Another no start problem

[1fastm70]

Well my 80 930 does start but dies soonly after about 2 to three seconds later. So far I have replaced dizzy, wires, plugs, all vaccum hoses, wur, and metering plate switch. I don't what else could be causing this. Please help. Oh and new fuel relays.

[jsveb]

Originally Posted by 1fastm70

Well my 80 930 does start but dies soonly after about 2 to three seconds later. So far I have replaced dizzy, wires, plugs, all vaccum hoses, wur, and metering plate switch. I don't what else could be causing this. Please help. Oh and new fuel relays.

HI

I suggest you folloe some of the advice I have been given, and take what is relevant for you. Sounds like maybe some of of will work for you.

Good luck

Jesper

[mark houghton]

Had that happen once to me. Replaced both fuel pump relays with new; still did it. Got some electrical contact cleaner in a spray can and hosed down inside the female relay plugs to clean then out. No problems since.
Of course, there are a whole host of other things than can cause this.

[IMR-Merlin]

Does the fuel pump get a trigger from the ignition? Sounds to me that the fuel pumps is running on the start circuit, but not on the ignition circuit.

But I am not completely familiar with these cars yet.

[1fastm70]

well fuel pumps work and so does ignition. if i push down the metering plate, i can mantain the engine running. I really have no idea what would cause this.

[OSI930]

I see that you replaced the metering plate switch. When you are pushing down on the metering plate to keep the car running, is the metering plate switch connected?

[1fastm70]

yes it is connected. when unplugged and the ignition on the pumps turn on but car doesn't keep running.

[mark houghton]

Ckeck, clean, and/or replace both fuel pump relays up front, as well as the single fuel pump fuse connections (clean, re-torque the wire nuts).

Check the connection to the overboost switch. If in doubt, unplug it and ground it to take the sensor out of the equation.

Check/clean the infamous "yellow relay" in the rear fuse panel (for 1980, it may be a round black or red).

Finally, if you've got a Lambda control circuit, then under the drivers seat would be the circuit board and relays, etc. associated with it. One of those relays is the "overspeed" relay and a bad connection there can shut down your pumps.

[1fastm70]

Checked and did everything mentioned here but the car is still the same. I think it is something with the fuel distributor but expensive to replace and then to end up not being the culprit. Anyone know what the primary system pressure is supposed to be? Thanks really appreciate the help guys.

[mark houghton]

Originally Posted by 1fastm70

well fuel pumps work and so does ignition. if i push down the metering plate, i can mantain the engine running. I really have no idea what would cause this.

That is an important clue. You also stated that the pumps will run with the ignition in the ON position and the metering plate switch unplugged...as it should. But in order to keep the car running you have to manually depress the metering arm (thus adding fuel). Does the arm move freely (stupid question, but had to be asked).

Something fuel delivery related, probably. Sounds like it's time for a CIS pressure testing gauge (join the club, as Jesper just did!). Can't diagnose without information. I feel like a broken record....encouraging folks to buy the guage setup, but it's such an important part of tuning and/or troubleshooting these cars.

To answer your question, "System" fuel pressure should be in the neighborhood of 6.2 - 6.5 bar (in that area, + as my memory says without going to look it up). Also check that your cold control pressure isn't too high, not allowing a rich enough mixture to keep her running when cold. Hopefully your worse case scenario is a faulty WUR...but you won't know until you test it.

[jsveb]

Originally Posted by mark houghton

That is an important clue. You also stated that the pumps will run with the ignition in the ON position and the metering plate switch unplugged...as it should. But in order to keep the car running you have to manually depress the metering arm (thus adding fuel). Does the arm move freely (stupid question, but had to be asked).

Something fuel delivery related, probably. Sounds like it's time for a CIS pressure testing gauge (join the club, as Jesper just did!). Can't diagnose without information. I feel like a broken record....encouraging folks to buy the guage setup, but it's such an important part of tuning and/or troubleshooting these cars.

To answer your question, "System" fuel pressure should be in the neighborhood of 6.2 - 6.5 bar (in that area, + as my memory says without going to look it up). Also check that your cold control pressure isn't too high, not allowing a rich enough mixture to keep her running when cold. Hopefully your worse case scenario is a faulty WUR...but you won't know until you test it.

Hi

Rookie here, so beware. The best advice I can give you, is do what he says -Listen

If I was to take a wild guess, your control pressure is too high.

Rookie (me) I know, but you'll find out once you get the CIS tester.

I got a suggestion. (Feel free to tell him not to, if you think it is just too stupid).

Turn on the ignition and unplug the green safety wire to make the pumps run. If you have the air filter on push down gently on the CO adjuster (The one that affects the metering plate when adjusting). If you don't just push down ever so gently and very brief on the metering plate. If you have pressure in the system, don't unplug the green plug. Just push a little on the plate

Now go and crank the car. Once it "stumbles" to life, be ready with the throttle, easy know or you'll flood it. If your fault is the same as mine. This would make your car run.

9Dreizig did this when he had some problems with his WUR. That's where I got the idea
Digital WUR

Hope it helps you

Jesper

[spuggy]

Originally Posted by mark houghton

That is an important clue. You also stated that the pumps will run with the ignition in the ON position and the metering plate switch unplugged...as it should. But in order to keep the car running you have to manually depress the metering arm (thus adding fuel). Does the arm move freely (stupid question, but had to be asked).

+1 What Mark said.

It sounds to me as though the metering plate switch maybe isn't turning on the fuel pumps when the motor is running.

[mark houghton]

Originally Posted by spuggy

+1 What Mark said.

It sounds to me as though the metering plate switch maybe isn't turning on the fuel pumps when the motor is running.

If the switch were faulty, then leaving the metering plate switch unplugged at all times (thus the pumps would run independent of the switch, anytime the ignition was turn to ON) would take the switch out of the equation. But the arm must deflect as air is drawn across the plate in order for fuel to flow to the injectors.

[1fastm70]

I thought it was the wur and I ordered a rebuilt one. So not really sure if this is still not right. I got a tester but never knew the numbers I was supposed to get, so I'll hook it up and get back with you guys. Thanks.

[1fastm70]

Sorry guys got kind of busy with school but I got around to checking this.
I tested system pressure and got 5.9 bar. It's supposed to be 6.2-6.5. Lower than what it's supposed to be but fairly close. Could this be a problem?
I then tested the Cold pressure and got 2.3 bar compared to the 1.8-2.2 bar it's suppose to be according to the previous thread(1978 no start).

So what do you guys think about these numbers?

[spuggy]

Originally Posted by 1fastm70

I tested system pressure and got 5.9 bar. It's supposed to be 6.2-6.5. Lower than what it's supposed to be but fairly close. Could this be a problem?

It's out of spec. .

I've run a single 044 pump with system pressure at 80 PSI (5.44 bar) and dyno'd considerably in excess of 300 RWHP - I don't think that's your starting problem, although this may indicate adjustment required or an issue. It should start even with a dead pump in a dual pump setup.

I then tested the Cold pressure and got 2.3 bar compared to the 1.8-2.2 bar it's suppose to be according to the previous thread(1978 no start).

So what do you guys think about these numbers?

Slightly high (lean). Shouldn't make it die once its running.

[spuggy]

Originally Posted by mark houghton

If the switch were faulty, then leaving the metering plate switch unplugged at all times (thus the pumps would run independent of the switch, anytime the ignition was turn to ON) would take the switch out of the equation.

Exactly. Remember the issues Alan L had with a metering plate that freaked out bouncing around at idle turning the pumps on and off?

I'd be inclined to disconnect the metering plate switch for testing, see if the car ran without it in circuit and go from there.

But the arm must deflect as air is drawn across the plate in order for fuel to flow to the injectors.

Agreed. What I'm thinking is, if the metering plate position was incorrectly adjusted relative to the switch (or fuel pressure fluctuation was making it bounce around the switch activation point) at idle, it might not be deflecting enough to keep the pumps running.. Then it'd die a few seconds later as it consumed the fuel/pressure already in the system.

Should be easy to check.

[jsveb]

Hi

My control pressures came out higher than that (around 2.7-2.9) I can now start the car anyways. I would guess (as they say in the above posts, that CP is not your (only) starting problem. My system pressure came out at 5.9bar as well.

Jesper

[1fastm70]

So you guys don't think it is the wur?

I think there is a pin in which you have to hit with a punch or something of that sort. Is this the adjustment that you mean? How do. I know if it's right or wrong? -the metering plate position.

[1fastm70]

So I managed to get the car up to normal operating temp and thought maybe the car wouldn't die as mentioned by spuggy earlier but it still dies if I let go of the plate.

Then while warming up there was lots of smoke(oil) that came out of the exhaust. Thinking it could be the turbo seals or something that re leaking, but don't think that would be my problem.
I accelerated the engine once warm and there was no signs of boost on the gauge.