key turned to the 'on' position).

Go up to the fuse box and pull the single fuse that protects both pumps. Clean it and the fuse holder well. Then, unscrew the wires that link to the fuse holder and clean it as well and retorque. If those connections are poor you could be seeing a large voltage drop when cranking the engine.

Just guessing at this point.
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Old 06-30-2013, 02:55 PM
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930 not starting

Hi Mark,

In this case as you said, that safety feature must have been disconnected cause i can clearly hear what sounds to me as the pump working. I minght even be wrong, it might not be the pump at all.but when the ignition is on the is a low humming noise which remains constant till the engine starts or obviously until the key is switched to the off button.

I will look at the wiring myself then and report back. What does however surprise me is that once it is started, and has run for a bit, it cranks over and starts without a problem, untill i leave it for 8 hours or so.

Anyway will get onto the wire now.

Thanks
Old 07-01-2013, 06:44 AM
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When you turn the key to the on w/o starting the car you should hear a constant high pitched whine. That's your CDI box. If you depress the metering plate while the key is on you should hear the fuel pumps being activated.
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Old 07-01-2013, 08:31 AM
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Quote:
Originally Posted by pkabush View Post
When you turn the key to the on w/o starting the car you should hear a constant high pitched whine. That's your CDI box. If you depress the metering plate while the key is on you should hear the fuel pumps being activated.
There is yet one more 'noise' you'll hear, and that would be the frequency valve that's part of the lambda system. It buzzes, the CDI wines, and the pumps purr.
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Old 07-01-2013, 09:00 AM
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check the cold control pressures

plugs cap and rotor in good condition

residual pressure. check valve and/or fuel accumulator

cold start circuit. CSV, thermo time switch

air leaks.

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Old 07-02-2013, 07:05 AM
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